From majordomo-owner@berlioz.nsc.com Tue Apr 1 14:15:06 1997 Date: Tue, 1 Apr 97 14:15:05 PST To: jmoss From: majordomo@berlioz.nsc.com Subject: Majordomo file: list 'laser' file 'laser.9703' Reply-To: majordomo@berlioz.nsc.com Content-Length: 342626 -- >From owner-laser Sat Mar 1 14:47:32 1997 Return-Path: Received: by berlioz.nsc.com (4.1/SMI-4.1) id AA00948; Sat, 1 Mar 97 14:47:32 PST Date: Sat, 1 Mar 97 14:47:29 PST From: jmoss (Jim Moss) Message-Id: <9703012247.AA00941@berlioz.nsc.com> To: laser Subject: info on H957-08? Sender: owner-laser@berlioz.nsc.com Precedence: bulk I just found a source of Hamamatsu H957-08 tubes. Anyone have specs on these? I'll try Hamamatsu later in the week if no response. Jim WB9AJZ/6 >From owner-laser Sun Mar 2 12:58:35 1997 Return-Path: Received: by berlioz.nsc.com (4.1/SMI-4.1) id AA22698; Sun, 2 Mar 97 12:58:35 PST From: sjnoll@ix.netcom.com Date: Sun, 2 Mar 1997 14:53:19 -0600 (CST) Message-Id: <199703022053.OAA09933@dfw-ix11.ix.netcom.com> Mime-Version: 1.0 Content-Type: text/plain Content-Transfer-Encoding: 7bit Subject: Re: info on H957-08? To: laser@berlioz.nsc.com In-Reply-To: <9703012247.AA00941@berlioz.nsc.com> X-Mailer: SPRY Mail Version: 04.10.06.22 Sender: owner-laser@berlioz.nsc.com Precedence: bulk On Sat, 1 Mar 97, jmoss@berlioz.nsc.com (Jim Moss) wrote: >I just found a source of Hamamatsu H957-08 tubes. >Anyone have specs on these? >I'll try Hamamatsu later in the week if no response. >Jim >WB9AJZ/6 I have a 1979 Hamamatsu catalog that only says it is obsolete and is a "Hybrid PMT". No further info was given. Steve J. Noll | Ventura CA | WA6EJO | sjnoll@ix.netcom.com | http://www.netcom.com/~sjnoll/usedequip.html | http://www.netcom.com/~sjnoll/peltier.html >From owner-laser Mon Mar 3 09:22:23 1997 Return-Path: Received: by berlioz.nsc.com (4.1/SMI-4.1) id AA18300; Mon, 3 Mar 97 09:22:23 PST Date: Mon, 3 Mar 97 09:22:20 PST From: jmoss (Jim Moss) Message-Id: <9703031722.AA18288@berlioz.nsc.com> To: laser Subject: Re: info on H957-08? and range equation Sender: owner-laser@berlioz.nsc.com Precedence: bulk Steve (WA6EJO), thanks for looking. Appears this is a shielded R928, with powersupply and voltage divider internal. 15 v required. Do you have specs on R928? Glad to hear you are still reading the LASER reflector. Really appreciate your past posts. Was re-reading your March 96 stuff on the range equation. (available in the March 96 archive) Now after a year of fooling around, I am much more able to understand the practical nature of it. The attenuation due to scattering that you mentioned before does appear to be based on a 50/50 weighting of "continental air and maritime air". This is why the scattering is so high, especially at sea level. This is approximately the same aerosol scattering as about 57% Relative Humidity. So the assumption of "clear air day" may work, but probably we need to look more closely at adjusting RH (humidity) assumptions, and then on clarity? Jim WB9AJZ/6 >From owner-laser Mon Mar 3 18:14:42 1997 Return-Path: Received: by berlioz.nsc.com (4.1/SMI-4.1) id AA06716; Mon, 3 Mar 97 18:14:42 PST Date: Mon, 3 Mar 97 18:12:47 PST From: jmoss (Jim Moss) Message-Id: <9703040212.AA06566@berlioz.nsc.com> To: laser, vhf@w6yx.stanford.edu Subject: LASER WEB PAGE! Sender: owner-laser@berlioz.nsc.com Precedence: bulk LIGHT UP YOUR LIFE! We had so many subscribers to the laser reflector that I went and got a free account at www.qsl.net I quickly built a web page with all the info from the LASER mail reflector archives (except for the month in process - Mar), and various files that I have collected, and bunches of laser related links (sorted by subject). try: http://www.qsl.net/wb9ajz/laser.htm If you have any suggestions, please let me know via mailto:wb9ajz@qsl.net If anyone wants to volunteer to edit the archives into subject... I'll be happy to post your handiwork. 73, Here's looking for you! Jim WB9AJZ/6 >From owner-laser Mon Mar 3 18:17:38 1997 Return-Path: Received: by berlioz.nsc.com (4.1/SMI-4.1) id AA06803; Mon, 3 Mar 97 18:17:38 PST Date: Mon, 3 Mar 97 18:17:36 PST From: jmoss (Jim Moss) Message-Id: <9703040217.AA06797@berlioz.nsc.com> To: laser, vhf@w6yx.stanford.edu Subject: OOPS: LASER WEB PAGE! Sender: owner-laser@berlioz.nsc.com Precedence: bulk see corrected link! ----- Begin Included Message ----- >From jmoss Mon Mar 3 18:12:45 1997 To: laser, vhf@w6yx.stanford.edu Subject: LASER WEB PAGE! Content-Length: 612 LIGHT UP YOUR LIFE! We had so many subscribers to the laser reflector that I went and got a free account at www.qsl.net I quickly built a web page with all the info from the LASER mail reflector archives (except for the month in process - Mar), and various files that I have collected, and bunches of laser related links (sorted by subject). try: http://www.qsl.net/wb9ajz/laser/laser.htm If you have any suggestions, please let me know via mailto:wb9ajz@qsl.net If anyone wants to volunteer to edit the archives into subject... I'll be happy to post your handiwork. 73, Here's looking for you! Jim WB9AJZ/6 ----- End Included Message ----- >From owner-laser Tue Mar 4 02:43:31 1997 Return-Path: Received: by berlioz.nsc.com (4.1/SMI-4.1) id AA20224; Tue, 4 Mar 97 02:43:31 PST Date: Tue, 4 Mar 97 10:35:53 UT From: "John Yurek" Message-Id: To: "Laser Messages" Subject: Dumont 6292 PMT Sender: owner-laser@berlioz.nsc.com Precedence: bulk Hey it's sure nice to see this group come to life after many months of nothing! I posted this a LONG time ago and never got any response but with all the new people out there perhaps someone can fill in a bit of info for me. Many years ago I was handed a Dumont 6292 PMT (Photo Multiplier Tube). It came mounted with a bunch of 330 k resistors already mounted on the socket. On the back of the assembly is a High Voltage jack and a signal jack. It appears to be homebrew although some commercial designs of that era looked about the same! Anyone have an idea as to the spectral response and frequency response of this tube? How much high voltage does it need? How much light can it take? I know that exposure to bright light can temporarily degrade the sensitivity of a PMT but I was more interested in preventing any permanent damage! About the only PMT I've ever played around with was a 931-A many years ago. Just by looking at this tube though one can tell that it's orders of magnitude better than something like that! Thanks John K3PGP@msn.com >From owner-laser Tue Mar 4 06:37:09 1997 Return-Path: Received: by berlioz.nsc.com (4.1/SMI-4.1) id AA24491; Tue, 4 Mar 97 06:37:09 PST From: sjnoll@ix.netcom.com Date: Tue, 4 Mar 1997 08:32:53 -0600 (CST) Message-Id: <199703041432.IAA00957@dfw-ix9.ix.netcom.com> Mime-Version: 1.0 Content-Type: text/plain Content-Transfer-Encoding: 7bit Subject: R928 PMT specs. To: laser@berlioz.nsc.com X-Mailer: SPRY Mail Version: 04.10.06.22 Sender: owner-laser@berlioz.nsc.com Precedence: bulk R928 PMT 1 1/8" dia side-on type. Extended red high sensitivity multialkali photocathode. 185nm - 930nm, 400 nm peak. UV glass window. 9 stages. 1250V max, anode-cathode. 250V max, anode-last dynode. 0.1 mA max average anode current. 140 uA/lm min luminous sensitivity. 200 uA/lm typical luminous sensitivity. 6.8 x 10^5 A/W anode radiant sensitivity. 2000 A/lm typical anode luminous sensitivity. 1 x 10^7 typcial current amplification. 2.2 nS typical rise time. Steve J. Noll | Ventura CA | WA6EJO | sjnoll@ix.netcom.com | http://www.netcom.com/~sjnoll/usedequip.html | http://www.netcom.com/~sjnoll/peltier.html >From owner-laser Tue Mar 4 06:44:37 1997 Return-Path: Received: by berlioz.nsc.com (4.1/SMI-4.1) id AA24686; Tue, 4 Mar 97 06:44:37 PST From: sjnoll@ix.netcom.com Date: Tue, 4 Mar 1997 08:43:23 -0600 (CST) Message-Id: <199703041443.IAA22672@dfw-ix5.ix.netcom.com> Mime-Version: 1.0 Content-Type: text/plain Content-Transfer-Encoding: 7bit Subject: Dumont 6292 PMT To: laser@berlioz.nsc.com X-Mailer: SPRY Mail Version: 04.10.06.22 Sender: owner-laser@berlioz.nsc.com Precedence: bulk Hamamatsu says their 7696 is a substitute for this. 7696 2" dia head-on type with plastic base. S-11 response, general purpose. 300nm-650nm, 440 nm peak. 10 dynodes. 1500V max anode-cathode. 250V max anode-last dynode. 0.1 mA max average anode current. 40 uA/lm min luminous sensitivity. 80 uA/lm typical luminous sensitivity. 64 mA/W typical radiant cathode sensitivity. 4 x 10^4 A/W typical radiant anode sensitivity. 50 A/lm typical anode luminous sensitivity. 6.3 x 10^5 typical current amplification. 14 nS rise time. Steve J. Noll | Ventura CA | WA6EJO | sjnoll@ix.netcom.com | http://www.netcom.com/~sjnoll/usedequip.html | http://www.netcom.com/~sjnoll/peltier.html >From owner-laser Tue Mar 4 20:51:02 1997 Return-Path: Received: by berlioz.nsc.com (4.1/SMI-4.1) id AA21257; Tue, 4 Mar 97 20:51:02 PST From: Lbo@kktv.com Message-Id: <199703050446.UAA04515@natsemi-bh.nsc.com> To: laser@berlioz.nsc.com Date: 4 Mar 1997 22:07:10 -0700 Subject: HeNe Laser Wanted Sender: owner-laser@berlioz.nsc.com Precedence: bulk i need a HeNe CW laser 5-30mW. Paul, w0rw@kktv.com >From owner-laser Wed Mar 5 04:54:56 1997 Return-Path: Received: by berlioz.nsc.com (4.1/SMI-4.1) id AA02007; Wed, 5 Mar 97 04:54:56 PST Message-Id: <199703051252.HAA01425@host-04.colby.edu> X-Sender: aballen@colby.edu X-Mailer: Windows Eudora Light Version 1.5.2 Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Date: Wed, 05 Mar 1997 07:52:51 -0500 To: laser@berlioz.nsc.com From: "Art Allen, KY1K" Subject: Re: HeNe Laser Wanted Sender: owner-laser@berlioz.nsc.com Precedence: bulk >i need a HeNe CW laser 5-30mW. >Paul, w0rw@kktv.com Years ago, N7BYL, Earl from Amherst, MA had a 20 mw HE-NE with PS. At the time, Earl wanted 300 dollars for it, and I wasn't going to pay that much. No one else would either, the tube fired at the time, but it was an old tube then, and is probably no younger now. I do not know if he still has it, but if so, my guess is that he might be ready to sell at a more reasonable rate. It might be worth looking him up in the phone book and giving him a call. If anyone contacts him, and DOESN'T purchase, I'd appreciate it if you could post the results of the call here. Art, KY1K. >From owner-laser Wed Mar 5 07:40:53 1997 Return-Path: Received: by berlioz.nsc.com (4.1/SMI-4.1) id AA05447; Wed, 5 Mar 97 07:40:53 PST Message-Id: <199703051538.KAA15107@host-04.colby.edu> X-Sender: aballen@colby.edu X-Mailer: Windows Eudora Light Version 1.5.2 Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Date: Wed, 05 Mar 1997 10:38:24 -0500 To: laser@berlioz.nsc.com From: "Art Allen, KY1K" Subject: Re: info on H957-08? Sender: owner-laser@berlioz.nsc.com Precedence: bulk I have a 1990 catalog, called 'Electron Tube Products'. It has spec's for the H957-08, and doesn't mention it as being a 'obsolete'. I'd treat these as usable, but don't count on support from Hamamatsu. As far as I can tell, we should be able to get 10e-14 sensitivity from these, and they do run on batteries. Sounds like a good deal to me. GL..Art... At 02:53 PM 03/02/1997 -0600, you wrote: >On Sat, 1 Mar 97, jmoss@berlioz.nsc.com (Jim Moss) wrote: >>I just found a source of Hamamatsu H957-08 tubes. >>Anyone have specs on these? >>I'll try Hamamatsu later in the week if no response. >>Jim >>WB9AJZ/6 > >I have a 1979 Hamamatsu catalog that only says it is obsolete and is a >"Hybrid PMT". No further info was given. > >Steve J. Noll | Ventura CA | WA6EJO | sjnoll@ix.netcom.com > | http://www.netcom.com/~sjnoll/usedequip.html > | http://www.netcom.com/~sjnoll/peltier.html > > >From owner-laser Wed Mar 5 09:09:31 1997 Return-Path: Received: by berlioz.nsc.com (4.1/SMI-4.1) id AA07793; Wed, 5 Mar 97 09:09:31 PST Message-Id: <199703051705.MAA23898@host-04.colby.edu> X-Sender: aballen@colby.edu X-Mailer: Windows Eudora Light Version 1.5.2 Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Date: Wed, 05 Mar 1997 12:05:20 -0500 To: "John Yurek" From: "Art Allen, KY1K" Subject: Re: Dumont 6292 PMT Cc: laser@berlioz.nsc.com Sender: owner-laser@berlioz.nsc.com Precedence: bulk >How much high voltage does it need? How much light can it take? I >know that exposure to bright light can temporarily degrade the sensitivity of >a PMT but I was more interested in preventing any permanent damage! Hi John, Most PM tubes take 300 to 1300 volts-some use as high as 1500v. The current drawn is very very low, so a properly designed voltage dc-dc makes them usable where there is no comm'l power. With resistors in the divider string, the majority of the current needed is WASTED by the divider string itself-the tube actually consumes very little power itself. Even SHORT exposure to daytime light levels will degrade the performance of a PMT. It may take the PMT 2 or 3 days to recover from such exposures. The tube will draw high current even in the dark. This 'current' is noise and will mask lower levels of light input. This temporary condition occurrs whether the tube is powered up, or not. By this, I mean that you can expose it to daylight WITHOUT power applied, and the tube will take days to recover before it becomes usable again for weak signals. ------------------- If you expose the PMT to bright daylight or near direct sun, or close range with a flashlight, you can do permanent damage to the photocathode. This is because the photocathode can be warped and physically distorted by high levels of light. This can also happen even if the tube is not powered up. It happens because the photocathode is so fragile, and because light has MASS. -------------------- Keep those tubes in the dark and store them with covers over them, even when they aren't in use.. Used tubes found at flea markets should sell for very low $$, because the owner can't guarantee that the tube has never been abused and you can't test the tube or tell if it has been damaged by looking at it. Incidently, the Hamatsu catalogs contain a wealth of technical info. If you are interested in PMT's, you should get the catalogs for PMT's. They DO NOT have a WWW site, I just looked several weeks ago. GL, Art, KY1K. >From owner-laser Wed Mar 5 09:05:12 1997 Return-Path: Received: by berlioz.nsc.com (4.1/SMI-4.1) id AB07639; Wed, 5 Mar 97 09:05:12 PST Date: Wed, 5 Mar 97 09:05:07 PST From: jmoss (Jim Moss) Message-Id: <9703051705.AA07614@berlioz.nsc.com> To: laser Subject: RE:HeNe Laser Wanted Sender: owner-laser@berlioz.nsc.com Precedence: bulk Paul, and all, Halted Specialties (HSC) here in Santa Clara, California has just got a bunch of 5mW tubes 4-6mW priced from $79-89 each (w/o PS). They are out of power supplies. Tubes are all MG brand. HSC 408-732-1573 M-F 8A-7P S 9A-5P PST Jim WB9AJZ/6 ----- Begin Included Message ----- >From owner-laser Tue Mar 4 23:59:28 1997 From: Lbo@kktv.com To: laser@berlioz.nsc.com Date: 4 Mar 1997 22:07:10 -0700 Subject: HeNe Laser Wanted Sender: owner-laser@berlioz.nsc.com Content-Length: 55 i need a HeNe CW laser 5-30mW. Paul, w0rw@kktv.com ----- End Included Message ----- >From owner-laser Wed Mar 5 09:40:57 1997 Return-Path: Received: by berlioz.nsc.com (4.1/SMI-4.1) id AA08818; Wed, 5 Mar 97 09:40:57 PST Date: Wed, 5 Mar 97 09:40:53 PST From: jmoss (Jim Moss) Message-Id: <9703051740.AA08793@berlioz.nsc.com> To: laser Subject: RX methods Sender: owner-laser@berlioz.nsc.com Precedence: bulk Recommend you read laser602.txt in the achives to see some of the things that we've tried before with RX methods. You can see this file only on the website (it is a collection of pre-reflector mails sent by the "original" reflector members). Also for those playing with solar cells... take a look at http://www.qsl.net/wb9ajz/laser/data/solarcel.xls This is an Excel file that shows frequency response for a small 4 bay, 1/4"x1/4" each bay, cell (like from a calculator supply). Very poor > 30 Hz. I'd rank rx capabilities for worst to best: 7) solar cell 6) phototransistor (avail at Radio Shack also) 5) Photo PIN diodes (find surplus) 4) BurrBrown PIN + Op Amp integrated 3) APD's (Avalanche PIN Diodes) Need HV. 2) PMT's (Photo Multiplier Tubes ) Need HV. 1) Eyes Jim WB9AJZ/6 >From owner-laser Wed Mar 5 09:59:47 1997 Return-Path: Received: by berlioz.nsc.com (4.1/SMI-4.1) id AA09484; Wed, 5 Mar 97 09:59:47 PST Date: Wed, 5 Mar 97 09:59:44 PST From: jmoss (Jim Moss) Message-Id: <9703051759.AA09470@berlioz.nsc.com> To: laser Subject: WB9AJZ station status Sender: owner-laser@berlioz.nsc.com Precedence: bulk An update on my current status and projects: Station now: TX measured: 3mW 670nM laser pointer with 1mR divergence, modulated with 800 Hz for MCW using a 555 and a key on the enable line (see cheapo.txt Tx section). RX: Surplus photodiode (about .3" per side) specs unknown, with amplification thru Bi-FET low noise Op Amps. (about 1 million x) Then thru a LM386 audio amp. 8" magnifying mirror for light collection. Aiming: RX is on tripod and aimed manually for peak signal (bore site down the line of the horizontal support holding mirror and rx. TX is on a seperate tripod, uses surplus leadscrew systems powered by stepper motors, and interfaced to parallel port of portable PC. TX is aimed best as can with boresiting, then tell PC to "raster" scans horiz, and steps vert, until target yells "THERE!" via radio. Then step motors manually. Specs on motion control is about 0.1 mR per step. <10 steps per beam width> More details on how all this works some other time. Best DX: to AJ6T, Walt... 20.1 miles with strong signals but QSB. Research: 1) 12" reflector obtained, will try with solid state RX's 2) PMT bought, will build up a RX and try it. 3) Digital Modulation: a) have tried using RS232 port to modulate laser directly, works at 115kB at over 50 ft with no lenses and VERY simple rx b) Ran a 1MHz sq wave and 4MHz sq waves into laser pointer, showed basic operation at <3 ft> didn't try for more. c) attended class on digital voice encoding, possible application d) confused on what direction to go! Compliance with IRDA would allow PC's with IR to be RX's and could allow "repeaters" from IR to laser and back. Voice- seems everyone likes it. CW many don't like it but it's easy and goes farther. 4) extend distance to 54 miles, soon! Mt Diablo to Loma Prieta is the plan. Jim WB9AJZ/6 CM87xi Sunnyvale, CA >From owner-laser Wed Mar 5 18:47:46 1997 Return-Path: Received: by berlioz.nsc.com (4.1/SMI-4.1) id AA27466; Wed, 5 Mar 97 18:47:46 PST Date: Wed, 5 Mar 1997 21:44:27 -0500 (EST) Message-Id: <2.2.16.19970305220956.283f0b2c@mail.snet.net> X-Sender: paulc@mail.snet.net X-Mailer: Windows Eudora Pro Version 2.2 (16) Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" To: laser@berlioz.nsc.com From: "Paul A. Cianciolo" Subject: HP snap-in fiber optic link for trade Sender: owner-laser@berlioz.nsc.com Precedence: bulk Hello All, Any one want to trade for a HP snap-in fiber optic link? Complete with TX RX approx 25' of fiber optic cable with connectors on each end and spares, polishing tool etc. Please respond to PaulC@snet.net 73's PaulC KB1RP >From owner-laser Thu Mar 6 08:35:23 1997 Return-Path: Received: by berlioz.nsc.com (4.1/SMI-4.1) id AA16956; Thu, 6 Mar 97 08:35:23 PST Message-Id: <199703061623.LAA29098@host-04.colby.edu> X-Sender: aballen@colby.edu X-Mailer: Windows Eudora Light Version 1.5.2 Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Date: Thu, 06 Mar 1997 11:23:44 -0500 To: laser@berlioz.nsc.com From: "Art Allen, KY1K" Subject: NU1N? Sender: owner-laser@berlioz.nsc.com Precedence: bulk Hey guys, NU1N worte a fairly decent article in QST some years ago regarding laser comm. We should get him on the list, if he has internet capability and if he still does lasers. Last known address was in Canada, but before that, he lived in the Boston Area. Anyone have any contact with him recently? Also, the 7 landers in AZ who hold the North American record at 170 miles...anyone have any info about them? Art, KY1K. >From owner-laser Thu Mar 6 16:01:17 1997 Return-Path: Received: by berlioz.nsc.com (4.1/SMI-4.1) id AA02612; Thu, 6 Mar 97 16:01:17 PST Date: Thu, 6 Mar 97 23:30:20 UT From: "John Yurek" Message-Id: To: "Laser Messages" Subject: FM Subcarriers on Lasers ! Sender: owner-laser@berlioz.nsc.com Precedence: bulk There seems to be quite a bit of interest in putting voice or data on a laser beam for those of us that aren't into using CW all the time. With the increase in readers to this newsgroup I thought this might be the time to offer some details of experiments that I've done in the past with FM subcarriers on laser beams. As pointed out by several people here it is possible to modulate a laser diode (like the ones in the typical laser pen) at quite high frequencies. With this in mind I built up a square wave oscillator that could be frequency modulated with an audio voltage. You can use most any IC for the oscillator. Just make sure you have a way to swing it a couple of Khz linearly with a couple of volts of audio! The frequency of the square wave oscillator should be at least twice the desired modulating frequency to avoid developing any beat frequencies. The same rules seem to apply here as when dealing with A/D converters. (The sampling rate should be at least twice the rate of the highest input frequency.) In my case I am using carrier frequencies in the 20 to 100 Khz region. For receiving the FM signals you simply take what used to be the audio output from your laser receiver and run it into either a VLF converter or an FM SCA receiver. These typically run at 67 Khz and use a PLL. It's nothing more than a simple NBFM receiver. I have had the best results using a VLF converter ahead of a communications receiver that can demodulate NBFM. If you are using a commercial VLF converter and it has an RF stage be careful not to overload it. You may need to attenuate the output of the laser detector amp! My VLF converter consists of a double balanced mixer (NO RF stage!) fed with a RF oscillator. I like to use either 3.5, 7, or 144 Mhz for the LO so I don't need a general coverage receiver and can use any ham band only unit. The receiver would then be tuned to the sum frequency. For a 67 Khz subcarrier it would be either 3567 Khz or 7067 Khz or 144.067 Mhz. This can also be made to work with a two meter IF! In this case you would use 144 Mhz (I suggest this to avoid leak through interference from strong local FM repeaters!) for the local oscillator. (It's OK to use something like a 48 Mhz oscillator/tripler.) You might need to do a bit of shielding and balancing to keep the local oscillator leak through to reasonable levels but this can be made to work. This way all you need to drag with you is the two meter hand held! In this case you would tune to 144.065 if using a 65 Khz subcarrier system or tune to 144.065 and offset the 144 Mhz to make up the 2 Khz error if using 67 Khz. This system will produce broadcast quality audio if you use wide band FM. If you are using NBFM filters in the receiver of course you will limit the frequency response to the typical voice communications quality like you would hear on two meters. ----- Note: It is possible to put more than one subcarrier on a laser beam. I have done this many times. If you have your laser diode set up so it can be modulated at frequencies in the Mhz region you can even set up an FM video system. If you are going to attempt this you will need to investigate any large value capacitors in the power supply regulator circuitry feeding the laser diode. These tend to roll off the response in such a way that the laser will simply not follow the high frequency transitions. If your laser pointer has something like a 100 uf capacitor across the battery terminals you won't even get 20 Khz through it! I pulled the FM modulator and demodulator boards out of an old VCR which in my case were running around 2.5 to 4.5 Mhz. The modulator was used to feed the laser diode and the demod board was used on the receive end. Worked like a champ for video! If you want to run color on a low frequency subcarrier like this you will also have to steal the color processing boards as well. This technique is know as 'color under' since the color is heterodyned down in frequency so it can be put on the low frequency carrier. If you build your own mod and demod you can run the subcarrier up around 8 to 10 Mhz and make things a LOT simpler for color video work. The sound is then superimposed on the FM video carrier with another FM oscillator running at 4.5 Mhz allowing simultaneous video and audio! More subcarriers can be added to carry other signals at the same time. ----- A word on receivers and detecting high frequency subcarriers. You need to swamp out the inherent capacitance of the detector otherwise the high frequency response will be terrible! This is why silicon solar cells have such poor frequency response. It's all that shunt capacitance. If you load the cell with a low value resistor the high frequency response will improve but then of course you need more amplification to make up for the lost voltage! Using the typical photo transistor or photodiode receiver you also want to use a lower value pull up resistor. I've seen people using values in the megaohm region. This is fine for 800 Hz CW but simply unusable for subcarrier work. The value of this resistor needs to be made much smaller. This also greatly improves reception during daylight hours. I seem to have good success with most anything between 1k and 10 k ohms. -------------------------------------- And now the BIG secret!!! -------------------------------------- OPTICAL BAISING! I mount a RED LED in such a fashion that it can see into the detector. If you are using a photodiode with a clear case you can mount the LED behind the detector. If you are using a metal cased detector you will have to mount the LED off to the side and in front of the detector. The LED goes through a series 1 K resistor and then a small value pot to the B+ line (12 volts in my case). In total darkness you adjust the LED intensity until you measure 6 volts (1/2 B+ value) across the detector. MOST detectors biased like this show quite an improvement in sensitivity but ALL show an enormous improvement in high frequency response as opposed to using a high value pull up resistor. I also tried biasing the third unused lead of a phototransistor and achieved the same effect, that is 1/2 B+ across the detector. However, when I did this the noise floor came up a LOT more than when using the optical biasing. I'm not sure exactly what is going on here but there are definite advantages to using optical biasing. Someone even suggested that the detector may be running as some kind of crude heterodyne system since the RED led used for biasing and the transmitter weren't that far apart in frequency. With this in mind I tried a green and then a yellow LED. Although I could bias the detector to 1/2 B+ with these LEDs the sensitivity was a LOT worse. White light produced more noise than any of the LEDs. So maybe there is more going on here than at first thought! When running this system during daytime you may need to turn the RED bias LED current down a bit or even off. It depends on the detector, the pull up resistor, ambient light, and whether or not you have any optical filtering in front of the detector. You could even design a simple feedback circuit to automatically adjust the bias LED. However, it's just not that critical. Once the detector starts conducting there isn't much difference until the detector saturates so there is a VERY broad linear operating region to play with. Remember we are detecting an FM subcarrier so linearity isn't near as important as with an AM system! Aiming a detector like this up into a cloud covered sky has on several occasions produced loud clicking sounds which I assume was infrared radiation from lighting discharges between clouds that I could not see with my naked eye. These could also be detected much weaker with the detector looking at the ground. (Ground bounce???) The first time this happened I thought I was picking up some kind of electrical interference or something was loose inside the detector assembly. However, putting my hand in front of the detector greatly attenuated (but did NOT eliminate) the interference so I assume that I was indeed detecting some kind of optical phenomena! Only placing a black piece of paper directly over the detector was I successful in totally eliminating this effect, so whatever I was detecting was extremely strong! If you happen to have a PMT (Photo Multiplier Tube) running your all set because these tubes have demodulated response up into the MHz region and will work with any of these subcarrier systems! To those of you that still enjoy playing with gas filled tubes and high voltage supplies these subcarrier techniques can also be applied to He-Ne systems. All you need to do is build up a switching high voltage power supply running at 20 to 100 Khz. The high voltage AC is simply applied to the He-Ne tube through the typical 68k to 100k ballast resistor. The oscillator in the switching power supplied is then FM modulated. You end up with a very high quality FM voice system! I have seen some commercial DC switching supplies where all I had to do was remove the rectifier diode and filter capacitors and add an audio input jack so I could FM the switching oscillator. There seems to be some disagreement as to the effects of AC voltage on He-Ne tubes. Some manufacturers say it's OK and will NOT shorten the life of the tube. Others say it will actually make the tube last longer since impurities in the tube don't collect all on one electrode. Other's say they don't know. I can understand this since if you don't filter the power supply whatever frequency it is running at will modulating the laser tube and most people want a CW carrier, so most He-Ne laser systems use well filtered power supplies! In this case however, this modulation is exactly what we want! I spent many happy hours making the above systems work. Unfortunately there weren't any reference books around where I could look stuff up. So I had to put in the hours to make it work. I now share this knowledge with you. All that I ask in return is that if you make use of any of these techniques that you give credit where credit is due. I hope you enjoyed reading the above and my apologies for taking up the large burst of Internet bandwidth! John K3PGP@msn.com >From owner-laser Thu Mar 6 21:40:39 1997 Return-Path: Received: by berlioz.nsc.com (4.1/SMI-4.1) id AA11688; Thu, 6 Mar 97 21:40:39 PST Date: Thu, 6 Mar 1997 21:33:18 -0800 (PST) From: Clifford Buttschardt To: Ed Larsen , John Yurek Cc: Laser Messages Subject: Re: FM Subcarriers on Lasers ! In-Reply-To: Message-Id: Mime-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: owner-laser@berlioz.nsc.com Precedence: bulk Hi John. I joined this group yesterday and this is one of the first messages printed. Great work and thanks for that. I have been fooling with some FM systems and never even thought of the optical bias system of increasing sensitivity. Using different frequnecies of bias light kind of reminds one of old fashion Maser technique. 73 Cliff Buttschardt K7RR >From owner-laser Fri Mar 7 06:36:11 1997 Return-Path: Received: by berlioz.nsc.com (4.1/SMI-4.1) id AA20672; Fri, 7 Mar 97 06:36:11 PST From: sjnoll@ix.netcom.com Date: Fri, 7 Mar 1997 08:30:16 -0600 (CST) Message-Id: <199703071430.IAA11412@dfw-ix9.ix.netcom.com> Mime-Version: 1.0 Content-Type: text/plain Content-Transfer-Encoding: 7bit Subject: Photodetector bias via LEDs. Solar Cell receivers. To: laser@berlioz.nsc.com X-Mailer: SPRY Mail Version: 04.10.06.22 Sender: owner-laser@berlioz.nsc.com Precedence: bulk RE: using a LED to bias a detector. It is quite common in the industry to apply a DC reverse bias to a photodiode. This significantly reduces its capacitance and thus speeds the response. This is done at the expense of some added noise (i.e. "dark current".) There is an improvement in linearity, but probably not noticable for our uses. The bias voltage is not critical but must be kept under the breakdown voltage. The capacitance-reducing effects of bias should begin to be seen with biases as small as under a volt. Operating with a bias is called "photoconductive" mode, vs the unbiased "photovoltaic" mode. One rule of thumb is that bias is required for operation above 1/3 MHz. Again, there will be added noise. If you desire speed your first concern should be using a detector with a small active area. This is one reason why solar sells suck. Their capacitance is way too high. Also, the type of silicon they start with to make solar cells (ohm-cm) is not good for making detectors. Shining a LED, or other light source on the detector will induce a DC bias in itself. There is no "heterodyning" going on. A LED is far too un-monochromic for that. Make sure your bias supply is well filtered. Hardly any measurable current will be drawn by the photodetector. 73, Steve J. Noll | Ventura CA | WA6EJO | sjnoll@ix.netcom.com | http://www.netcom.com/~sjnoll/usedequip.html | http://www.netcom.com/~sjnoll/peltier.html >From owner-laser Fri Mar 7 13:30:42 1997 Return-Path: Received: by berlioz.nsc.com (4.1/SMI-4.1) id AA02853; Fri, 7 Mar 97 13:30:42 PST Message-Id: <199703072123.QAA02846@host-04.colby.edu> X-Sender: aballen@colby.edu X-Mailer: Windows Eudora Light Version 1.5.2 Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Date: Fri, 07 Mar 1997 16:23:29 -0500 To: laser@berlioz.nsc.com From: "Art Allen, KY1K" Subject: PMT sockets wanted Sender: owner-laser@berlioz.nsc.com Precedence: bulk Hi Everyone, I need some 12 pin PMT sockets for a Hamamatsu R1617 3/4 inch head on PMT. This socket looks like a 7 or 9 pin mini tube socket, except it has 12 pins. Actually, it has 13 pins, equally spaced in a circle, except that the 13th pin is not used (except for index purposes). I have 3 NEW, in the BOX R1617's, that I cannot use because I don't have sockets. The Hamamatsu part number is E974-13 (which includes divider string components). If someone has bare sockets, that is FB too. Thanks, Art, KY1K. >From owner-laser Fri Mar 7 18:31:54 1997 Return-Path: Received: by berlioz.nsc.com (4.1/SMI-4.1) id AA08612; Fri, 7 Mar 97 16:15:12 PST Date: Fri, 7 Mar 97 16:15:12 PST From: owner-laser Message-Id: <9703080015.AA08612@berlioz.nsc.com> >From owner-laser Fri Mar 7 19:26:26 1997 Return-Path: Received: by berlioz.nsc.com (4.1/SMI-4.1) id AA09573; Fri, 7 Mar 97 16:40:18 PST Date: Fri, 7 Mar 97 16:40:18 PST From: owner-laser Message-Id: <9703080040.AA09573@berlioz.nsc.com> >From owner-laser Fri Mar 7 20:26:26 1997 Return-Path: Received: by berlioz.nsc.com (4.1/SMI-4.1) id AA09937; Fri, 7 Mar 97 16:49:42 PST Date: Fri, 7 Mar 97 16:49:42 PST From: owner-laser Message-Id: <9703080049.AA09937@berlioz.nsc.com> >From owner-laser Fri Mar 7 21:26:30 1997 Return-Path: Received: by berlioz.nsc.com (4.1/SMI-4.1) id AA02730; Fri, 7 Mar 97 21:26:30 PST Date: Fri, 7 Mar 97 16:49:35 PST From: jmoss (Jim Moss) Message-Id: <9703080049.AA09931@berlioz.nsc.com> To: laser Subject: Re: FM Subcarriers on Lasers ! Sender: owner-laser@berlioz.nsc.com Precedence: bulk John, What kind of range do you seem to be getting using the 67KHz subcarrier? This same method is used on many TV remotes! N5XSA (Kevin) and I tried that method, and ended up washing it out. We setup a 0.82 mile path. There was some 10-15 MPH wind, and occasional streams of cars in the RX pattern. The cars made very interesting swishing sounds, and then whrrrrrrs. The voice modulation on the subcarrier sounded excellent at close range, but at the 0.82 mile path it was extremely distorted ( a smooth garbling rather than raspy) , and rarely copiable. We used no lenses in this experiment, just the PIN diode. Jim WB9AJZ/6 CM87xi Sunnvyale, CA >From owner-laser Fri Mar 7 22:47:50 1997 Return-Path: Received: by berlioz.nsc.com (4.1/SMI-4.1) id AA03517; Fri, 7 Mar 97 22:47:50 PST Date: Sat, 8 Mar 97 06:42:01 UT From: "John Yurek" Message-Id: To: "Laser Messages" Subject: FM Subcarriers on Lasers ! & Optical Biasing Sender: owner-laser@berlioz.nsc.com Precedence: bulk I tried to send this several times but keep getting some weird response! resend: must specify both '-l list' and '-h host' arguments at /home/share/majordomo/bin/resend line 69. 554 "|/usr/local/share/majordomo/bin/wrapper resend -p bulk -M 20000 -R -l laser -f laser-owner -h berlioz.nsc.com laser-outgoing"... unknown mailer error 2 So I'll try it again! ----- Steve: >Shining a LED, or other light source on the detector will induce a DC >bias in itself. There is no "heterodyning" going on. A LED is far too >un-monochromic for that. I am in 100% agreement with this! I only mentioned it because someone else suggested it. Since the detector is operating in a fairly linear part of it's curve it's also highly unlikely that anything is mixing. I think where he got the idea was when he noticed that the red LED was listed as 635 nm and I was using a He-Ne laser for these tests. However, as you pointed out the LED is pretty much a wide band noise source compared to the He-Ne laser and if it actually did mix with the He-Ne signal I would expect the result to be white noise! However, there still remains the following mystery: The red LED used to bias the detector produces better signal to noise ratio than the yellow or green LED! (Actually this may have nothing at all to do with color and may be related to some other characteristic of the different LEDs??? I never took the time to really investigate this.) In ALL cases tested here optical biasing produced better signal to noise ratio than any type of DC bias tried. (I did NOT check frequency response!) The signal seems to be about the same with either bias scheme but there is a marked drop in noise floor when switching from DC bias to optical biasing making the resulting signal to noise ratio higher. >Make sure your bias supply is well filtered. Hardly any measurable >current will be drawn by the photodetector. When my system is set up properly the detector is drawing a fair amount of current. When using a 12vdc supply and a 10 k load resistor the detector has to draw about 0.6 ma. When using a 4.7 k load it has to draw 1.2 ma. This of course assumes that you are biasing to 1/2 of the supply voltage which is where I usually run my system. As you pointed out the bias supply should be well filtered. I am using battery power! However, one point that may be overlooked here is that when using a subcarrier system the receiver is pretty much only sensitive to the selected frequency so you don't hear things like power supply hum or the buzz associated with man made 60 Hz lighting getting into the detector like you do when running a base band detector straight into an audio amp. John K3PGP@msn.com >From owner-laser Sat Mar 8 05:09:07 1997 Return-Path: Received: by berlioz.nsc.com (4.1/SMI-4.1) id AA06568; Sat, 8 Mar 97 05:09:07 PST Message-Id: <199703081307.IAA09911@host-04.colby.edu> X-Sender: aballen@colby.edu X-Mailer: Windows Eudora Light Version 1.5.2 Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Date: Sat, 08 Mar 1997 08:07:11 -0500 To: laser@berlioz.nsc.com From: "Art Allen, KY1K" Subject: optical biasing.... Sender: owner-laser@berlioz.nsc.com Precedence: bulk Hi Everyone... In the early days (my early days) of laser work, I started out with a Crap Shack IR phototransistor and a 741 op amp rx, built on perf board (no lenses). I built up a 555 multivibrator driving a red LED and used it as a transmitter for real short testing ranges. At the time, I was using the LONG hallway in the apartment as a test range. I was interested in seeing IF this marginal setup and my QRP HE-NE would meet the 1 km suggested minimum in the vhf contest rules. During the testing, I used a flashlight to see in the dark. I noticed that when any of the flashlight beam fell on the RX, that the RX range increased from about 3 feet up to 10 to 12 feet. Of course, the background noise came up too, but the signal to noise ratio was WAY better with the optical biasing. I finally tried mounting a red LED so that it pointed towards the phototransistor and had a pot in series to control the current to the LED. I found that the setting of the LED intensity didn't make MUCH difference in the actual performance and I concluded that a fixed 220 ohm series resistor could do just as well as the pot did. Anyway my little QRP TX was able to be heard about 3 to 4 times the distance IF the LED was powered up. I chalked this up to the Crap Shack device itself, it didn't have a third terminal so that I couldn't bias the device via resistors on the base lead. I never pursued the matter further, as I expected to move up to photodiodes soon anyway due to the phototransistors .003 inch by .003 inch active area, which limits their uselfullness (hard to get all the light from a lens to focus on that small of an area hi hi). But, at the time I quit dubbing around with these, I ASSUMED that I could achieve the same effect by electrically biasing the base lead of the phototransistor (if there was one). Incidently, I found that these simple RX's COULD hear my 1 mw @ 2.2 mrad laser at a distance of 1 mile (without the use of light gathering lenses). We used some of these inexpensive RX setups to make some short range laser Q's during a couple of the vhf contests later. 73 and GL..Art... >From owner-laser Sat Mar 8 05:38:17 1997 Return-Path: Received: by berlioz.nsc.com (4.1/SMI-4.1) id AA06775; Sat, 8 Mar 97 05:38:17 PST Date: Sat, 8 Mar 1997 08:35:20 -0500 (EST) Message-Id: <2.2.16.19970308090022.282fd536@mail.snet.net> X-Sender: paulc@mail.snet.net X-Mailer: Windows Eudora Pro Version 2.2 (16) Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" To: laser@berlioz.nsc.com From: "Paul A. Cianciolo" Subject: Odd readings... Sender: owner-laser@berlioz.nsc.com Precedence: bulk Hello all, I have been monitoring a strobe off of the CH 20 TV station about 21 miles away, for quite sometime now. I have noticed that there are some pulses that show up that go in a negative direction. How is it possible for a light source to produce a positive going voltage on 1 pulse and negative going on the some others? is this a ringing problem in my amplifier system? I am very curios 73's PaulC KB1RP >From owner-laser Sat Mar 8 06:20:52 1997 Return-Path: Received: by berlioz.nsc.com (4.1/SMI-4.1) id AA07096; Sat, 8 Mar 97 06:20:52 PST From: sjnoll@ix.netcom.com Date: Sat, 8 Mar 1997 08:16:30 -0600 (CST) Message-Id: <199703081416.IAA27436@dfw-ix8.ix.netcom.com> Mime-Version: 1.0 Content-Type: text/plain Content-Transfer-Encoding: 7bit Subject: Biasing photodiodes To: laser@berlioz.nsc.com X-Mailer: SPRY Mail Version: 04.10.06.22 Sender: owner-laser@berlioz.nsc.com Precedence: bulk If you are biasing a photodiode and measure any bias current flow more than nanoamps (in the dark), then you need to check that you aren't FORWARD biasing the detector - something you don't want to do! Always _reverse_ bias by putting a positive voltage on the cathode, or, a negative voltage on the anode. The voltage is not at all critical - just stay under the breakdown voltage - typically many tens of volts. 73, Steve J. Noll | Ventura CA | WA6EJO | sjnoll@ix.netcom.com | http://www.netcom.com/~sjnoll/usedequip.html | http://www.netcom.com/~sjnoll/peltier.html >From owner-laser Sat Mar 8 08:27:51 1997 Return-Path: Received: by berlioz.nsc.com (4.1/SMI-4.1) id AA08280; Sat, 8 Mar 97 08:27:51 PST Message-Id: <199703081625.LAA17279@host-04.colby.edu> X-Sender: aballen@colby.edu X-Mailer: Windows Eudora Light Version 1.5.2 Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Date: Sat, 08 Mar 1997 11:26:01 -0500 To: laser@berlioz.nsc.com From: "Art Allen, KY1K" Subject: mouse tech talk? Sender: owner-laser@berlioz.nsc.com Precedence: bulk Hey Everyone... I'm convinced (after alot of thought), that the only way to go on the aiming issue is to use a raster system for initial alignment of the TX. Since the HUMAN EYES have many magnitues of sensitivity advantage over the best detectors, they can be used to detect the presence of the beam even though it sweeps by the target quickly. Towards that end, I was trying to think of the BEST interface to CONTROL the raster system. I am thinking along the lines of a stepper motor with a gear reduction box-mount the laser pen right on the shaft and have some limit switches to automatically reverse the direction of the stepper motor once it reaches the end of its sweep-and visa versa. This should take care of the azimuth. Elevation could be manually swept by hand until someone hollers from the other end of the path. Perhaps a stepper motor isn't necessary, a 1 rpm dc motor/gearbox might work just as well. Slow down the sweeping speed when someone hollers from the target... Anyway, I'm babbeling..sorry.... Using the stepper motor for the raster is the direction I'd like to proceed in (for now). Computer control of the stepper motor would be OK, but I have no desire to drag along a 6 or 8 pound PC along, just to provide this function. I'm thinking I want to use my computer mouse (microsoft 2 button type) to control the sweeping and build an interface unit between it and the stepper moter controller. So, I labotomized my mouse earlier this AM trying to figure out how it works (it needed a cleaning REAL BADLY anyway). It has some small interuptor wheels and conventional LED TX/phototransistor receivers to detect mouse motion. It has a custom chip in it-a 20 pin dip. BUT, exen after looking at it from the inside out, I still can't figure out how the mouse works. It has 4 wires coming into it, 2 of them have +5 vdc and one is ground. The fourth wire floats at about 28 mv dc. I'm guessing that one of the 5 v wires is just a pullup from the computer. I cannot detect any changing of levels with my dc volt meter. So, my guess is that the chip inside the mouse is a multiplex type chip, with 2 wires for the output, all MULTIPLEXED. Upon further examination (heres the real mystery) I began to wonder HOW the computer knows which direction the mouse is being pushed in!? It only has the pulse output from the interruptor to go by.. So, how does the blasted thing know whether that wheel is turning cw or ccw?? Any technical info about the mouse and how it operates would be appreciated. GL...Art, KY1K. >From owner-laser Sat Mar 8 12:26:24 1997 Return-Path: Received: by berlioz.nsc.com (4.1/SMI-4.1) id AA11980; Sat, 8 Mar 97 12:26:24 PST From: sjnoll@ix.netcom.com Date: Sat, 8 Mar 1997 14:22:03 -0600 (CST) Message-Id: <199703082022.OAA17027@dfw-ix15.ix.netcom.com> Mime-Version: 1.0 Content-Type: text/plain Content-Transfer-Encoding: 7bit Subject: RE: Odd Readings... To: laser@berlioz.nsc.com X-Mailer: SPRY Mail Version: 04.10.06.22 Sender: owner-laser@berlioz.nsc.com Precedence: bulk "Negative Frequency" has been a long-kept Government secret. There's another entire spectrum below zero Hertz. It was only a matter of time before one of us Hams stumbled across it! I'm just surprised that Wayne Green didn't discover it first. I think it's like you said - a ringing, or like response in your amplifier. 73, Steve J. Noll | Ventura CA | WA6EJO | sjnoll@ix.netcom.com | http://www.netcom.com/~sjnoll/usedequip.html | http://www.netcom.com/~sjnoll/peltier.html >From owner-laser Sun Mar 9 07:40:54 1997 Return-Path: Received: by berlioz.nsc.com (4.1/SMI-4.1) id AA28077; Sun, 9 Mar 97 07:40:54 PST Date: Sun, 9 Mar 97 15:34:27 UT From: "John Yurek" Message-Id: To: "Laser Messages" Subject: FM Subcarriers on Lasers ! & Optical Biasing Sender: owner-laser@berlioz.nsc.com Precedence: bulk Steve: >If you are biasing a photodiode and measure any bias current flow more >than nanoamps (in the dark), then you need to check that you aren't >FORWARD biasing the detector - something you don't want to do! I thought there was some confusion on this! I am NOT reverse biasing the detector.. I am FORWARD baising the detector but using light to do it. I don't know why this is working so well for me, all I know that it is and that's why I offered the idea here so more people could experiment with it. Remember when I do this I also decrease the series resistor to the detector to a fairly low value of something like 4.7k or 10 k ohms which is quite different from the megaohm range that I usually see. When this resistor is made this small it helps to swamp the shunt capacitance of the detector thus improving frequency response. However, when the series resistor is made this small sensitivity will suffer. When the detector is then FORWARD biased with the red LED the sensitivity improves to better than it was with the high value series resistor with the added benefit that the high frequency response is now also improved. I have tried this with both diode detector and photo transistors. Unfortunately all devices were obtained at hamfests and were considered junk box items so I don't have a clue as to exactly what they are. Of course some exhibit this effect more than others so they key word here is to experiment! This seems to go against anything that I've ever seen in the literature. As you pointed out most detectors are REVERSE biased to improve frequency response. I am using a small value resistor to swamp the internal capacitance of the detector to improve the frequency response and optical biasing to increase sensitivity. John K3PGP@msn.com >From owner-laser Sun Mar 9 07:41:00 1997 Return-Path: Received: by berlioz.nsc.com (4.1/SMI-4.1) id AA28083; Sun, 9 Mar 97 07:41:00 PST Date: Sun, 9 Mar 97 15:33:42 UT From: "John Yurek" Message-Id: To: "Laser Messages" Subject: FM Subcarriers on Lasers ! & Optical Biasing Sender: owner-laser@berlioz.nsc.com Precedence: bulk Jim: >What kind of range do you seem to be getting using the 67KHz subcarrier? >This same method is used on many TV remotes! Actually most remotes seem to run around 44 Khz. Yes the idea is similar but you are comparing a wideband short range digital system to a narrow band long range FM system! The range I am getting is at least equal to the wideband 800 Hz cw method. With proper IF filtering I would expect the subcarrier method to produce somewhat better range than the wideband cw method simply because it is a narrow band system. I don't know what the maximum range is though because as you know it's difficult to find long range line of sight paths to play with. However, in all cases if the 800 Hz tone could be heard the FM system worked just fine. The most difficult path that I've tried this on so far is an indirect path involving a communications tower as a reflector. This tower is approx.. 3 miles from me and about 2 miles from the other station. Unfortunately we do NOT have line of sight between us other than this tower which is why we tried it. The tower has nine white vertical radomes covering antennas at the top of the tower. These white surfaces seem to reflect (actually the proper term is probably scatter!) laser beams very well. This tower doesn't have any lighting on it at all which makes it impossible to find in the dark but eliminates any noise pulses from blinking lights or strobes! I might ad that on this path if we don't use optical biasing on the detectors we don't hear anything at all! Although you didn't mention what you are using for a TX I assume that it's some kind of laser pen. I don't have a lot of experience with these because of the expense involved but if you are experiencing short range problems and distortion I would suggest that you take a very close look at the power/current regulator circuit that feeds the laser diode. Most of these are designed for a CW system and don't work properly when fed with a high frequency square wave. They seem to behave fairly well at 800 hz but when you get up into the 20 to 100 Khz region they start to round off the square wave and make it look more like a triangle wave. The result is that the laser diode doesn't develop full power or worse yet never even makes it to the laser threshold current. If the latter happens you end up with a very expensive bright LED because there is no laser action at all! I suggest that you do some close in power measurements. Setup the system as a CW system (no modulation at all!). Make sure you are NOT saturating the detector. Feed a very low frequency square wave into the TX. Start out with something below 3 hz! Look at the detector with an oscilloscope. You should see the laser switching from full on to full off. There should be no ramping or overshoot of the power level at turn on! Now start to increase the frequency. My guess is that sometime before you reach the 20 to 100 Khz range your laser will start to decrease in power and the square wave will become distorted looking more like a distorted triangle wave. Keep in mind that a triangle wave driving a detector into saturation will produce a square wave so again I must emphasize that you make sure that you are not saturating the detector. If necessary bounce the beam off a semi reflector to get the power level / power density down! You may need to scrap the internal power/current regulator and design a new one that can handle the high frequency square wave properly. I have had no problem modulating laser diodes directly up to at least 10 Mhz once I did this. In all cases I was feeding the laser diode a 50% duty cycle square wave. This is NOT a pulse width modulated system where the duty cycle changes with modulation. I am frequency modulating the signal feeding the laser diode. The duty cycle never changes. John K3PGP@msn.com >From owner-laser Sun Mar 9 18:22:52 1997 Return-Path: Received: by berlioz.nsc.com (4.1/SMI-4.1) id AA11248; Sun, 9 Mar 97 18:22:52 PST Date: Sun, 9 Mar 1997 21:20:09 -0500 (EST) Message-Id: <2.2.16.19970309214453.089792e6@mail.snet.net> X-Sender: paulc@mail.snet.net X-Mailer: Windows Eudora Pro Version 2.2 (16) Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" To: laser@berlioz.nsc.com From: "Paul A. Cianciolo" Subject: Stacking LEDS as a source Sender: owner-laser@berlioz.nsc.com Precedence: bulk Hello All, I have built (a few years ago) an array of LEDS that is 512 in number. The LEDS all came out of discarded remote controls that I acquired while working at a cabletv company. Is stacking leds like stacking yagis? Does the overall pattern change.. or is it stay the same as 1 LED because the arrray is not phased? I assume that the diodes all melt into 1 light source at some distance. Would spacing the diodes differently have had any effect on the pattern. The diodes run at 940nm I believe and have a 3db beamwidth of 17 degrees. I will check this out with my security camera that see well into the IR range. How does the power density of this array compare with a 5 mw laser at distance? It sure is alot easier to point... Thanks for any info 73's PaulC KB1RP >From owner-laser Mon Mar 10 04:20:58 1997 Return-Path: Received: by berlioz.nsc.com (4.1/SMI-4.1) id AA24918; Mon, 10 Mar 97 04:20:58 PST Date: Mon, 10 Mar 1997 07:17:33 -0500 (EST) Message-Id: <2.2.16.19970310074211.08d7e88e@mail.snet.net> X-Sender: paulc@mail.snet.net X-Mailer: Windows Eudora Pro Version 2.2 (16) Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" To: laser@berlioz.nsc.com From: "Paul A. Cianciolo" Subject: Need to ID these leds Sender: owner-laser@berlioz.nsc.com Precedence: bulk >Date: Sun, 09 Mar 1997 09:01:14 >To: laser list >From: "Paul A. Cianciolo" >Subject: Need to ID these leds > >Hello Folks. > >Can anyone help me id the specs on these Toshiba LEDS? > >TLRA179 >TRLC180ap > >any help appreciated > >Thank you > > 73's PaulC KB1RP >From owner-laser Mon Mar 10 05:50:06 1997 Return-Path: Received: by berlioz.nsc.com (4.1/SMI-4.1) id AA26968; Mon, 10 Mar 97 05:50:06 PST From: sjnoll@ix.netcom.com Date: Mon, 10 Mar 1997 07:45:10 -0600 (CST) Message-Id: <199703101345.HAA04626@dfw-ix8.ix.netcom.com> Mime-Version: 1.0 Content-Type: text/plain Content-Transfer-Encoding: 7bit Subject: Stacking LEDs To: laser@berlioz.nsc.com X-Mailer: SPRY Mail Version: 04.10.06.22 Sender: owner-laser@berlioz.nsc.com Precedence: bulk Boy - stacking 512 LEDs, that sounds like an ambitious project! The light from a LED is incoherent. It is not all in phase like light is from a laser. Grouping LEDs will simply increase the output. Spacing shouldn't matter. You can pulse LEDs at a much higher current than their CW DC rating and get more light out, but I don't know what the limits are. To get max smoke in one direction it would be worthwhile to aim them individually using a IR viewing device, or video camera that sees IR. 73, Steve J. Noll | Ventura CA | WA6EJO | sjnoll@ix.netcom.com | http://www.netcom.com/~sjnoll/usedequip.html | http://www.netcom.com/~sjnoll/peltier.html >From owner-laser Mon Mar 10 07:36:20 1997 Return-Path: Received: by berlioz.nsc.com (4.1/SMI-4.1) id AA29472; Mon, 10 Mar 97 07:36:20 PST Message-Id: <199703101533.KAA18116@host-04.colby.edu> X-Sender: aballen@colby.edu X-Mailer: Windows Eudora Light Version 1.5.2 Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Date: Mon, 10 Mar 1997 10:33:28 -0500 To: "Paul A. Cianciolo" From: "Art Allen, KY1K" Subject: Re: Stacking LEDS as a source Cc: laser@berlioz.nsc.com Sender: owner-laser@berlioz.nsc.com Precedence: bulk Hi Paul, and the group... I ran the numbers for this example. I assumed each one of the diodes had a 5 mw output @ .30 rad beamwidth. I compared that to a single 5 mw @ .001 rad HE-NE. I assumed perfect optics and perfect atmospheric conditions. I used e-10w for a minimum detectable receiver power (about the same as a solid state photodiode rx). I used a 4 inch round lens for a RX ant. For the 512 diode array, I get 33.7 km. For the single HE-NE, I get 632 km. For newbees, this is not a misprint-that beam scatters FAST and at 17 degrees, that signal goes away FAST also. Hope this helps. Enjoy...Art, KY1K. At 09:20 PM 03/09/1997 -0500, you wrote: >Hello All, > >I have built (a few years ago) an array of LEDS that is 512 in number. The >LEDS all came out of discarded remote controls that I acquired while working >at a cabletv company. Is stacking leds like stacking yagis? Does the >overall pattern change.. or is it stay the same as 1 LED because the arrray >is not phased? I assume that the diodes all melt into 1 light source at >some distance. > >Would spacing the diodes differently have had any effect on the pattern. >The diodes run at 940nm I believe and have a 3db beamwidth of 17 degrees. I >will check this out with my security camera that see well into the IR range. > >How does the power density of this array compare with a 5 mw laser at distance? > >It sure is alot easier to point... > >Thanks for any info > > >73's >PaulC KB1RP > > > >From owner-laser Mon Mar 10 08:12:37 1997 Return-Path: Received: by berlioz.nsc.com (4.1/SMI-4.1) id AA00678; Mon, 10 Mar 97 08:12:37 PST From: Rusty Carruth Message-Id: <199703101612.JAA14911@user1.inficad.com> Subject: hi! To: laser@berlioz.nsc.com Date: Mon, 10 Mar 1997 09:12:50 -0700 (MST) X-Mailer: ELM [version 2.4 PL25] Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: owner-laser@berlioz.nsc.com Precedence: bulk Hi. I am Rusty Carruth, n7ikq. I just joined the laser list (probably pretty obvious, eh?), thought I'd just let everyone know who I am. I've been playing with laser communication off and on for a couple of years (yikes! has it been that long???). So far we've managed 2.5 miles max two-way, inside the city (for testing and learning). One-way we made about 10 miles - one end was on a mountiantop with lots of nice red lights for the other end to sight on - my end had to try to find the 'fox' amid LOTS of lights near the edge of the city.... Modulation scheme - the famous fan in front of the laser (He-Ne), keying is by turning the laser on and off (not going for cw speed record, can you tell? :-) Rusty, aka rusty@indirect.com, rusty@descomp.com, n7ikq@qso.com, rustyc@inficad.com, and a host of others... >From owner-laser Mon Mar 10 08:48:52 1997 Return-Path: Received: by berlioz.nsc.com (4.1/SMI-4.1) id AA01967; Mon, 10 Mar 97 08:48:52 PST Date: Mon, 10 Mar 97 08:48:48 PST From: jmoss (Jim Moss) Message-Id: <9703101648.AA01961@berlioz.nsc.com> To: laser Subject: NEED ID TO THESE LEDS Sender: owner-laser@berlioz.nsc.com Precedence: bulk From: "Paul A. Cianciolo" Subject: Need to ID these leds Hello Folks. Can anyone h*e*l*p me id the specs on these Toshiba LEDS? TLRA179 TRLC180ap any help appreciated Thank you 73's PaulC KB1RP PS: don't use the word *HELP* in your text, or majordomo spits it out! Jim (WB9AJZ) >From owner-laser Mon Mar 10 08:59:29 1997 Return-Path: Received: by berlioz.nsc.com (4.1/SMI-4.1) id AA02376; Mon, 10 Mar 97 08:59:29 PST Date: Mon, 10 Mar 97 08:59:25 PST From: jmoss (Jim Moss) Message-Id: <9703101659.AA02370@berlioz.nsc.com> To: laser@berlioz.nsc.com Subject: stepper aiming system Sender: owner-laser@berlioz.nsc.com Precedence: bulk RESENDING: Date: Fri, 7 Mar 97 16:40:14 PST From: jmoss (Jim Moss) Message-Id: <9703080040.AA09563@berlioz.nsc.com> To: laser Subject: stepper aiming system Art asked me if this method is faster than others. Here's my short answer.. I'm working on an aiming primer now. For a 1mR beam and 20 mile distance, based on my experiences: Method Time to align Notes ------ ------------- ----- handheld infinite or infinitely short time on target good for fun Tripod 30-45 minutes shakes and sticks 2-5 minutes for down the block! scatter of the street is easy! Tripod+jig 10-20 minutes shakes + bumps Tripod+stepper 10 min??? haven't tried it at distance yet! less shakes? Base + Stepper 5-10 minutes? solid? Base/step/ccd 1 min? solid, fast allows servoing The stepper is still not all that fast because it is semi-automatic: 1) course alignment to target (to within 2 degrees = 35 mR) 2) scan sequencing a) right now I am doing a "raster" scan, because it's easy to program! b) circular/spiral would be more efficient c) have to wait for RX to say it is "seen". So you can only move at maybe 2 mR per second? 3) Fine tune with single keystrokes from there. 1mR per second? The CCD idea is what the military uses. CCD acquires target, and servos the beam in, then quadrant detectors narrow it more, then communication begins. I can see I need to get out on the hill and try the stepper!! Jim WB9AJZ/6 CM87xi Sunnyvale, CA ----- End Included Message ----- >From owner-laser Mon Mar 10 09:03:15 1997 Return-Path: Received: by berlioz.nsc.com (4.1/SMI-4.1) id AA02522; Mon, 10 Mar 97 09:03:15 PST Date: Mon, 10 Mar 97 09:03:13 PST From: jmoss (Jim Moss) Message-Id: <9703101703.AA02516@berlioz.nsc.com> To: laser Subject: Re: FM Subcarriers on Lasers ! Sender: owner-laser@berlioz.nsc.com Precedence: bulk ----- Begin Included Message ----- >From PaulC@snet.net Sat Mar 8 05:45:51 1997 Date: Sat, 8 Mar 1997 08:45:56 -0500 (EST) X-Sender: paulc@mail.snet.net X-Mailer: Windows Eudora Pro Version 2.2 (16) Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" To: jmoss@berlioz.nsc.com (Jim Moss) From: "Paul A. Cianciolo" Subject: Re: FM Subcarriers on Lasers ! Content-Length: 1442 Hello Jim, Interesting comments on the .82 mile path. I have never seen a 67 khz tv remote. I have seen lots of different ones running from 38 khz to 42 khz with most around 40 khz. I have a number of cable box, VCR, tv set front ends and they all run around 40 khz,,,. Any Idea why 40 khz was chosen? Lots of Ultrasonic stuff works at 40 khz also. I wonder if 40 being 2 x 20 the generally accepted highest freq a human can was chosen? Man if you want to see multipath I did a 200' 40khz acoustic path a year ago with low power and a parabolic on each end wow a .5 mph wind will kill your signal.. pushes right out of the path. Parabolics work well only when is very still and temp is very constant.. At 04:49 PM 3/7/97 PST, you wrote: >John, >What kind of range do you seem to be getting using the 67KHz subcarrier? >This same method is used on many TV remotes! > >N5XSA (Kevin) and I tried that method, and ended up washing it out. >We setup a 0.82 mile path. There was some 10-15 MPH wind, and occasional >streams of cars in the RX pattern. The cars made very interesting swishing >sounds, and then whrrrrrrs. The voice modulation on the subcarrier sounded >excellent at close range, but at the 0.82 mile path it was extremely >distorted ( a smooth garbling rather than raspy) , and rarely copiable. >We used no lenses in this experiment, just the PIN diode. > >Jim >WB9AJZ/6 CM87xi Sunnvyale, CA > > 73's PaulC KB1RP ----- End Included Message ----- >From owner-laser Mon Mar 10 10:00:15 1997 Return-Path: Received: by berlioz.nsc.com (4.1/SMI-4.1) id AA05040; Mon, 10 Mar 97 10:00:15 PST Date: Mon, 10 Mar 97 10:00:12 PST From: jmoss (Jim Moss) Message-Id: <9703101800.AA05034@berlioz.nsc.com> To: laser Subject: PMT experiments Sender: owner-laser@berlioz.nsc.com Precedence: bulk Over the weekend I powered up one of the PMT's that I found surplus. Hamamatsu H957-05 with built in PS + resistors. I powered it at 13v, and used a 10K resistor to ground on the control line. The output was fed into an opamp (supply 0, 13v) with 1 M Ohm feedback and other terminal grounded. Output was fed thru .1uF cap to an audio amp. So as not to overload the PMT, I had a piece of black electrical tape over the openning. Even with the tape in place, I was able to detect laser reflections off a wall 10 feet away! Later in the evening when all the light could be turned off, I removed the tape and experimented with various gains (still had light coming in from the outdoor street lights). Can quite easily copy 800 Hz signals scattering off walls (<3mW 670nM, 1mR) even if the laser was behind and aimed behind/away the PMT. (scattering off walls behind) I am amazed at the sensitivity! I verified results by moving the laser on the wall, and off into a hallway, the signal went away. (I did this to eliminate possible feedback from the oscillator into the RX, and insure signal was thru the light!) At the end of the evening I put a 630-680 filter on the tube, and noted a marked decrease in 60 Hz noise, but still there. The LM386, does an excellent job of filtering out 60 Hz noise (my audio amp)... gives about 40dB notch there. Jim WB9AJZ/6 PS: There were some issues with the reflector on Friday night... don't know exactly what caused it, but it was OK on Saturday. Probably associated with a backup procedure or network work inside. Jim >From owner-laser Mon Mar 10 12:54:00 1997 Return-Path: Received: by berlioz.nsc.com (4.1/SMI-4.1) id AA12105; Mon, 10 Mar 97 12:54:00 PST Message-Id: <199703102014.PAA17601@host-04.colby.edu> X-Sender: aballen@colby.edu X-Mailer: Windows Eudora Light Version 1.5.2 Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Date: Mon, 10 Mar 1997 15:14:43 -0500 To: laser@berlioz.nsc.com From: "Art Allen, KY1K" Subject: brain teaser... Sender: owner-laser@berlioz.nsc.com Precedence: bulk Hi Everyone, Here's a good one for the group..... If I stand on the moon or other similar astronomical body without atmosphere and shine my 5 mw at 1 mrad laser into outer space... At what distance would the intensity of the Sun appear equal to the intensity of the Sun (as viewed from that distance)?? Would my tiny laser EVER equal the Sun's intensity? >From owner-laser Mon Mar 10 13:16:32 1997 Return-Path: Received: by berlioz.nsc.com (4.1/SMI-4.1) id AA13086; Mon, 10 Mar 97 13:16:32 PST Date: Mon, 10 Mar 97 13:16:30 PST From: jmoss (Jim Moss) Message-Id: <9703102116.AA13080@berlioz.nsc.com> To: laser Subject: laser comm articles Sender: owner-laser@berlioz.nsc.com Precedence: bulk A list of references: QST Apr 89 p74 Info on range equation, includes a graph for 1mW HeNe QST Jan 89 p86 Notes on KY7B-WA7LYI 442nM 95.6 Mile contact CQ Jan 97 Optoelectronics primer part 1 - intro CQ Feb 97 Opto primer part 2 - Tx CQ Mar 97 Opto Primer part 3 - Rx CQ Apr 97 Opto Primer part 4 - lenses Laser Focus World JAN 97 BACK TO BASICS FEB 97 BACK TO BASICS MAR 97 BACK TO BASICS Please let me know if there are any corrections/additions. Will add to the web page in a couple days. Jim WB9AJZ/6 >From owner-laser Mon Mar 10 13:42:19 1997 Return-Path: Received: by berlioz.nsc.com (4.1/SMI-4.1) id AA14179; Mon, 10 Mar 97 13:42:19 PST Date: Mon, 10 Mar 97 13:42:16 PST From: jmoss (Jim Moss) Message-Id: <9703102142.AA14173@berlioz.nsc.com> To: laser Subject: laser downtime 3/10 6-6:15 PM PST Sender: owner-laser@berlioz.nsc.com Precedence: bulk >From owner-laser Wed Mar 12 09:35:26 1997 Return-Path: Received: by berlioz.nsc.com (4.1/SMI-4.1) id AA13665; Wed, 12 Mar 97 09:35:26 PST From: daveaa1a@ssih.com Date: Wed, 12 Mar 1997 12:08:53 -0500 Message-Id: <199703121708.MAA05379@ssih.com> Mime-Version: 1.0 Content-Type: text/plain Content-Transfer-Encoding: 7bit Subject: Congratulations To: laser@berlioz.nsc.com X-Mailer: SPRY Mail Version: 04.00.06.17 Sender: owner-laser@berlioz.nsc.com Precedence: bulk In every worthwhile endeavor there seems to be leaders or those who dare to jump out and be interested in finding out and making improvements on whatever: My re-interest in Laser Comms was triggered by in part by, Steve Knoll who very unselfishly gave me his paperwork and his time way back.. More recently I read John Yurek K3PGP who answered my quest for more bandwidth and diode biasing.. not to mention the real neat VLF master mixer trick.. Right on John.. How about Jim of berlioz who has been the glue to keep it all together .. HORRAY U GUYS.. How about we unanimously elect them Honorary Leadership before some clod of a control freak or someone who needs a lot of rules comes along..??.. Looks like it will soon be hilltopping weather so have dusted off the old 10ghz transverter and the laser junk.. Am QRV - QRU from Plymouth County FN51/41/42.. Transmitter: 650/670/ 5mw. diodes A1-A2-A3 FM sub at 67khz. (Video soon) Aimed in X/Y with micrometers and 4X scope all tied together with modulators etc.. Receiver: 4" lense / Pin / ultra low noise pre-amp / DBmixer (vlf conv.) into ic-706 receiver.. IF is 4 mhz. 10 ghz. (voice link for laser schtuff) 1' dish transverter in small PVC box 1 db front end, 250 mw. out.. Ic-706 is the IF at 146 mhz and since the receiver is general coverage, lets me monitor brick frequency.. Goals: take my 10-9th time base and go CCW with the Subcarrier on laser, use VE2IQ Coherent (BPSK) and see what can be done.. QTH: Am located in Plymouth County Mass. and have a few good shots from around here; Myles Standish Monument in Duxbury to Manomet Point to P'Town.. One shot over to Plymouth (my best DX at 12 miles) sounded like 40 over 9... Am QRU and QRV from Marshfield, Mass FN42 and FN41/51 73 de Dave Riley AA1A daveaa1a@ssih.com >From owner-laser Wed Mar 12 13:06:37 1997 Return-Path: Received: by berlioz.nsc.com (4.1/SMI-4.1) id AA19270; Wed, 12 Mar 97 13:06:37 PST Date: Wed, 12 Mar 97 13:06:35 PST From: jmoss (Jim Moss) Message-Id: <9703122106.AA19258@berlioz.nsc.com> To: laser Subject: CCW Sender: owner-laser@berlioz.nsc.com Precedence: bulk Dave, Tell us more about CCW (Coherent CW)? or the VE2IQ Coherent (BPSK). I've been considering use of high speed digital as well. But have stuck with baseband to be compatible with IRDA standards for IR comm between computers, etc. Jim WB9AJZ/6 Sunnyvale, CA CM87xi (CN70xa for June) >From owner-laser Wed Mar 12 13:56:26 1997 Return-Path: Received: by berlioz.nsc.com (4.1/SMI-4.1) id AA20849; Wed, 12 Mar 97 13:56:26 PST Date: Wed, 12 Mar 1997 13:44:35 -0800 (PST) From: Clifford Buttschardt To: daveaa1a@ssih.com Cc: laser@berlioz.nsc.com Subject: Re: Congratulations In-Reply-To: <199703121708.MAA05379@ssih.com> Message-Id: Mime-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: owner-laser@berlioz.nsc.com Precedence: bulk Hey Dave! Here we go again! Not only do we meet on 500 KHz, then 1750 meters but now 650 nMeters! Hey you have a very good idea here using coherent detection for laser. I wondered if it might be possilbe to use some sort of subcarrier----say 60 Khz, as a reference that can be demodulated on the receive end, without using a frequency reference. Good ideas here those! 73 Cliff Buttschardt K7RR ex W6HDO >From owner-laser Wed Mar 12 19:38:50 1997 Return-Path: Received: by berlioz.nsc.com (4.1/SMI-4.1) id AA03709; Wed, 12 Mar 97 19:38:50 PST From: sjnoll@ix.netcom.com Date: Wed, 12 Mar 1997 21:33:39 -0600 (CST) Message-Id: <199703130333.VAA23246@dfw-ix9.ix.netcom.com> Mime-Version: 1.0 Content-Type: text/plain Content-Transfer-Encoding: 7bit Subject: Toshiba LED i.d. To: laser@berlioz.nsc.com X-Mailer: SPRY Mail Version: 04.10.06.22 Sender: owner-laser@berlioz.nsc.com Precedence: bulk I checked two Toshiba opto catalogs at work yesterday for the TLRA179 & TLRC180ap and struck out. They are legit looking Toshiba LED numbers. Any idea if they are real new or real old models? 73, Steve J. Noll | Ventura CA | WA6EJO | sjnoll@ix.netcom.com | http://www.netcom.com/~sjnoll/usedequip.html | http://www.netcom.com/~sjnoll/peltier.html >From owner-laser Thu Mar 13 05:44:55 1997 Return-Path: Received: by berlioz.nsc.com (4.1/SMI-4.1) id AA19223; Thu, 13 Mar 97 05:44:55 PST From: daveaa1a@ssih.com Date: Thu, 13 Mar 1997 08:29:05 -0500 Message-Id: <199703131329.IAA08133@ssih.com> Mime-Version: 1.0 Content-Type: text/plain Content-Transfer-Encoding: 7bit Subject: Re: CCW To: jmoss@berlioz.nsc.com (Jim Moss) Cc: laser@berlioz.nsc.com, microwaveeast@wa1mba.org, sbill@ietc.ca/home/sbill.htm In-Reply-To: <9703122106.AA19258@berlioz.nsc.com> X-Mailer: SPRY Mail Version: 04.00.06.17 Sender: owner-laser@berlioz.nsc.com Precedence: bulk >Tell us more about CCW (Coherent CW)? or the VE2IQ Coherent (BPSK). Hi Jim, I just spent the LOWFER (160-190khz) season working NO-ONE on CCW and BPSK but am not giving up. Twelve years ago, random QSO's were common on that band and we did RTTY and other digital modes... To keep a real good idea alive I decided to move the VE2IQ bpsk/ccw scheme up to HF-VHF and Laser and see if anyone wants to play there. I cannot get my brick to stay within 10hz at 10ghz so will try later on that.(building PLL).. A visit to VE2IQ, Bill deCarle's internet spot ( www.ietc.ca/home/sbill.htm ) and selecting 'Landline BBS' will make several neat programs available for the downloading. FFT.ZIP is a audio spectrum DOS pgm. for the PC COHERENT.ZIP is the latest BPSK data program for the PC with 3 split screen panels and full duplex operation. The older version (included) still has the CCW terminal. UTILITY.ZIP is a zero beat utility that lets you determine carier frequency to within 1 hz. VERY impressive for frequency measurements and setting your transceiver to the right spot. Bill sells a dandy kit that demodulates audio into RS232. It's a BARGAIN.. I took a serial A/B switch, removed the 'B' connector, installed Bill's pc board within and replaced the 'B' connector with RCA jacks, now have NORMAL SERIAL or COHERENT using the same port on the PC. There are other neat programs there to download and try such as a Beacon Keyer etc.. I hear that the above can be found on HF 160 or 80 but haven't found where as yet. Happy Experimenting.. 73 de Dave Riley - AA1A - Marshfield, Mass... >From owner-laser Thu Mar 13 06:03:25 1997 Return-Path: Received: by berlioz.nsc.com (4.1/SMI-4.1) id AA19636; Thu, 13 Mar 97 06:03:25 PST From: daveaa1a@ssih.com Date: Thu, 13 Mar 1997 08:47:24 -0500 Message-Id: <199703131347.IAA08210@ssih.com> Mime-Version: 1.0 Content-Type: text/plain Content-Transfer-Encoding: 7bit Subject: Re: CCW To: laser@berlioz.nsc.com Cc: bill@ietc.ca, microwaveeast@wa1mba.org X-Mailer: SPRY Mail Version: 04.00.06.17 Sender: owner-laser@berlioz.nsc.com Precedence: bulk CORRECTION to Bill deCarle's address: re-COHERENT Internet site: ietc.ca/home/bill/spbill.htm then landline BBS E-Mail: bill@ietc.ca tnx de Dave - AA1A >From owner-laser Thu Mar 13 10:00:37 1997 Return-Path: Received: by berlioz.nsc.com (4.1/SMI-4.1) id AA28052; Thu, 13 Mar 97 10:00:37 PST Date: Thu, 13 Mar 1997 09:39:26 -0800 (PST) From: Clifford Buttschardt To: daveaa1a@ssih.com Cc: Jim Moss , laser@berlioz.nsc.com, microwaveeast@wa1mba.org, sbill@ietc.ca/home/sbill.htm Subject: Re: CCW In-Reply-To: <199703131329.IAA08133@ssih.com> Message-Id: Mime-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: owner-laser@berlioz.nsc.com Precedence: bulk Hi Dave, Jim and the group. All good information provided by AA1A. We meet each night at 0400 UTC on 3591.000 Khz and use MS25 pulse length. If you download and use version 6.0, that program will default to MS25 and BPSK. When signals become difficult, then we invoke ET, which is accomplished by hitting ESC, ET and then SYNC once again. When you see a series of right hand curly brackets or clear text, you have accomplish sync. If you are printing a roundtable, after each "over" hit END and the program automatically resync's on the newer station. We have tried forty meters and 10141.000 KHz as well with sucess. Selective fading is a major pain but we remain on 80 meters to compare notes. The calls to be printed are: VE2IQ, K0LR, WB6RIJ and K7RR Now back to microwaves as 80 meters is really just a subcarrier! Cliff On Thu, 13 Mar 1997 daveaa1a@ssih.com wrote: > > >Tell us more about CCW (Coherent CW)? or the VE2IQ Coherent (BPSK). > > Hi Jim, > > I just spent the LOWFER (160-190khz) season working NO-ONE on CCW and BPSK but am not > giving up. Twelve years ago, random QSO's were common on that band and we did RTTY > and other digital modes... > > To keep a real good idea alive I decided to move the VE2IQ bpsk/ccw scheme up to > HF-VHF and Laser and see if anyone wants to play there. I cannot get my brick > to stay within 10hz at 10ghz so will try later on that.(building PLL).. > > A visit to VE2IQ, Bill deCarle's internet spot ( www.ietc.ca/home/sbill.htm ) and > selecting 'Landline BBS' will make several neat programs available for the downloading. > > FFT.ZIP is a audio spectrum DOS pgm. for the PC > > COHERENT.ZIP is the latest BPSK data program for the PC with 3 split screen panels > and full duplex operation. The older version (included) still has the CCW terminal. > > UTILITY.ZIP is a zero beat utility that lets you determine carier frequency to > within 1 hz. VERY impressive for frequency measurements and setting your transceiver > to the right spot. > > Bill sells a dandy kit that demodulates audio into RS232. It's a BARGAIN.. > I took a serial A/B switch, removed the 'B' connector, installed Bill's pc board > within and replaced the 'B' connector with RCA jacks, now have NORMAL SERIAL or > COHERENT using the same port on the PC. > > There are other neat programs there to download and try such as a Beacon Keyer etc.. > > I hear that the above can be found on HF 160 or 80 but haven't found where as yet. > > Happy Experimenting.. 73 de Dave Riley - AA1A - Marshfield, Mass... > > > > > > > > > > >From owner-laser Thu Mar 13 12:57:40 1997 Return-Path: Received: by berlioz.nsc.com (4.1/SMI-4.1) id AA05870; Thu, 13 Mar 97 12:57:40 PST Date: Thu, 13 Mar 97 20:29:02 UT From: "John Yurek" Message-Id: To: "Laser Messages" Subject: For Sale: New Laser Pointer Pens ! Sender: owner-laser@berlioz.nsc.com Precedence: bulk I thought some of you may be interested in the following: Lyte Electronics Laser Pointer Pen Model # CPP2 <5 mw 670 nm Uses 2 AAA batteries (included) Available from: Damark 1-(800) 827-6767 Quote the following Item # and get FREE SHIPPING! ($5.99 value!) Item # B-50051-509141 Price: $24.99 Non members / $22.49 for Damark Members Remember: Shipping is FREE with the above item number! (Membership is $50 a year which isn't worth it unless you're ordering more than $500 !) I just bought a couple of these and they are brighter than I expected so either the wavelength is higher than specs or the power is higher than expected. However, I don't have any other laser pens to compare them to. Lasing threshold current seems to be approx. 23 to 25 ma. The beam this pen emits is elliptical at close range (several feet) spreading to a more circular pattern at longer distances (several hundred feet) with some noticeable fringe effects around the main beam. Not bad at all considering the price! These pens will work as is for either 800 hz CW or voice/data with a 20 Khz subcarrier. To use higher frequency subcarriers the internal power regulator will have to be redesigned. John K3PGP@msn.com >From owner-laser Thu Mar 13 12:57:39 1997 Return-Path: Received: by berlioz.nsc.com (4.1/SMI-4.1) id AA05859; Thu, 13 Mar 97 12:57:39 PST Date: Thu, 13 Mar 97 20:33:39 UT From: "John Yurek" Message-Id: To: "Laser Messages" Subject: Re: FM Subcarriers on Lasers ! Sender: owner-laser@berlioz.nsc.com Precedence: bulk Jim: I just recently purchased some 670 nm laser pens to play with. Of course one of the first things I tried to do was to use the subcarrier system with them. Since I was playing with an IR laser subcarrier system on the bench when UPS delivered the laser pens, I immediately disconnected the IR laser diode and tried to modulate the pen. The subcarrier was set at 270 khz. Although the subcarrier was definitely there with the 670 nm pen, is was extremely weak. I dropped the subcarrier frequency and didn't notice much difference till I got below about 30 Khz when it started to come up drastically. There was a broad peak around 20 Khz then it started back down again and didn't level off till I got below about 3 Khz. The problem appears to be that the internal power regulator will NOT allow the high frequency signal to get to the diode. The beam looks just as bright as when in the CW mode so it is developing full power but there is very little modulation on the beam. I would estimate that the subcarrier is being attenuated around 60 to 70 db or so. It is detectable but extremely weak which would account for your disappointing results. I took one of the pens apart and found out that they use the typical two transistor feedback power regulator circuit. I have never had much luck modulating these with subcarriers. If you fish around SOMETIMES you can find a frequency that they will work reasonably well with however, they don't display the wide frequency bandwidth that is really needed for good voice, data, and video response. You could get much better range if the internal regulator were redesigned for modulation. If that were done you could use the same system for data, voice and video with about the same range or perhaps even better depending on just how well your present regulator is handling the 800 hz modulation. So It looks like if you want to use the subcarrier method for data/voice/video you will have to come up with a new regulator circuit that will pass the subcarriers! However, you might try modulating the pen with a 50% duty cycle square wave and do a frequency response run. You may find that you can use a relatively low (20 khz or so) subcarrier without modifying the pen at all. I have used 20 Khz nbfm/fsk subcarriers and they work fine for voice and data and it appears that these pens (obtained from Damark) will work just fine as is for voice/data work with a 20 Khz subcarrier. John K3PGP@msn.com >From owner-laser Thu Mar 13 17:43:41 1997 Return-Path: Received: by berlioz.nsc.com (4.1/SMI-4.1) id AA16755; Thu, 13 Mar 97 17:43:41 PST Date: Thu, 13 Mar 1997 17:32:39 -0800 (PST) From: Clifford Buttschardt To: John Yurek Cc: Laser Messages Subject: Re: For Sale: New Laser Pointer Pens ! In-Reply-To: Message-Id: Mime-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: owner-laser@berlioz.nsc.com Precedence: bulk Hi John. Very interesting regarding the Pens from Damark. I guess we all will have to have one to play with although I would have preferred a 650 nM model if it were to come about! Interesting regarding the power regulator circuit. I am not familiar with this but will be when I get one apart. Is it possible to use a very narrow pulse at a rate above 20 KHz improving efficiency and also creating the subcarrier? From what I have been reading on the reflector, subcarriers are not all that useful and if frequencies as low as 20 KHz have to be used, brick wall filters are required to get a reasonably good voice bandwidth through. What do you recommend as a source of PIN diode detectors other than surplus bar code scanners for weak signal work? Cliff Buttschardt K7RR >From owner-laser Thu Mar 13 19:41:33 1997 Return-Path: Received: by berlioz.nsc.com (4.1/SMI-4.1) id AA20518; Thu, 13 Mar 97 19:41:33 PST Date: Fri, 14 Mar 97 01:17:25 UT From: "John Yurek" Message-Id: To: "Laser Messages" Subject: For Sale: New Laser Pointer Pens ! Sender: owner-laser@berlioz.nsc.com Precedence: bulk One further note & a correction on the laser pointer pens from Damark: They have a no questions asked 60 day return policy! So if you the pen isn't as expected, put it back in the box and send it back for a complete refund! Of course this assumes you haven't drilled holes in it and have wires hanging out of it :-^) ! Lyte Optronics Laser Pointer Pen < *** Name wrong in previous post ! *** Model # CPP2 <5 mw 670 nm Uses 2 AAA batteries (included) Available from: Damark 1-(800) 827-6767 Quote the following Item # and get FREE SHIPPING! ($5.99 value!) Item # B-50051-509141 Price: $24.99 Non members / $22.49 for Damark Members Remember: Shipping is FREE with the above item number! John K3PGP@msn.com >From owner-laser Fri Mar 14 01:13:34 1997 Return-Path: Received: by berlioz.nsc.com (4.1/SMI-4.1) id AA00435; Fri, 14 Mar 97 01:13:34 PST Date: Fri, 14 Mar 97 09:08:31 UT From: "John Yurek" Message-Id: To: "Laser Messages" Subject: Re: FM Subcarriers on Lasers ! Sender: owner-laser@berlioz.nsc.com Precedence: bulk Cliff: I am posting this here since this is probably of interest to everyone and may clear up some misunderstandings about the laser subcarrier systems that I am working with. > Very interesting regarding the Pens from Damark. I guess we all > will have to have one to play with although I would have preferred a 650 > nM model if it were to come about! >From what I've seen you're better off with the 670 nm model assuming your purpose in buying one is for communications use and not simply to look at! The 670 nm pens develop more power and the lower frequency seems to work better with most solid state detectors other than PMTs. Most PMTs seem to peak higher in frequency. The one I have is noticeably more sensitive to green! (Ugh!) > From what I have been reading on the reflector, subcarriers are not all that useful and if frequencies as low as 20 KHz have to be used, brick wall filters are required to get a reasonably good voice bandwidth through. What are you basing this on??? My experiences are 100% opposite on both the usefulness of subcarriers and the reference to brick wall filters! That's why I've been making so much noise on here lately about subcarrier systems. Many people on here are missing a really good thing! You need to re-read my previous posts! Unfortunately most hams don't have a whole lot of experience with subcarrier systems. Technically they are only legal on the 900 Mhz band so I can understand why. (This could have changed since I checked many years ago when we got the 900 Mhz band.) I've been working with subcarrier systems now for over 30 years both commercially and with ham radio. I first got involved with subcarrier systems with commercial FM broadcasting and later on working with microwave relay links. Many of the microwave links that I work with actually use subcarriers quite a bit lower than 20 khz for voice circuits! Many systems put 5 Khz voice quality circuits subcarriers as low as 10 khz! Some subcarriers are NBFM and others are SSB! You can carry some pretty decent audio on a 20 Khz subcarrier. It will beat any two meter nbfm audio channel for frequency response any day! You will NOT need any filtering at all if you are using a VLF converter into a communications receiver. Just take what is normally the audio output of the optical detector and dump it into the VLF converter. Just make sure you don't overload the converter. Some optical front ends have enough gain to put out several volts of signal! If you want a stand alone receiver you can make a pretty decent one using a single stage op-amp filter feeding a CD4046 PLL demodulator. Just remember NOT to make the filter too narrow or you will chop off the sidebands! That is why I suggest a SINGLE stage filter. For nbfm you want a humped response rather than a flat response, something that many people miss. I suggested this system to a friend and he decided to improve on my design by using TWO stages of filtering. His system produced very good quieting with weak signals but the audio sounded AWFUL because the bandwidth was TOO narrow. He ended up pulling one op-amp out and putting a jumper wire across the socket to make it work! The PLL system will work quite well but I think the VLF converter/communications receiver system will pull a signal out of the noise that the PLL can't touch. Fortunately most laser links seem to produce ridiculously strong signals even over great distances! I have had absolutely no problem at all with voice and data on 20 khz subcarriers. In fact the only reason you might want to go higher would be to put more than one data channel on the system or to use video simultaneously. A rule of thumb seems to be that the subcarrier should be AT LEAST twice the highest modulation frequency. (There are ways around this but this isn't the place nor the time!) With a 20 Khz subcarrier you should have no problem setting up an audio circuit that is flat out to at least 10 Khz! This is also why you have to go to something like a 10 Mhz subcarrier to carry video! And you don't need any fancy filters to make any of this work! This is NOT theory on my part. I am basing this on actual working systems that I am using! For a 5 Khz voice quality channel there is absolutely no reason why you couldn't use a 10 khz subcarrier! (I think I smell a construction article brewing!) Perhaps your reference to brick wall filters was in filtering the audio from the 20 khz subcarrier. The 20 khz subcarrier never makes it through the demodulator. If it's working correctly you feed the 20 khz subcarrier in one end and baseband audio comes out the other! Same idea with balanced modulators and demodulators used with SSB. The carrier ends up suppressed. I've only had the pens less than 24 hours but I have determined that there isn't some magic line where they quit at exactly 20 khz! At 40 khz they are only down about 3 db or so and I'm not sure at this point if that 3 db is the receiver or the transmitter. At 67 khz things really start to fall apart. I do know for a fact that the pen will NOT pass 270 Khz which the home-brew laser diode transmitter worked just fine with. In fact the home-brew laser diode system works just fine with a 10 Mhz subcarrier modulated with NTSC color video along with voice and data subcarriers simultaneously! I'm sorry I can't offer much on optical detectors. I am using unknown junk box diode and phototransistor detectors for most of my experiments. Other than the optical biasing, nothing unusual here. With the IR system I couldn't make the optical biasing work until I woke up and replaced the red LED with an IR LED and then the optical biasing worked with the IR system as well. I still don't know why this works so well. I have never seen any reference to optical biasing anywhere. The most sensitive detectors to date though have been the PMTs (Photo Multiplier Tubes). However, since they can be damaged with excessive light I'm afraid to use the one I have other than at night! Even with a red filter on it I think sunlight is more than it can safely handle. Since no one seems to be able to come up with a source for these I have decided to leave mine in a box (protected from light) in the filing cabinet until I really need it! After one brief exposure to bright light it takes days for the PMT noise floor to drop back to normal. John K3PGP@msn.com >From owner-laser Fri Mar 14 06:15:24 1997 Return-Path: Received: by berlioz.nsc.com (4.1/SMI-4.1) id AA02894; Fri, 14 Mar 97 06:15:24 PST From: sjnoll@ix.netcom.com Date: Fri, 14 Mar 1997 08:10:19 -0600 (CST) Message-Id: <199703141410.IAA27802@dfw-ix16.ix.netcom.com> Mime-Version: 1.0 Content-Type: text/plain Content-Transfer-Encoding: 7bit Subject: High Current Pulsing of LEDs To: laser@berlioz.nsc.com X-Mailer: SPRY Mail Version: 04.10.06.22 Sender: owner-laser@berlioz.nsc.com Precedence: bulk I looked through some LED manufacturer data books at work yesterday to see what they said about pulsing LEDs for more output. American Bright - for their 50mA CW DC (max) IR LEDs they have a 1 amp pulse spec for 10 uSec wide pulses, 1% duty. Gilway has the same spec for theirs, except 1.2 amps. Toshiba - for their 100 mA IR LEDs has a 1 amp spec for widths of 100 uSec and less, 1% duty. Opto Diode makes especially high power IR LEDs. They can generally be pulsed at 3 amps, 10 uSec, 400 Hz. I have heard a rule of thumb of doubling the current and quartering the duty when going from the CW DC current rating. 73, Steve J. Noll | Ventura CA | WA6EJO | sjnoll@ix.netcom.com | http://www.netcom.com/~sjnoll/usedequip.html | http://www.netcom.com/~sjnoll/peltier.html >From owner-laser Fri Mar 14 07:35:20 1997 Return-Path: Received: by berlioz.nsc.com (4.1/SMI-4.1) id AA05414; Fri, 14 Mar 97 07:35:20 PST Date: Fri, 14 Mar 97 15:22:43 UT From: "John Yurek" Message-Id: To: "Laser Messages" Subject: mouse tech talk? Sender: owner-laser@berlioz.nsc.com Precedence: bulk >Any technical info about the mouse and how it operates would be appreciated. > >GL...Art, KY1K. Sorry for the delay. I forgot to reply to this with all the excitement over subcarrier systems! >From my experience most computer mice that plug into the serial port run at 2400 baud and produce a 'normal' serial bit stream. You should be able to load up most any serial communication program (I used Telix) and set it to 2400,n,8,1 and when you move the mouse around you should see the data being sent. This may NOT work from within Windows since Windows itself pretty much takes over control of the bit stream coming from the mouse, so I suggest you do it from DOS. You do NOT need to initialize the mouse or load any drivers for this test! Back in the Turbo Pascal days I used to write many DOS programs that used a mouse as an input device. If you can find an old copy of Turbo Pascal for DOS you should find more info than you probably need about how to talk to the mouse. (First call in a mouse translator. If communications break down you need a consular. If that doesn't work call the mouse psychiatrist! :-^) If you're really serious about this I'll dig through my collection of old software and see if I can find some source code. I've run a public BBS system now for 15 years and have managed to collect something like 15 gb so it may take a while! John K3PGP@msn.com >From owner-laser Fri Mar 14 09:21:00 1997 Return-Path: Received: by berlioz.nsc.com (4.1/SMI-4.1) id AA08762; Fri, 14 Mar 97 09:21:00 PST From: daveaa1a@ssih.com Date: Fri, 14 Mar 1997 12:00:45 -0500 Message-Id: <199703141700.MAA11957@ssih.com> Mime-Version: 1.0 Content-Type: text/plain Content-Transfer-Encoding: 7bit Subject: Hacking Today To: laser@berlioz.nsc.com X-Mailer: SPRY Mail Version: 04.00.06.17 Sender: owner-laser@berlioz.nsc.com Precedence: bulk Gudday Light Bugs.. Well there sure seems to be a surge in interest on light comms.. Steve Knoll's rig with the pin/op-amp/filter chip still continues to be best baseband/portable/sensitive here.. It looks out the window, up the street and sees the difference in NOISEY head and tail lights.. It tells me when its raining and when there is discharge in the sky..Even hears aircraft strobes way out past where i quit seeing them..a most excellent set-up.. Should do real DX.. Of course DSP and audio filters etc can help and a nice Celestron is a real good dish antenna..The best components i can find for the above and would like to be updated if it's not a secret are: Photo Diode EG&G Vactec VTP1188s from Newark p/n 95f9029 Low noise op-amp that really beats a 741 is LT1055cnb from Digikey Bandpass filter to keep only audio frequencies is TOKO THB111A from Digikey A 4" lense from Edmunds Scientific in some PVC is light, portable, self contained and is a keeper here.. Oh, a 4x rifle scope mounted on above takes the pain off aiming and is sure every time.. This all goes on a tripod mount.. As far as transmit goes, I replaced the 870nm diode from the TIMELINE diode offer in Nuts and Volts with a brighter 650nm one, only to learn aiming, now can revert to IR diode which is more power and i understand propagates better in air. I mounted the diode and collimator on a 4x rifle scope in turn mounted these on a micrometer controlled X/Y table,, thence to a 1/4" nut for mounting on good tripod or rock wall etc..The modulator is just a npn and mic. driver with a 555 square wave at 1000 hz makes plenty of audio noise+ way up to 500 khz.. This way i get A1-A2-A3 ops in 1 little box.. The very dirty square wave makes a spectrum way out past 500 khz.. with a blip every 1 khz.. ====================================================================================== Subcarriers: I never thought I would dedicate a real comm. receiver to collecting light but you really need to if your gonna get real into this..My leftover Burhans VLF kit converter and the ts930 let me tune baseband out to wherever the photo diode stops receiving.. Mine seems to quit at a mhz or so..If you are going to transfer data and have a 'QUIET' link with good S/N think of all the voice and data circuits you can have at once not to mention the analog/digital remote control. Getting the entire HF band to repeat many times in one domain is now making use of spectrum, and you just don't QRM anybody.. A 3mw diode in a 18" mirrored microwave type dish is plenty good for local hops..no need for colimator..I picked 67khz cuz there are SCA receivers left over from the commercial FM band but if you have a full communications receiver then you can tune to ANY sub-carrier..Even baseband is useable by notching the carrier caused by the L.O. in my case 4 mhz, so a 1 kc. audio received in CW mode with filtering is at least -65db noise from local signals.. There is a module at radio shack and it is a real good starter sub system.. p/n 276-137 contains the IR receiver, limiter, band pass filter, demodulator, integrator and comparator all in a nice tin box for $3.49.. A Celestron or good lense can have this thing seeing way across the valley.. Oh it's 40khz c.f. is 4khz wide and needs light from 880 to 1080nm.. 6volt supply..It's a tv remote control sensor...Just beef up the clicker, get off your couch, and go to work.. why not keep the same keyboard sigs as the clicker and add voice/data channel.. I am in search of a better receiving diode as far as bandwidth goes..??.. Well if this windbag spam doesn't clog the system, i'll try another some time.. de Dave Riley - AA1A - QRV/QRU from FN42/41/51.. Radio Free Marshfield..(Fessenden) >From owner-laser Fri Mar 14 09:43:21 1997 Return-Path: Received: by berlioz.nsc.com (4.1/SMI-4.1) id AA09669; Fri, 14 Mar 97 09:43:21 PST Date: Fri, 14 Mar 97 09:43:18 PST From: jmoss (Jim Moss) Message-Id: <9703141743.AA09663@berlioz.nsc.com> To: laser Subject: duty cycle and power Sender: owner-laser@berlioz.nsc.com Precedence: bulk Steve and others, When we are looking at "power" and duty cycle, The actual signal power is Duty Cycle * Peak Power I'm thinking of digital modulation techniques, and saying that the overall signal to noise isn't directly related to the peak power. Boy, I did a lousy job of explaining that. I need my reference notes that are at home! Eb/N0 Jim WB9AJZ/6 >From owner-laser Fri Mar 14 11:55:30 1997 Return-Path: Received: by berlioz.nsc.com (4.1/SMI-4.1) id AA14172; Fri, 14 Mar 97 11:55:30 PST Date: Fri, 14 Mar 1997 11:42:42 -0800 (PST) From: Clifford Buttschardt To: sjnoll@ix.netcom.com Cc: laser@berlioz.nsc.com Subject: Re: High Current Pulsing of LEDs In-Reply-To: <199703141410.IAA27802@dfw-ix16.ix.netcom.com> Message-Id: Mime-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: owner-laser@berlioz.nsc.com Precedence: bulk Hi Steve and the net. Good information! I think doubling the average current and quartering the duty cycle is a good start. Just this morning I FINALLY found the notes taken at a seminar put on by Santa Barbara research regarding their optical communicator. They used a GaAs source at 9040A putting out ten watts peak. The pulse duration was 100 nSecs and a divergance of three degrees. The subcarrier frequency was SIX kilohertz rather than thirty which course, requires a very good brick wall filter at three kilohertz. That was a tough job then but I would suppose a DSP filter nowdays would be far easier. The optical gain was 5X on each end. The claim was four miles lines of sight for voice communication. Steve, you might remember my asking about some Hamamatsu Head-on photomultiplier tubes that I obtained from a junked CAT scan machine. With the optical communicator mentioned above, I found those data sheets. Can you remember to whom these tubes were given? I think one fellow now lives in Bend, OR--KI7WB and I will contact him. In my usual confusion, I think I still have a couple around here. 73 all Cliff Buttschardt K7RR On Fri, 14 Mar 1997 sjnoll@ix.netcom.com wrote: > > I looked through some LED manufacturer data books at work yesterday to > see what they said about pulsing LEDs for more output. > > American Bright - for their 50mA CW DC (max) IR LEDs they have a 1 amp > pulse spec for 10 uSec wide pulses, 1% duty. > > Gilway has the same spec for theirs, except 1.2 amps. > > Toshiba - for their 100 mA IR LEDs has a 1 amp spec for widths of 100 > uSec and less, 1% duty. > > Opto Diode makes especially high power IR LEDs. They can generally be > pulsed at 3 amps, 10 uSec, 400 Hz. > > I have heard a rule of thumb of doubling the current and quartering the > duty when going from the CW DC current rating. > > 73, > > Steve J. Noll | Ventura CA | WA6EJO | sjnoll@ix.netcom.com > | http://www.netcom.com/~sjnoll/usedequip.html > | http://www.netcom.com/~sjnoll/peltier.html > >From owner-laser Fri Mar 14 11:58:12 1997 Return-Path: Received: by berlioz.nsc.com (4.1/SMI-4.1) id AA14247; Fri, 14 Mar 97 11:58:12 PST Message-Id: <199703141952.OAA19231@host-04.colby.edu> X-Sender: aballen@colby.edu X-Mailer: Windows Eudora Light Version 1.5.2 Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Date: Fri, 14 Mar 1997 14:52:33 -0500 To: laser@berlioz.nsc.com From: "Art Allen, KY1K" Subject: FM/subcarriers? Sender: owner-laser@berlioz.nsc.com Precedence: bulk Hi Everyone, I've been following the recent discussion. It's very interesting, but I'm wondering IF we have lost track of the basic 'more bandwidth=reduced signal to noise ratio' concept. The 'reduced signal to noise ratio' means LESS RANGE for a given TX power. Certainly, we can transmit more info with a wider bandwidth, this is basic physics and I understand that. I'm looking for VUCC, which means 5 grids. Up here in the north, our grids are a little smaller...but, still, its a pretty tall order and I'm wondering if we really have the extra signal to noise ratio to spare over such long distances? --------------------------- Now, if we sucessfully modulate a laser with a very very very tight beam (less than .1 millirad), then we can actually UTILIZE the increased data rates to MINIMIZE the time that the laser actually has to be aimed at the target. With such a high bandwidth TX/RX system, it might be possible to exchange the 30 or so binary bits we need for a QSO is a few tens of milliseconds (or less). In PRACTICAL terms, this means that we can use laser tx/high power spotting scope mounted on a rifle and just sweep across the target area till the other end hears a blip (hand held aiming). If the other side can decode that blip, and extract 30 bits-then that's half the QSO (almost). High speed meteor scatter guys have been doing this for years in Europe. ---------------------------- I am following this recent thread involving modulation of the laser pens by various means. It's interesting and I thank all who contribute and obviously this type of research and and interaction MUST continue... BUT, for sheer DX capability and VUCC grid chasing, I'm banking on a simple 10 HZ bandwidth system that just detects the presence of the unmodulated laser beam itself. ---------------------------- GL and good dx Art, KY1K. >From owner-laser Sat Mar 15 02:35:25 1997 Return-Path: Received: by berlioz.nsc.com (4.1/SMI-4.1) id AA12610; Sat, 15 Mar 97 02:35:25 PST Date: Sat, 15 Mar 97 09:22:03 UT From: "John Yurek" Message-Id: To: "Laser Messages" Subject: FM Subcarriers on Lasers & Pulsed Systems! Sender: owner-laser@berlioz.nsc.com Precedence: bulk Cliff: >The pulse duration was 100 nSecs and a >divergance of three degrees. The subcarrier frequency was SIX kilohertz >rather than thirty which course, requires a very good brick wall filter at >three kilohertz. I don't think we are talking about exactly the same thing here! Although I am not familiar with the above it seems from your description that this is NOT an FM system! For a quick test I backed the subcarrier down to 6 khz and had absolutely no problem at all putting a 3 khz nbfm voice channel on the system WITHOUT any fancy filters! I am using a 50% duty cycle square wave in all cases and not anything like the 100 nsec mentioned above. For the 6 Khz test I was running the output of the optical detector into my favorite double balanced mixer upconverter (fancy name for a VLF converter with NO RF stage!) into an NBFM communications receiver. Granted most communications receivers have pretty good IF filters in them so I also tried the PLL system with good results! The PLL systems consisted of a CD4046 demodulator. However, the single stage op-amp filter in front of it was designed for 20 Khz and I pulled it down to 6 Khz by increasing the resistors in the feedback loop so it wasn't optimum but it worked just fine. I might ad that the system will work without this filter by simply dumping the output from the optical front end into the PLL but I don't really like to run it like that. Most PLL systems work better with a small humped response filter in front of them. I think you need to sit down and build up an fm subcarrier system and play with it. You'll learn more in one evening than I can tell you here in a week! The nbfm subcarrier system is so ridiculously simple and works so well that I'm surprised no one else is playing with them! The pulse systems like you described using 100 ns pulses are a different breed of animal and I can understand why you would need something special in the way of filtering! John K3PGP@msn.com >From owner-laser Sat Mar 15 02:35:18 1997 Return-Path: Received: by berlioz.nsc.com (4.1/SMI-4.1) id AA12592; Sat, 15 Mar 97 02:35:18 PST Date: Sat, 15 Mar 97 09:11:34 UT From: "John Yurek" Message-Id: To: "Laser Messages" Subject: FM Subcarriers on Lasers & Bandwidth ! Sender: owner-laser@berlioz.nsc.com Precedence: bulk Art: > I've been following the recent discussion. It's very interesting, but I'm > wondering IF we have lost track of the basic 'more bandwidth=reduced signal >to noise ratio' concept. Very good point and one that I haven't overlooked! >From what I have been able to gather most stations using the 800 hz cw method are NOT using any filters at all on the audio system meaning these are WIDEBAND modulated CW systems and shouldn't be confused with the typical narrowband cw RF systems that we all are familiar with. It has been my experience that a 20 khz nbfm system with a 10 khz bandwidth will outperform the wideband 800 modulated cw systems any day since the voice system actually has a narrower bandwidth! Of course if one were to apply some type of narrow band filtering system or coherent detection scheme to the 800 cw system then of course it would leave the voice system in a trail of dust! However, most stations don't seem to be doing anything fancy in the way of filtering on the cw systems since the paths we all have to work with usually produce extremely strong signals and don't require it. So far though I haven't been able to find a direct path long enough to really challenge either system. The most challenging paths to date have all been bounced paths (bouncing off some object visible to both stations) and on these paths the 20 khz subcarrier system with a 10 khz passband has produced higher signal to noise ratios than an unfiltered 800 hz cw system! John K3PGP@msn.com >From owner-laser Sat Mar 15 02:35:20 1997 Return-Path: Received: by berlioz.nsc.com (4.1/SMI-4.1) id AA12598; Sat, 15 Mar 97 02:35:20 PST Date: Sat, 15 Mar 97 09:21:33 UT From: "John Yurek" Message-Id: To: "Laser Messages" Subject: Ruby Rod Amplifier ! Sender: owner-laser@berlioz.nsc.com Precedence: bulk Does anyone have any experience with very high power Ruby Rod systems? I managed to come by some high power ruby rods a while back and have been experimenting with them. Unfortunately these do NOT have mirrors plated on the ends as they were used in amplifier service. Typically they used a smaller ruby rod as an oscillator (a small ruby rod with mirrors plated on the ends) which was then fired into the larger rod which had no mirrors and worked as an amplifier. When used in this mode the rod produced amplification over an extremely narrow range of optical frequencies centered on the ruby emission wavelength of 694.3 NM. It is pumped with an array of xenon lamps around the rod similar to what is done with the oscillator. The problem is I don't have a ruby rod oscillator! With that in mind has anyone ever seen a system using a xenon lamp in place of the smaller ruby rod oscillator? (Not to be confused with the xenon pump lamps!) I'm sure this reduces the already lousy efficiency but I have already had some success in doing this. It appears that you have to fire the xenon pump lamps first then fire the oscillator (in this case the xenon lamp used as an exciter) because the rod only works as an amplifier for a brief instant AFTER the pump lamps are fired and the energy levels fall back to normal. What I am trying to avoid here is coming up with a ruby rod that has plated mirrors on it to allow it to oscillate! (Anyone have one of these in their junk box?) Does anyone know if it's possible to use external mirrors to make an oscillator? Anyone know how much gain I can get out of a given length ruby rod? This would be helpful in determining the amount of power the exciter needs to put out. I would consider converter over to a Nd-Yag 1064nm system but so far haven't seen a reasonably priced Nd-Yag! Also, I just hate to see these ruby rods gathering dust! John K3PGP@msn.com >From owner-laser Sat Mar 15 02:35:23 1997 Return-Path: Received: by berlioz.nsc.com (4.1/SMI-4.1) id AA12604; Sat, 15 Mar 97 02:35:23 PST Date: Sat, 15 Mar 97 08:58:56 UT From: "John Yurek" Message-Id: To: "Laser Messages" Subject: Duty Cycle and Power Sender: owner-laser@berlioz.nsc.com Precedence: bulk Cliff: > Is it possible to use a very narrow pulse at a rate above 20 KHz improving > efficiency and also creating the subcarrier? I have tried short duty cycle pulsing of junk box type IR LEDs (and Radio Shack IR LEDs !) and have had no problem pulsing them at currents in the 2 to 4 amp region provided that I kept the duty cycle extremely low, something like 100 nsec pulses and very low rep rates, like 400 hz or so. The only problem with this is that as you start raising the carrier frequency the duty cycle goes up. By the time you get to something like 20 khz the duty cycle gets pretty high and the diode starts to heat and if you push it enough you no longer have a diode! The reason I didn't answer this right away is because I thought we were talking about LASER diodes NOT LEDs (???) and on that one I have a question myself! Just how much can a LASER diode take? I know from playing with them that there is an extremely small range between the threshold current, typical operating current and the point where the diode goes into a self destruction mode! I am of the opinion that most of the problem here is heat. If this is so one would think that you could pulse a laser diode much the same as you could a typical LED. However, I have never seen a this done with a laser diode. What will happen if you try to pulse a typical laser diode with something like a 100 nsec 1 amp pulse at a 400 hz rep rate? Will it behave much the same a regular LED or will it immediately go into a self destruct mode? Or will it simply refuse to lase and just behave as a bright LED? I'd give this a try but since laser diodes aren't as cheap as regular LEDs I don't want to push my luck! On the subject of pulsed laser systems, does anyone know if the avalanche type IR laser diodes are still available. These typically were used with a 100 to 400 volt DC power supply, ran with extremely short duty cycle pulses at low rep rates, and put out power levels measured in WATTS! I have been looking for a couple of these for some experiments and have asked on here a couple of times before with no response. Perhaps with all the new people on here maybe someone has a couple in their junk box or can tell me where I can buy a couple at a reasonable price! PS - I am well aware of the dangers in working with high power IR systems so I don't need Email telling me how dangerous they are... Thanks in advance! John K3PGP@msn.com >From owner-laser Sat Mar 15 07:33:23 1997 Return-Path: Received: by berlioz.nsc.com (4.1/SMI-4.1) id AA17730; Sat, 15 Mar 97 07:33:23 PST From: sjnoll@ix.netcom.com Date: Sat, 15 Mar 1997 09:32:40 -0600 (CST) Message-Id: <199703151532.JAA06042@dfw-ix10.ix.netcom.com> Mime-Version: 1.0 Content-Type: text/plain Content-Transfer-Encoding: 7bit Subject: Mice To: laser@berlioz.nsc.com X-Mailer: SPRY Mail Version: 04.10.06.22 Sender: owner-laser@berlioz.nsc.com Precedence: bulk Some worthless comments abt computer mice... Where I work (Advanced Photonix) we make detectors for use in computer mice. I think for Mouse Systems, maybe others. These are four element photodiodes packaged in a clear plastic molded case like a 8-pin DIP, but with only four pins out of one side. I don't know how they are used by the customer(s). Sounds like a quadrature encoder wheel system, but that's just a guess - maybe that's too elaborate for a mouse. RE: writing software for mice... I remember writing a neat FORTH program that used a mouse. I thought it was funny that the mouse driver used parameters like "SET-MICKEYS". Someone had a sense of humor! 73, Steve J. Noll | Ventura CA | WA6EJO | sjnoll@ix.netcom.com | http://www.netcom.com/~sjnoll/usedequip.html | http://www.netcom.com/~sjnoll/peltier.html >From owner-laser Sat Mar 15 07:52:28 1997 Return-Path: Received: by berlioz.nsc.com (4.1/SMI-4.1) id AA17913; Sat, 15 Mar 97 07:52:28 PST From: sjnoll@ix.netcom.com Date: Sat, 15 Mar 1997 09:47:49 -0600 (CST) Message-Id: <199703151547.JAA12516@dfw-ix7.ix.netcom.com> Mime-Version: 1.0 Content-Type: text/plain Content-Transfer-Encoding: 7bit Subject: Pulsing LEDs To: laser@berlioz.nsc.com X-Mailer: SPRY Mail Version: 04.10.06.22 Sender: owner-laser@berlioz.nsc.com Precedence: bulk Some more thoughts on how hard you can hit a LED... We might get in trouble if we apply pulse rules for the special high power LEDs such as those made by Opto Diode to garden-variety LEDs we come across. The high power guys might be designed different, might have more heat sinking, etc. Also, there might be a different 'rule-of-thumb' for IR and Vis LEDs due to different materials used? Maybe one could sacrifice a LED or two in experiments to see how much a particular model could take... Set up a test fixture to hold a LED and detector firmly - so you get repeatable measurements - and make sure the detector is not saturated. Pulse the LED at some current & pulse width & rep rate. Measure the detector output when you start the test, and again after 24 hours of continuous running. If the LED output hasn't dropped by more than X% after this period then increase the current, etc., and go for another 24 hours... 73, Steve J. Noll | Ventura CA | WA6EJO | sjnoll@ix.netcom.com | http://www.netcom.com/~sjnoll/usedequip.html | http://www.netcom.com/~sjnoll/peltier.html >From owner-laser Sat Mar 15 08:54:17 1997 Return-Path: Received: by berlioz.nsc.com (4.1/SMI-4.1) id AA18643; Sat, 15 Mar 97 08:54:17 PST Date: Sat, 15 Mar 1997 08:47:13 -0800 (PST) From: Clifford Buttschardt To: John Yurek Cc: Laser Messages Subject: Re: For Sale: New Laser Pointer Pens ! In-Reply-To: Message-Id: Mime-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: owner-laser@berlioz.nsc.com Precedence: bulk Hi All. John is right about the pointer pens! They are still available for this price but you MUST use this order number. I got a new catalog just yesterday in which shipping was not included (and more expensive!). Cliff Buttschardt K7RR ex W6HDO On Thu, 13 Mar 1997, John Yurek wrote: > I thought some of you may be interested in the following: > > Lyte Electronics Laser Pointer Pen > Model # CPP2 > <5 mw 670 nm > Uses 2 AAA batteries (included) > > Available from: Damark 1-(800) 827-6767 > > Quote the following Item # and get FREE SHIPPING! ($5.99 value!) > > Item # B-50051-509141 > > Price: $24.99 Non members / $22.49 for Damark Members > > Remember: Shipping is FREE with the above item number! > > (Membership is $50 a year which isn't worth it unless you're ordering more > than $500 !) > > I just bought a couple of these and they are brighter than I expected so > either the wavelength is higher than specs or the power is higher than > expected. However, I don't have any other laser pens to compare them to. > > Lasing threshold current seems to be approx. 23 to 25 ma. The beam this pen > emits is elliptical at close range (several feet) spreading to a more circular > pattern at longer distances (several hundred feet) with some noticeable fringe > effects around the main beam. Not bad at all considering the price! > > These pens will work as is for either 800 hz CW or voice/data with a 20 Khz > subcarrier. To use higher frequency subcarriers the internal power regulator > will have to be redesigned. > > John > K3PGP@msn.com > >From owner-laser Sat Mar 15 11:19:26 1997 Return-Path: Received: by berlioz.nsc.com (4.1/SMI-4.1) id AA20168; Sat, 15 Mar 97 11:19:26 PST From: Wb9ajz@aol.com Date: Sat, 15 Mar 1997 14:16:26 -0500 (EST) Message-Id: <970315141625_1715007205@emout01.mail.aol.com> To: laser@berlioz.nsc.com Subject: Mirrors and Lens Gain Experiment Sender: owner-laser@berlioz.nsc.com Precedence: bulk Did some experiments last night: Size/Type Area Measured Gain Area Gain delta in2 dB dB dB .25x.25 sensor 0.0625 0 0 0 power meter 2.125" round concave mirror 3.55 22dB 17.5dB 4.5dB 2.25" round plastic lens 3.98 22.7 18 4.7 8.5" "FIXED" round mirror 56.75 36 29.6 6.4 8.5" round mirror 56.75 39 29.6 9.4 8x10.5" fresnel book mag 84 38 31.3 6.7 Kevin (N5XSA) will know what "FIXED" means! I had an accident with his mirror. Tripods do fall over! If you plot these on log linear format, you will see the gains are almost straight line with area. I don't know quite why the actual measured values were > than the calced area ones. I used a pen light at 8", and measured light strength into the meter, then placed either a mirror or a lens at the point were the meter sensor was, and moved the meter to where the focal point was. Some of the mirrors did not form a clean dot, so some energy was lost outside the sensor. One of the findings I think is evident, is that the fresnel lens has some loss over theoretical. You can see that a 8.5" mirror is better than the 8x10.5" fresnel, even though the area is greater. The 8.5" mirror appear to be intended as "makeup" mirrors. The 8x10.5" fresnel is a book page magnifier. ($7 at most book stores!) Jim WB9AJZ/6 >From owner-laser Sat Mar 15 16:56:00 1997 Return-Path: Received: by berlioz.nsc.com (4.1/SMI-4.1) id AA23954; Sat, 15 Mar 97 16:56:00 PST Date: Sun, 16 Mar 97 00:51:32 UT From: "John Yurek" Message-Id: To: "Laser Messages" Subject: Mirrors and Lens Gain Experiment Sender: owner-laser@berlioz.nsc.com Precedence: bulk Jim: > I used a pen light at 8", and measured light strength into the meter, then > placed either a mirror or a lens at the point were the meter sensor was, > and moved the meter to where the focal point Please excuse my dumb questions but I seem to be missing something here! Could you elaborate on this just a bit??? If the light pen was only 8 inches away wouldn't it only make a small dot in the center of the mirror or lens and NOT make use of the full diameter? I don't see how you can develop full gain out of the mirror or lens like this. In order to use the full aperture of the lens or mirror you have to first spread the beam of the laser to the diameter of the lens or mirror in question. What I am missing here? In my experiments I normally use a small lens directly in front of the laser which spreads the beam. The final lens or mirror is then placed in front of this and the distance varied between the two lens until focus is achieved. The only tricky part is choosing the first lens so that the beam is spread to exactly the diameter of the final lens when the distance between the two lens is such that the system is in focus. (Did I say that???) If it's too big you spill energy over the edge and if it's too small you waste the outer area of the lens or mirror. Your gain figure seem a LOT lower than what I am seeing. Could this be because you aren't using the full diameter of the lens or mirrors. (???) This is the same problem you end up with in designing feed systems for microwave dishes. You want the beam width from the feed horn to just illuminate the entire surface of the dish without spilling over the edges. In this case you need to spread the diameter of the laser beam to the diameter of the final lens or mirror. Probably the best way to check gain figures would be with a test signal several miles away and use the lens/mirrors on the receiver. John K3PGP@msn.com >From owner-laser Sun Mar 16 00:17:00 1997 Return-Path: Received: by berlioz.nsc.com (4.1/SMI-4.1) id AA28754; Sun, 16 Mar 97 00:17:00 PST Date: Sun, 16 Mar 97 08:13:28 UT From: "John Yurek" Message-Id: To: "Laser Messages" Subject: CCW Sender: owner-laser@berlioz.nsc.com Precedence: bulk To ALL: How much signal to noise improvement can be had with CCW and with the Sigma Delta board mentioned in the VE2IQ files? I have been experimenting with indirect paths by bouncing laser signals off of a common object that two stations can both see. Some of these paths can be quite challenging. If the signal is in the noise can CCW or BPSK make it into something useable? I've heard people talk about being able to read a signal that's 30 db BELOW the noise! Although I've been able to demonstrate this on the bench, CCW never worked this well on the air with difficult paths on HF, EME and VHF tropo. Most of the difficulty seemed to be establishing a coherent reference to drive the demodulator. Since I haven't done anything along these lines for years I was wondering how well these newer techniques work. John K3PGP@msn.com >From owner-laser Sun Mar 16 06:43:16 1997 Return-Path: Received: by berlioz.nsc.com (4.1/SMI-4.1) id AA04204; Sun, 16 Mar 97 06:43:16 PST From: sjnoll@ix.netcom.com Date: Sun, 16 Mar 1997 08:38:57 -0600 (CST) Message-Id: <199703161438.IAA22096@dfw-ix5.ix.netcom.com> Mime-Version: 1.0 Content-Type: text/plain Content-Transfer-Encoding: 7bit Subject: Dallas area Ham laser activity? To: laser@berlioz.nsc.com X-Mailer: SPRY Mail Version: 04.10.06.22 Sender: owner-laser@berlioz.nsc.com Precedence: bulk I got an email from John, DWNN13A@prodigy.com, asking if there was any Ham laser activity in the Dallas area. Anyone know? Sent him instructions for getting on this reflector. 73, Steve J. Noll | Ventura CA | WA6EJO | sjnoll@ix.netcom.com | http://www.netcom.com/~sjnoll/usedequip.html | http://www.netcom.com/~sjnoll/peltier.html >From owner-laser Sun Mar 16 09:38:42 1997 Return-Path: Received: by berlioz.nsc.com (4.1/SMI-4.1) id AA06150; Sun, 16 Mar 97 09:38:42 PST Date: Sun, 16 Mar 1997 12:35:17 -0500 (EST) Message-Id: <2.2.16.19970316125854.1c47414c@mail.snet.net> X-Sender: paulc@mail.snet.net X-Mailer: Windows Eudora Pro Version 2.2 (16) Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" To: laser@berlioz.nsc.com From: "Paul A. Cianciolo" Subject: is anyone actually pulsing leds out there? Sender: owner-laser@berlioz.nsc.com Precedence: bulk Hello All I would like to hear from anyone pulsing leds with high current. I am not having good luck doing this. what are you using to pulse the led? I am using a 555 timer at 400 hz and the narrowest pulse I can get. I allow 12vdc with a 10 ohm resistor to feed the led. this should allow the led to draw lots of current I would think. My 800 hz modulated led xmitter beats it on the scope for amplitude. I have a detector mounted across the room and I feed an led either the 800 hz xmitter or the pulsed voltage and look at it on the scope. 800 hz wins all the time. Any Ideas welcome Thanks 73's PaulC KB1RP >From owner-laser Sun Mar 16 11:20:49 1997 Return-Path: Received: by berlioz.nsc.com (4.1/SMI-4.1) id AA07294; Sun, 16 Mar 97 11:20:49 PST Date: Sun, 16 Mar 97 19:16:03 UT From: "John Yurek" Message-Id: To: "Laser Messages" Subject: News Flash - Laser SSB QSO ! Sender: owner-laser@berlioz.nsc.com Precedence: bulk I got to try an idea that was kicking around in the back of my head now for the past couple of months. The spark was a very recent Email from Dave AA1A. We got to talking about modulating laser diodes and he mentioned that he was BIASING his keying transistor thus allowing him to place SINEWAVE subcarriers on the laser! This means that linear modulation techniques such as AM, SSB and more importantly SIMULTANEOUS (more than one) subcarrier can be used at the same time! In the past I've been using a higher frequency subcarrier then modulating it with several lower frequency subcarriers to achieve the same end result. What I did was simply bias my series pass transistor so that the laser looked about 1/2 brilliancy. I didn't have any luck trying to make sense of the current because of the laser threshold. When the current dropped below this critical value all laser action stopped so I just eyeballed it which wasn't easy considering that this is an IR system! I have no trouble seeing it in a dark room however. I then applied a sinewave of around 20 khz and re-adjusted the bias and the level of the subcarrier for maximum output at the optical detector while aiming both at a distant target and listening to the reflected signal. After everything appeared to be working normal I hauled it all up to roof which was no picnic since it's been just above freezing here all day! My old laser buddy unfortunately moved out of the area. Our QTH's were ideal since they were about 6 miles apart and line of sight. With him I could have a 6 mile laser QSO by just aiming out the window! But those days are gone. The station I am now working with does NOT have line of sight to me but we do have a communications tower about 3 miles from me and 2 miles from him. It has 9 small radomes at the top of the tower which are pretty good at scattering IR laser energy. He can see it from his window but I have to go to the roof to see it. We established the circuit on NBFM. I then disconnected the NBFM system and connected a piece of double coax (like the dual cable TV systems use) which ran back in the house. (You didn't think I was going to spend the rest of the day freezing did you?) The other end of the coax was then reconnected to the NBFM circuits and the voice circuit re-established. The NBFM circuit was running at 25 khz. I then hooked up the VLF system. This is basically a double balanced mixer feeding into an HF transceiver. It's a project left over from the 160-190 khz VLF experiment days and has the ability to both transmit and receive on any frequency from 0 to 500 khz. (How close you can actually get to zero is another matter!) The output of the optical detector was simply connected in parallel to both the fm system and the VLF receiver input. The VLF transmit output was mixed with a couple of pots and summing resistors into the laser diode. We tried various frequencies from 10 khz to 100 khz with solid results on SSB! Although the system also worked at 250 khz and 500 khz the signals were a LOT weaker. I didn't bother to find out why but I think the optical detector that I'm using right now doesn't have an extended frequency response much above about 150 khz or so. It might even be the amp following the detector. We finally ended up leaving it at 67 khz but there wasn't a whole lot of difference on any frequency that we tried just as long as we stayed below about 100 khz and avoided the 25 khz NBFM carrier which was still running! We got to thinking, wouldn't it be nice to be able to send data as well? Then it hit us. We both have 28.8 modems than have a leased line mode. We thought about dumping these into the 25 khz NBFM circuit but decided to try baseband instead to see if we could get ALL THREE going at the same time! I had previously modified this external modem for use on a 10 ghz microwave setup so that it transmitted on a separate pair of wires from the two it was receiving on which really came in handy today. I connected the receive pair in parallel with the VLF converter and NBFM demodulator and added a third pot and mixing resistor to the transmit setup. It took a little fiddling with levels but we finally managed to get the modems connected and the carrier lights to stay on. We then logged onto each others computers and did file transfers at 28.8 kb/s while at the same time music was playing on the NBFM channel and we were talking on the SSB channel! We decided to dump music on the NBFM channel just so there was some kind of audio on it to test for interference since the two of us talking simultaneously on both audio channels didn't seem like a very good test. For these tests I was using a laser diode assembly from a printer that I bought at a hamfest at 2 for a dollar. Receiver was an unknown photodiode (most likely from a laser printer also) using optical biasing and a four inch lens on the front of it with about a 2 foot focal length. I have a red filter removed from a TV remote control over the diode to cut down interference from out of band sources of light. I've come up with a pretty nifty aiming device which I intend to write up as a construction article when time permits. It makes hitting targets like this communication tower a piece of cake. Previous to using this it took hours to get things lined up! Sometime this summer I hope to build something stable enough on the roof to allow the laser head to stay there. What I have now is just too unstable. A good gust of wind will cause things to shift around enough that we completely loose the circuit and have to start over from scratch! So there you have it. Simultaneous NBFM, 28.8 kb/s data, and SSB all at the same time over a 5 mile NON line of sight path! Let's just hope the fog doesn't roll in.... Talk about the band closing down??? John K3PGP@msn.com >From owner-laser Sun Mar 16 14:37:26 1997 Return-Path: Received: by berlioz.nsc.com (4.1/SMI-4.1) id AA09378; Sun, 16 Mar 97 14:37:26 PST From: sjnoll@ix.netcom.com Date: Sun, 16 Mar 1997 16:32:50 -0600 (CST) Message-Id: <199703162232.QAA16337@dfw-ix13.ix.netcom.com> Mime-Version: 1.0 Content-Type: text/plain Content-Transfer-Encoding: 7bit Subject: RE: is anyone actually pulsing leds out there? To: laser@berlioz.nsc.com X-Mailer: SPRY Mail Version: 04.10.06.22 Sender: owner-laser@berlioz.nsc.com Precedence: bulk Is it possible that there is something going on with the detector/detector amplifier speed? Are the 400 Hz pulses much narrower than the 800 Hz pulses? 73, Steve J. Noll | Ventura CA | WA6EJO | sjnoll@ix.netcom.com | http://www.netcom.com/~sjnoll/usedequip.html | http://www.netcom.com/~sjnoll/peltier.html >From owner-laser Mon Mar 17 01:33:35 1997 Return-Path: Received: by berlioz.nsc.com (4.1/SMI-4.1) id AA18354; Mon, 17 Mar 97 01:33:35 PST Date: Mon, 17 Mar 97 09:01:28 UT From: "John Yurek" Message-Id: To: "Laser Messages" Subject: is anyone actually pulsing leds out there? Sender: owner-laser@berlioz.nsc.com Precedence: bulk Paul: >I would like to hear from anyone pulsing leds with high current. > >I am not having good luck doing this. what are you using to pulse the led? >I am using a 555 timer at 400 Hz and the narrowest pulse I can get. I allow >12vdc with a 10 ohm resistor to feed the led. It's been my experience that you need a bit more than a 555 timer to pulse an LED to a couple of amps! First off I would suggest you put something like a 1 ohm resistor in the return lead of the LED. (This is in addition to the usual current limiting resistor and NOT in place of it!) Hang a scope across it and use ohm's law to find out exactly what the peak current is. This will also allow you to look at the pulse shape, width and amplitude. You will need a driver transistor between directly off the B+ line. This should feed the current limiting resistor to the LED. Nothing critical here except that it must be able to handle a short pulse of a couple of amps without going into meltdown! Between the 555 and the driver transistor base I suggest you insert a one shot multivibrator. This will allow independent control of pulse width. The 555 will then only be used for frequency control. You should set the one shot multivibrator for pulses of less than 1 us. If you make this pulse too long you will wipe out the LED immediately! 1 us should be the MAXIMUM if you're trying to pulse into the 1 to 2 amp region. It's possible to make this pulse longer but be careful when doing this! If you're going for 2+ amps you will most likely have to make this pulse shorter. Make sure your detector can properly detect pulses shorter than 1 us otherwise you will become very confused when trying to evaluate peak output power! Be especially careful with things like op-amps! I've had no trouble at all running a Radio Shack IR diode 2 amps. (I don't remember which one but I think it's the one with the highest mw output.) It was used in a home-brew security system and ran 24 hours a day for several years with no failures. From what I remember of it I was running a 1 us pulse length and something around 400 Hz. B+ was 12 volts. This system used a CD4049 for the oscillator and pulse shaping circuits. It had a separate pot for frequency and pulse length. Unfortunately I don't remember the circuit details right now. I know it used two gates as an oscillator and two more in series to form the pulse. The last two inverters were used in parallel to drive the base of the transistor. I think I still have one of the circuits built up but it's in the junk box someplace. I pretty much gave up on pulsing LEDs when I discovered laser diodes! If I run across it I'll set it aside because it was a pretty simple circuit only requiring a CD4049, and an NPN transistor. I might ad that I achieve my best DX record with LEDs using this circuit. Then along came laser diodes and blew everything else out of the water! When setting up your circuit do NOT use your best diode. Use something that will be no great loss should you have an accident! Even a standard red LED is a good candidate till you get things working. ----- For those of you considering trying to pulse a LASER diode ---- D O N ' T ! ! ! See my next post !!! John K3PGP@msn.com >From owner-laser Mon Mar 17 01:33:28 1997 Return-Path: Received: by berlioz.nsc.com (4.1/SMI-4.1) id AA18345; Mon, 17 Mar 97 01:33:28 PST Date: Mon, 17 Mar 97 09:02:38 UT From: "John Yurek" Message-Id: To: "Laser Messages" Subject: Don't Pulse that Laser Diode ! Sender: owner-laser@berlioz.nsc.com Precedence: bulk A while back Cliff K7RR asked about the feasibility of pulsing LASER diodes. Since then I've been looking for an old article that explained what happens to a laser diode when you try this. Before I managed to find the article Richard KD6BQ sent the exact info I was trying to find. A great BIG THANK you do Richard for saving all of us some melted silicon! >John, I wouldn't try the high current pulse experiment on any laser diodes that >you want to keep as lasers. I believe that the most common failure mode for the >lasers is optical damage to the front facet. There is always some optical >absorption at this part of the laser. The maximum operating current of the >laser is determined by the maximum optical power that the front facet will take >without being fractured. Attempted short pulse high peak power operation of most >CW diode lasers will result in them turning into expensive LED's >--Richard KD6BQ Of course there is nothing wrong with pulsing a laser diode at NORMAL operating current. But do NOT try to put something like 1 or 2 amps through it! John K3PGP@msn.com >From owner-laser Mon Mar 17 17:20:08 1997 Return-Path: Received: by berlioz.nsc.com (4.1/SMI-4.1) id AA22461; Mon, 17 Mar 97 17:20:08 PST Content-Length: 564 Message-Id: X-Mailer: XFMail 1.0 [p0] on Linux Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 8bit Mime-Version: 1.0 Date: Mon, 17 Mar 1997 19:25:44 -0500 (EST) From: wayne hilliard To: Laser Messages Sender: owner-laser@berlioz.nsc.com Precedence: bulk As I am new to laser communications I would like a couple of tips. What are some resources ie catologs etc where I can obtain parts? What is a good photodiode to use for general testing (not infrared) and where can I order it? Thanks in advance!!! Wayne Hilliard "If computers are making the world a global village, KA1CXD and I can't figure out how to use one, does that woody@sover.net make me the global village idiot ?" Shoe >From owner-laser Mon Mar 17 21:17:58 1997 Return-Path: Received: by berlioz.nsc.com (4.1/SMI-4.1) id AA27215; Mon, 17 Mar 97 21:17:58 PST Date: Mon, 17 Mar 1997 23:10:51 -0600 (CST) Message-Id: <199703180510.XAA23593@bluestem.prairienet.org> From: w9sz@prairienet.org (Zack Widup) To: laser@berlioz.nsc.com Subject: Lenses Reply-To: w9sz@prairienet.org Sender: owner-laser@berlioz.nsc.com Precedence: bulk Hi, I have downloaded and perused all the archives of the laser list. I didn't read each in detail but I will soon. I didn't see this mentioned, so I thought I'd ask if it's been tried. I bought a plastic Fresnel lens sheet at a hamfest last summer for $2. It measures 7" X 10" so I figure it has a fair amount of light-gathering capability. I tried it with a few street lights and it seems to focus fairly well on point sources at approx. infinity. I was also able to start a small brush fire in seconds in the yard on a sunny day (yes, I put it out!) I'm just curious about distortion and loss. Has anyone used these in a receiving system? It can be taped to a sheet of glass to make it lie flat. Zack W9SZ -- >From owner-laser Tue Mar 18 06:15:00 1997 Return-Path: Received: by berlioz.nsc.com (4.1/SMI-4.1) id AA09249; Tue, 18 Mar 97 06:15:00 PST From: sjnoll@ix.netcom.com Date: Tue, 18 Mar 1997 08:09:45 -0600 (CST) Message-Id: <199703181409.IAA07959@dfw-ix4.ix.netcom.com> Mime-Version: 1.0 Content-Type: text/plain Content-Transfer-Encoding: 7bit Subject: RE: Fresnel Lenses To: laser@berlioz.nsc.com X-Mailer: SPRY Mail Version: 04.10.06.22 Sender: owner-laser@berlioz.nsc.com Precedence: bulk Zack: One of my first receivers used a 10.25" diameter fresnel lens (Edmund Scientific). It was rigid enough to support itself. I mounted it inside of a metal tube made from vent pipe. Worked great. I have tried to find out what the general efficiency of a fresnel was with no luck. I have to believe that they aren't near as good as a plain glass convex lens, but have no proof of that. They aren't great at producing an extremely small point of light, so I would be wary of using them with a very small area detector. Their greatest strength is the large areas available compared to conventional lenses - which become hard to find over about 4" dia. 73, Steve J. Noll | Ventura CA | WA6EJO | sjnoll@ix.netcom.com | http://www.netcom.com/~sjnoll/usedequip.html | http://www.netcom.com/~sjnoll/peltier.html >From owner-laser Tue Mar 18 10:35:06 1997 Return-Path: Received: by berlioz.nsc.com (4.1/SMI-4.1) id AA17799; Tue, 18 Mar 97 10:35:06 PST Date: Tue, 18 Mar 97 18:04:10 UT From: "John Yurek" Message-Id: To: "Laser Messages" Subject: Lenses Sender: owner-laser@berlioz.nsc.com Precedence: bulk Zack W9SZ: Hello stranger! We've chatted many times over the years on two meter tropo! I think we may have also worked on 432? My best 'antenna' so far has been a plastic fresnel lens about the size you described! It's also the most difficult to aim because of the narrow beam width. (That gain has to come from somewhere!) Mine is taped to the inside of a glass window so that it lays flat. I suppose that you could sandwich it between two pieces of glass but I was afraid of distorting the ridges on it and since I had no problem getting it to lay flat I went with only one piece of glass. I wanted some kind of protection to keep it from getting damaged and dirty. The ridged side isn't the easiest thing to clean! I've had no problem using it at 633 nm and 700-950 nm in the IR range. However, I'm told that certain types of glass don't pass IR very well so if you are planning on using it in the IR range I suggest you test the glass first! This should not be a problem at 630 to 680 nm. The only thing to watch out for is to make sure that your detector can see the entire surface of the fresnel lens. Some detectors have a lens already built in that restricts the field of view. With a detector like this the field of view may be narrow enough that you will only use the central region of the fresnel lens and not achieve full gain. I don't think this is a serious problem with most detectors that you are likely to run into but I just thought I'd mention it. Like you I took mine outside and not only was able to start a fire but I was actually able to melt certain types of rocks! John K3PGP@msn.com >From owner-laser Tue Mar 18 10:35:07 1997 Return-Path: Received: by berlioz.nsc.com (4.1/SMI-4.1) id AA17800; Tue, 18 Mar 97 10:35:07 PST Date: Tue, 18 Mar 97 18:07:23 UT From: "John Yurek" Message-Id: To: "Laser Messages" Subject: Laser Reflectors in Orbit! Sender: owner-laser@berlioz.nsc.com Precedence: bulk Laser Reflectors in Orbit! ========= SpaceNews ========= MONDAY MARCH 10, 1997 SpaceNews originates at KD2BD in Wall Township, New Jersey, USA. It is published every week and is made available for non-commercial use. * A NEW STAR IS BORN * ====================== The 04-Mar-97 issue of OMRI Digest reported that Russia successfully carried out its first launch from the new Svobodnyi cosmodrome in Amur Oblast on 04-Mar-97, sending a Zeya military satellite into orbit aboard a Start-1 booster rocket (a modified SS-25 ballistic missile). The Zeya satellite is equipped GLONASS and GPS receivers along with 20 LASER REFLECTORS for tracking purposes. Of interest to Amateur Radio Operators is the fact that the Zeya satellite also carries a Radio Sputnik Amateur Radio communications transponder. Zeya is identified as RS-16, and Amateurs around the world have successfully copied CW telemetry transmissions from the new satellite on 29.408 MHz. OZ1MY reported hearing what sounded like slow PSK on 29.451 MHz on at least one pass. The following are the latest Keplerian elements for Radio Sputnik 16 (RS-16) from the NASA OIG RAID RBBS as provided by Ken Ernandes, N2WWD: RS-16 1 24744U 97010A 97066.14889668 .00002139 00000-0 74153-4 0 367 2 24744 97.2814 333.1163 0009586 91.5327 268.6998 15.30875098 474 John K3PGP@msn.com >From owner-laser Tue Mar 18 12:24:32 1997 Return-Path: Received: by berlioz.nsc.com (4.1/SMI-4.1) id AA21724; Tue, 18 Mar 97 12:24:32 PST Date: Tue, 18 Mar 1997 11:46:05 -0800 (PST) From: Clifford Buttschardt To: John Yurek Cc: Laser Messages Subject: Re: CCW In-Reply-To: Message-Id: Mime-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: owner-laser@berlioz.nsc.com Precedence: bulk Hi again John es all. Again I am two messages behind you. I have SOME information on pulsing LED's and more on the Santa Barbara Research communicator. This time let me reply to CCW and BPSK only. I've been experimenting with both for ten years. The last year has shown more progress than the previous five. With CCW and a great deal of effort, we would could see 25 db improvment occassionally and in the presence of white noise. On any HF path, 18 db was a better observed figgure. On BPSK we have consistently seen improvements of 15 db and ocassionally 22 db. Once again only in white noise. All experments on BPSK uses the full ASCII set----not CW! The carrier frequency was 800 hertz, most fortunately! Speeds of 25 and 40 WPM equivelent are still used on 3591.000 KHz each evening again only full ascii sets and BPSK, not CW! So it comes down to this: Unless you require full data transmission, CCW remains a better choice. Two avenues are available one using a computer and Bill DeCarles programs. The other DSP techniques that can be gotten from W9GR, Timewave or other DSP boxes, for you see they are the same thing. The only advantage in the coherent CW PCW program by Ernst Schrodeder is that a look up table is included allowing those without manual CW skills to copy code via a computer screen presentation. Cliff Buttschardt K7RR ex W6HDO Morro Bay, CA On Sun, 16 Mar 1997, John Yurek wrote: > To ALL: > > How much signal to noise improvement can be had with CCW and with the Sigma > Delta board mentioned in the VE2IQ files? > > I have been experimenting with indirect paths by bouncing laser signals off of > a common object that two stations can both see. Some of these paths can be > quite challenging. If the signal is in the noise can CCW or BPSK make it into > something useable? > > I've heard people talk about being able to read a signal that's 30 db BELOW > the noise! Although I've been able to demonstrate this on the bench, CCW > never worked this well on the air with difficult paths on HF, EME and VHF > tropo. Most of the difficulty seemed to be establishing a coherent reference > to drive the demodulator. Since I haven't done anything along these lines for > years I was wondering how well these newer techniques work. > > John > K3PGP@msn.com > >From owner-laser Tue Mar 18 14:20:18 1997 Return-Path: Received: by berlioz.nsc.com (4.1/SMI-4.1) id AA25797; Tue, 18 Mar 97 14:20:18 PST Date: Tue, 18 Mar 97 17:13:43 UT From: "John Yurek" Message-Id: To: "Laser Messages" Subject: Building a Laser MCW, NBFM, SSB System Sender: owner-laser@berlioz.nsc.com Precedence: bulk Building a Laser MCW, NBFM, SSB System ---------------------------------------------------------------- By John Yurek, K3PGP 03/18/97 This article will attempt to show how to modify the Lyte Optronics 670 nm laser light pen for use with CW, FM and SSB. First off if you haven't ordered your laser pen I suggest you get busy and order it before this offer disappears! Remember you get FREE SHIPPING when using this order number! Lyte Optronics Laser Pointer Pen Model # CPP2 <5 mw 670 nm Uses 2 AAA batteries (included) Available from: Damark 1-(800) 827-6767 Quote the following Item # and get FREE SHIPPING! ($5.99 value!) Item # B-50051-509141 Price: $24.99 Non members / $22.49 for Damark Members Remember: Shipping is FREE with the above item number and Damark has a no questions asked 60 day return policy! So if you the pen isn't as expected, put it back in the box and send it back for a complete refund! Of course this assumes you haven't drilled holes in it and have wires hanging out of it :-^) ! When I got my laser pens they came ready for use with batteries already installed. I suggest that you experiment with it for a bit to make sure all is well before starting to proceed with the modifications. Although there is nothing wrong with disassembling the laser pen my goal was to come up with a simple way to modulate the internal laser diode WITHOUT modifying the pen in any way! What you will need is a piece of small diameter insulated wire. I found a piece of copper wire from a 25 pair telephone cable to be ideal. I believe this is appox. 26 gauge with a flexible plastic coating. Strip about 3/8 of an inch of the insulation from both ends of a piece of wire about 6 inches long. Lay this aside. Carefully open the laser pen. Do this by holding the back part (with the clip) and rotating the front part until the unit opens. When you have it apart place both batteries in the front assembly if they aren't already there. Carefully stick one end of the telephone wire into the hole in the back assembly under the clip. It should be inserted to a depth of about a 1/2 inch (some insulation (approx. 1/8 inch) sticking into the hole). Now hold the back assembly and carefully re-insert the front assembly. When the first battery hits the protruding wire it will bend backwards and you will feel a bit of resistance as the wire is forced between the case and the battery holder assembly. Screw the front end back in by holding the back end and rotating the front end. Congratulations, you have now added a modulation input to your laser pen WITHOUT modifying it in anyway. Your 60 day warranty is still valid! (Just don't tell anyone what you did 'cause they would never believe you even if they did understand!) Before proceeding test the laser pen by touching the bare end of the protruding wire to the clip. The laser diode should come on. If it doesn't you will need to disassemble the unit and figure out what went wrong. Although I have had no trouble doing the above with a couple of pens, I suppose that something could go wrong to prevent the wire from contacting the internal metal battery holder especially if you are using a different diameter wire. Once everything appears to be working correctly you can proceed with the rest of the circuit. You will need an NPN transistor. The exact type doesn't seem to be critical as it will be required to carry less than 50 ma. of current. The emitter is attached to the wire and the collector is attached to the clip using a small alligator clip. Yes, you could probably solder to the clip but remember our goal is to NOT modify the laser pen in any way! Connect a 10 k resistor from base to emitter. Connect one end of a 1 k resistor to the base. Touch the free end of the 1 k resistor to the collector of the transistor. The laser diode should come on. If it doesn't short the transistor from collector to emitter. If this works you know the wire is still connected to the laser pen correctly and the problem is with the transistor. Make sure the transistor isn't connected backwards. As a last resort try another transistor! The free end of the 1 k resistor is the modulation input and can be DC coupled to a 50 % duty cycle square wave generator. This can be a simple 555 timer, a flip flop divider chain, or any other source of square waves. If your goal is modulated CW set the frequency of the square wave to an audible rate. Although most stations using laser communications have been using 800 Hz as a standard I find that my ears peak at a much lower frequency, around 575 Hz. If you want to use the pen for voice work you should set the frequency of the square wave to around 25 KHz. This isn't at all critical as the pen will work with frequencies up to approx. 100 KHz but there will be a drop off in performance with the higher frequencies due to the action of the internal power regulator circuit in the pen. The square wave generator should have the capability of being fm modulated linearly over a range of +- 3 to 5 KHz. There are many function generator VCO chips on the market that are made specifically for this purpose but there is nothing wrong with a simple 555 timer circuit. However, if you are going to use a free running VCO I suggest that you use a decent capacitor that is temperature stable. A ceramic disk capacitor is a NO-NO here unless you want to do remote temperature sensing by reading the frequency of the 25 KHz subcarrier! When you apply the square wave to the base of the transistor the laser diode should come on and look just about as bright as it did before the modifications. If you are using the lower frequency for MCW you can verify that the laser diode is being modulated by rapidly waving the pen back and forth and looking at the projected beam on the wall or ceiling. You will see that it is being rapidly turned on and off as indicated by the short dashed lines! You most likely will have difficulty observing this effect when using the 25 KHz subcarrier unless you can wave you hand a lot faster than I can! RECEIVING THE SIGNAL ------------------------------------- Since the purpose of this article is to describe how to modify the Optronics CPP2 Lyte Pen for use with MCW, FM and SSB I will not go into detail as to how to build an optical front end. There have already been many good articles on this in the literature. If you are using MCW you can simply dump the output of the optical front end into an audio amplifier and speaker. However, you will most likely need some help with the FM voice system if this is your first experience using low frequency subcarriers! My favorite system which I use to compare all FM demodulation schemes to is a VLF converter setup feeding a communications receiver. This setup is tuned to the frequency of the subcarrier in use, in this case 25 KHz. Although it's very desirable to use a receiver with a built in NBFM demodulator don't worry about it if yours doesn't. You can detect NBFM modulation by using slope detection on most AM receivers. Simply tune off to one side and you will hear the NBFM modulation. However, using an AM system to demodulate NBFM is far from ideal and should be used only if nothing else is available! A word of caution on using the VLF converter setup. Be careful to NOT overload the input of the VLF converter. Most of these are quite sensitive. Many optical front ends can put out several volts of signal! You may need to attenuate the signal before you connect it to the VLF converter. You can do this with a simple pot hooked up just like a volume control between the optical front end and the VLF converter. Once you find the correct value you can either use the system like this or remove the pot and solder in the correct resistors. If your S-Meter on the communications receiver is against the pin you definitely need an attentuator! Once you have this going I'm sure you will want to make a portable setup so you don't have to drag the VLF setup around with you! I have had very good results using a single stage op-amp filter feeding a CD4046 PLL used as an NBFM demodulator. If you go this route avoid the temptation to beef up the filter ahead of the PLL. The system will actually work extremely well without the filter. If you make the filter too sharp the entire system will suffer or fail to work at all. The filter should only be down approx. -3db at 20 and 30 KHz to properly pass the NBFM signal to the PLL. This doesn't require much in the way of a filter and for most laser QSOs you won't notice any difference with it in or out since the PLL itself is a fairly good filter when used as an NBFM demodulator. However, weak signal performance is slightly better with the op-amp filter ahead of the PLL. It is also possible to upconvert like the above VLF converter system. For this setup I like to use a double balanced mixer with NO RF stage. You can either buy one of these already made up or make one out of 4 diodes and a couple of toroids. I'm using two junk box toroids and four 1N914 diodes. The choice of a local oscillator depends on the receiver that you want to use. Some nice choices are 3.5 MHz or 7 MHz when using HF equipment, 100.000 MHz when using an R-7000 general coverage 25 to 2000 MHz all mode receiver, (If using 100.000 MHz you will most likely have to shield everything to keep out strong FM stations!) or 144.000 MHz when using an FM handheld. In the later case you can use a 48.000 MHz crystal into a tripler to get 144.000. (I chose 144.000 MHz to keep strong FM repeaters out of the system! This is extremely nice for mountaintopping as you can always come up with a two meter handheld! To use this with the laser NBFM system above you would tune to 144.025 MHz. LASER SSB ------------------ It is also possible to use the above setup on SSB! All that is required is to bias the NPN transistor on the laser pen so that the beam is approx. half brilliance. Unfortunately determining where this is isn't that easy but in actual practice it isn't that critical. You can NOT do this by measuring the current into the laser pen. If you do you will run into an effect called laser threshold. This is a very sharp knee where the diode changes characteristics from an expensive LED into a laser diode. In the case of the CPP2 laser pen this occurs around 23 to 25 ma. Below this critical value you get no laser action. Much above this and you stand a good chance of wiping out the laser diode. Yes, unfortunately laser diodes live right on the edge of self destruction! You won't have to worry about over current with this circuit though because the internal power regulator in the pen will prevent this. What you need to do is connect a third resistor from base to collector of the NPN transistor. Adjust it's value till the laser appears to dim down a bit. With proper test equipment you will be able to set this to optimum. I won't go into details here since it isn't that critical when getting the system up and running. The SSB signal is applied to the free end of the 1 K resistor coming from the base of the NPN transistor through a coupling capacitor. The actual value isn't critical just so it is large enough to pass the subcarrier frequency. A low voltage 0.1 mfd is fine for 25 KHz but you might want to make it a bit bigger if using baseband voice or MCW. In that case I would suggest something like 10 mfd. When modified as above the laser pen can be modulated with any type of signal including sinewaves, baseband voice and CW and since it is linear it can handle more than one subcarrier simultaneously! To put SSB on it you will need as source of VLF SSB at approx. 25 KHz. Remember the above description of the double balanced mixer? Well if you turn it around and transmit into it (at very low power of course < 1 milliwatt !) you will DOWNCONVERT to 25 KHz! Feed this downconverted signal into the base of the NPN transistor and you're now on laser SSB! You will have to optimize the bias on the transistor and set the level of the 25 KHz SSB signal feeding the base. About the same procedure as setting up a linear amplifier! For receiving you will need an upconverter and SSB receiver. The SAME double balanced mixer can be used for both transmit and receive if using a transceiver! If you have a separate receiver and transmitter you can either use relays to switch the system or you might want to think about two double balanced mixers, one for transmit and one for receive using a common local oscillator feeding both. I was fortunate to come up with a pair of two meter multi-mode handhelds many years ago. These are very nice since one radio can be used for NBFM, SSB, and direct two meter contact. In one experimental QSO I had three signals on the laser pen simultaneously. At 25 KHz I had the NBFM subcarrier system. At 67 KHz we were talking on SSB. On the baseband feeding directly into the NPN transistor) we had a couple of 28.8 kb/s modems running in leased line mode doing file transfers via computer! The input to the NPN transistor is extremely sensitive when biased in a linear fashion. It is quite easy to detect signals of less than 1 microvolt. With that in mind, during one memorable QSO I had the distant station pull all the subcarriers off the system and substitute a long wire antenna. On the receive end I was able to hear on the air stations from VLF through the short-wave broadcast band at 9 MHz! This test was done using a laser diode transmitter with a power regulator circuit that does NOT exhibit the roll off at 100 KHz that the CPP2 pen does. Unfortunately the optical front end that I was using rolls off around 10 MHz so I don't know what if anything was being transmitted above that frequency. Keep in mind that the CPP2 pen does roll off quite severely as the frequency goes up so if you have interest in using higher subcarrier frequencies you will have to completely tear the pen apart and rebuild the internal power regulator. In my mind you would be better off to leave the CPP2 laser pen system alone and pick up a couple of IR or 670 nm laser diodes at the next hamfest and start from scratch! I'm working on a cheap source of IR laser diodes and detectors so stay tuned! So there you have it. A $25 laser pen system capable of transmitting MCW, NBFM and SSB! John K3PGP@msn.com >From owner-laser Wed Mar 19 03:44:35 1997 Return-Path: Received: by berlioz.nsc.com (4.1/SMI-4.1) id AA23672; Wed, 19 Mar 97 03:44:35 PST Message-Id: <199703191142.GAA03389@host-04.colby.edu> X-Sender: aballen@colby.edu X-Mailer: Windows Eudora Light Version 1.5.2 Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Date: Wed, 19 Mar 1997 06:42:49 -0500 To: "John Yurek" From: "Art Allen, KY1K" Subject: Re: Building a Laser MCW, NBFM, SSB System Cc: laser@berlioz.nsc.com Sender: owner-laser@berlioz.nsc.com Precedence: bulk >You will need an NPN transistor. The exact type doesn't seem >to be critical as it will be required to carry less than 50 ma. of current. ------------------------------------ >very sharp knee where the diode changes characteristics from an expensive >LED into a laser diode. In the case of the CPP2 laser pen this occurs around >23 to 25 ma. Below this critical value you get no laser action. Hey John and the group... This is a FB job of writing and just the kind of stuff we need on the laser list! Thans to John for taking the time to put this info out! I'd grab one of these pens right now, except I'm not so sure about the power output. The knee current for the laser pen is '23 to 25' ma. And the only specs we have for power output is '<5mw'. I was looking at the TOLD9412 3 mw diodes recently and their knee current is 70 ma. I'd like to have a high power TX, and it appears that the laser pen ISN'T-taking a guess based on the lasing current, one might guess that it was around 1 mw out. Does anyone in the group have access to an accurate power measuring device? I'd really like to know what the actaul measured power output is. Ideas/commants? GL...Art, KY1K. >From owner-laser Wed Mar 19 07:28:16 1997 Return-Path: Received: by berlioz.nsc.com (4.1/SMI-4.1) id AA29744; Wed, 19 Mar 97 07:28:16 PST Message-Id: <199703191524.KAA17327@host-04.colby.edu> X-Sender: aballen@colby.edu X-Mailer: Windows Eudora Light Version 1.5.2 Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Date: Wed, 19 Mar 1997 10:25:04 -0500 To: Clifford Buttschardt From: "Art Allen, KY1K" Subject: Re: CCW Cc: laser@berlioz.nsc.com Sender: owner-laser@berlioz.nsc.com Precedence: bulk Hey Cliff, I've been looking at detecting the presence of light, or its absence-without modulating the carrier at all! It appears to me that simple cascaded RC networks, until the bandwidth approaches 3 to 10 hz, should work well for slow cw. Of course, this trades SPEED (bandwidth) for RANGE (s/n ratio). If I was willing to modulate the laser, would ccw provide enhanced copy for a weaker input signal? If I can get 20 chars per second thruput, then I can complete a qso 'meteor scatter style' by mechanically damping a hand held aiming mechanism and sweeping across the target! No need for an elaborate/stable aiming platform at all! One more question.... Is it really as simple as 'just plugging in a comm'l dsp unit'? While they aren't cheep to purchase, neither are laser tx's that are 15-20 db stronger hi hi! How does a super scaf compare ? I have a super scaf, and its performance is remarkable. Beginners info on this topic? Tell me more. Art, KY1K. PS: Some might be interested to know that in the earlier days of my dubbing around, one of the experiments I did involved aiming a laser by hand. I don't think I ever published the results and the results weren't very 'quantifiable'. I mounted a laser on a target rifle with post sights. I placed a target about 800 feet downrange with an LED near the target in order to provide something to aim at. By simply leaning against a post or resting against something solid, I could aquire the target in just a few seconds. By listening to the received audio (from the target RX) via a 2 meter radio link, I could easily hold that laser on the target and provide a constant tone with very very slight QSB. My guess is that a similar setup (pivot mount and a heads up alt az readout and mechanical damping) would provide similar 'target lock' without the need for real time feedback from the target. At 11:46 AM 03/18/1997 -0800, you wrote: >Hi again John es all. Again I am two messages behind you. I have SOME >information on pulsing LED's and more on the Santa Barbara Research >communicator. This time let me reply to CCW and BPSK only. I've been >experimenting with both for ten years. The last year has shown more >progress than the previous five. With CCW and a great deal of effort, we >would could see 25 db improvment occassionally and in the presence of >white noise. On any HF path, 18 db was a better observed figgure. On >BPSK we have consistently seen improvements of 15 db and ocassionally >22 db. Once again only in white noise. All experments on BPSK uses the >full ASCII set----not CW! The carrier frequency was 800 hertz, most >fortunately! Speeds of 25 and 40 WPM equivelent are still used on >3591.000 KHz each evening again only full ascii sets and BPSK, not CW! > So it comes down to this: Unless you require full data transmission, >CCW remains a better choice. Two avenues are available one using a >computer and Bill DeCarles programs. The other DSP techniques that can be >gotten from W9GR, Timewave or other DSP boxes, for you see they are the >same thing. The only advantage in the coherent CW PCW program by Ernst >Schrodeder is that a look up table is included allowing those without >manual CW skills to copy code via a computer screen presentation. >Cliff Buttschardt K7RR ex W6HDO Morro Bay, CA > > > > On Sun, 16 Mar 1997, John Yurek wrote: > >> To ALL: >> >> How much signal to noise improvement can be had with CCW and with the Sigma >> Delta board mentioned in the VE2IQ files? >> >> I have been experimenting with indirect paths by bouncing laser signals off of >> a common object that two stations can both see. Some of these paths can be >> quite challenging. If the signal is in the noise can CCW or BPSK make it into >> something useable? >> >> I've heard people talk about being able to read a signal that's 30 db BELOW >> the noise! Although I've been able to demonstrate this on the bench, CCW >> never worked this well on the air with difficult paths on HF, EME and VHF >> tropo. Most of the difficulty seemed to be establishing a coherent reference >> to drive the demodulator. Since I haven't done anything along these lines for >> years I was wondering how well these newer techniques work. >> >> John >> K3PGP@msn.com >> > > > >From owner-laser Wed Mar 19 09:57:57 1997 Return-Path: Received: by berlioz.nsc.com (4.1/SMI-4.1) id AA05748; Wed, 19 Mar 97 09:57:57 PST Date: Wed, 19 Mar 97 17:28:42 UT From: "John Yurek" Message-Id: To: "Laser Reflector" Subject: Building a Laser MCW, NBFM, SSB System Sender: owner-laser@berlioz.nsc.com Precedence: bulk Art: I share your feelings on the CPP2 Laser Pen regarding power output. On the box it says <5 mw output 630-670 nm! On the pen it says Power Output 1 mw 670 nm! Like you I'm more inclined to believe the 1 mw figure although it looks kind of bright for a 1 mw unit when doing A/B tests with other pens. I'd be inclined to place it around 2 mw. I know there are some people on here with power measuring equipment so we'll just have to wait for them to get one of these pens. However, I don't know if measuring just one pen would really settle anything. In the last couple of days I've had the opportunity to measure a couple more of these pens and the current varies all over the place (from a low of 20 ma to a high of 95 ma!) even though all look the same brightness and produce the just about the same amount of current when aimed at a silicon solar cell and milliamp meter used as a power output indicator. I can't say that the ones pulling 95 ma are producing any more output. In fact some of these are actually making less output than some pulling <25 ma. The bottom line is I don't think much can be learned from the current consumption. I have had the same experience with IR laser diodes. Some that pull over 150 ma don't produce any more output than others pulling 65 ma. One of my highest power output IR lasers only pulls around 55 ma! Of course I could run the current up on any laser diode but after playing around with many of them you kind of get a feeling for when you shouldn't push things! Originally I thought the ones pulling the high current were damaged but after checking more than one it just seems to be characteristic of that particular brand of diode. Did you ever stop to think just what you would gain by using a 4 mw laser instead of a 1 mw laser? So you would be 6 dB stronger. On any line of sight path that I've used it wouldn't have made any difference. The only place I could see this to be a factor might be on an indirect scatter path. However, that 6 dB pales by comparison with what can be done with simple optics. With a 6 inch parabolic mirror you can easily pick up over 100 dB of system gain. Gains of 40 or 50 dB are easily achieved even with very small simple lens. (By the way that reminds me. I have some good info on CHEAP 4 and 6 inch parabolic mirrors. I'll dig it up and post it as soon as I find it! These are high quality and suitable for telescope making so they should produce full gain in a laser system. I even have a web adr. for these!) If your goal is to really push the DX limit then I wouldn't be fooling around with any of the visible light pens. I'd go find myself as high a power IR diode that I could afford. With CD-R recorders becoming more popular 35 mw IR diodes are rapidly dropping in price. (Now you're talking a worthwhile increase in power!) It's been my experience that most of the readily available detectors are significantly better in the IR range than they are at 630-670 nm and the most powerful laser diodes are in the IR range. I have noticed from time to time several people on the reflector asking what other people are using for detectors but have never seen any response. Unfortunately, all of mine have come from junked CD/CD-ROM players, laser printers, and scanners so I don't have a clue as to what I'm using and can't be of much help. I'd really like to go buy some known detectors to compare with but so far I don't have any numbers. I'd also like to see some dBm ratings on these so I could plug numbers into path loss equations! About the only one I've come up with (out of a 1978 data book!) was for the HP 5082-4207 and HP 5082-4220 (same diode different case) which is spec'd at an Nep of -108 dBm. I DO know that the PMT blows away any kind of solid state detector that I have. However, many of these start to fall off in performance in the IR range. So in this case the visible light pens may actually be a better choice depending on the spectral response of the particular PMT that you have. The only thing I don't like about PMTs is that they are easily damaged by exposure to bright light. A single exposure to sunlight can cause the noise floor to come up significantly and it takes days for it to recover. Sometimes it never does! I'm also looking for a source of PMT (Photo Multiplier Tubes). Anyone have any suggestions on solid state detectors and sources of PMTs? John K3PGP@msn.com >From owner-laser Wed Mar 19 09:57:56 1997 Return-Path: Received: by berlioz.nsc.com (4.1/SMI-4.1) id AA05741; Wed, 19 Mar 97 09:57:56 PST Date: Wed, 19 Mar 97 17:34:55 UT From: "John Yurek" Message-Id: To: "Laser Reflector" Subject: Cast Parabolic Mirrors Sender: owner-laser@berlioz.nsc.com Precedence: bulk Cast Parabolic Mirrors -------------------------------- There is a company advertising mirrors for telescopes at very low prices. They claim to have developed a method for casting them instead of grinding them, therefor greatly reducing the labor required to make them. Opticast Corporation http://www.diamondsports.com/opticast/index.html (NOTE: This site can be s-l-o-w at times. It took me 4 minutes to get any response the first time! Other times it zips along!) Phone 505-836-0502 Parabolic replica mirrors 1/4 wave pv: 4" f/4 29.95 6" f/4 49.95 8" Also available ($79.95) but I don't think in single quantity??? John K3PGP@msn.com >From owner-laser Wed Mar 19 11:39:27 1997 Return-Path: Received: by berlioz.nsc.com (4.1/SMI-4.1) id AA10296; Wed, 19 Mar 97 11:39:27 PST From: daveaa1a@ssih.com Date: Wed, 19 Mar 1997 14:09:06 -0500 Message-Id: <199703191909.OAA25845@ssih.com> Mime-Version: 1.0 Content-Type: text/plain Content-Transfer-Encoding: 7bit Subject: SSB - DATA - SUBCARRIERS etc.. To: laser@berlioz.nsc.com X-Mailer: SPRY Mail Version: 04.00.06.17 Sender: owner-laser@berlioz.nsc.com Precedence: bulk Gudday, Rough guess with 3mw diode is some efficiency factor and I peg it to 1mw or the equivalent of 0 dbm on the sig gen. >From there the RELATIVE db range can be seen by substituting the sig. gen. output range versus the diode shining dead into the detector.. I measure about 124 dbm range and it looks the equivalent of about 3 uv. sensitivity to me. My best front end to date is the VTP diode reverse biased with a 82k resistor back to filtered 9 vdc.. coupled with a .1 to the gate of a mpf-102 which sees a 1 meg to gnd. A 1.2k resistor in the drain lead, bypased and the source resistance of 500 ohm coupled via a .1 into the DBMixer with a L.O. of 4 mhz. gives me s-1 noise floor on the TS930 receiver at 4++ mhz. with the VLF converter running.. The main advantage of subcarrier I see is greatly diminished base band sounds from noisey lights, car headlights, rain drops, ambient, etc.. At 40 khz things get pretty quiet and i track a 124 dbm difference there between the full ON signal from the laser diode into the pin detector at dark/noisey signal and this sounds more like a communications receiver sensitivity/dynamic range all the time.. I am using the transverter IN/OUT from the hf rig to limit the power during transmit which can run duplex using different tx/rx and different sub frequencies or simplex using the same subcarrier/rig.. This system allows me to tune to baseband for basic cw/am phone set ups and almost any subcarrier freq. for ANY type of modulation ssb/fm/data etc.. The carrier as seen in a 800hz beat into the CCW/BPSK tuning utility ala VE2IQ shows a very stable carrier with resolution to well within 1 hz., enough for easy CCW and the accompanied S/N improvement but as it stands now is only needed on a very noisey circuit.. I hope this running commentary is helpful, it sure lets me see my own thoughts more clearly.. Lets hear from you.. 73 de daveaa1a >From owner-laser Wed Mar 19 15:09:54 1997 Return-Path: Received: by berlioz.nsc.com (4.1/SMI-4.1) id AA18728; Wed, 19 Mar 97 15:09:54 PST From: daveaa1a@ssih.com Date: Wed, 19 Mar 1997 17:56:21 -0500 Message-Id: <199703192256.RAA28782@ssih.com> Mime-Version: 1.0 Content-Type: text/plain Content-Transfer-Encoding: 7bit Subject: SSB - DATA - SUBCARRIERS etc.. To: laser@berlioz.nsc.com X-Mailer: SPRY Mail Version: 04.00.06.17 Sender: owner-laser@berlioz.nsc.com Precedence: bulk To: laser@berlioz.nsc.com Gudday, Rough guess with 3mw diode is some efficiency factor and I peg it to 1mw or the equivalent of 0 dbm on the sig gen. >From there the RELATIVE db range can be seen by substituting the sig. gen. output range versus the diode shining dead into the detector.. I measure about 124 dbm range and it looks the equivalent of about 3 uv. sensitivity to me. My best front end to date is the VTP diode reverse biased with a 82k resistor back to filtered 9 vdc.. coupled with a .1 to the gate of a mpf-102 which sees a 1 meg to gnd. A 1.2k resistor in the drain lead, bypased and the source resistance of 500 ohm coupled via a .1 into the DBMixer with a L.O. of 4 mhz. gives me s-1 noise floor on the TS930 receiver at 4++ mhz. with the VLF converter running.. The main advantage of subcarrier I see is greatly diminished base band sounds from noisey lights, car headlights, rain drops, ambient, etc.. At 40 khz things get pretty quiet and i track a 124 dbm difference there between the full ON signal from the laser diode into the pin detector at dark/noisey signal and this sounds more like a communications receiver sensitivity/dynamic range all the time.. I am using the transverter IN/OUT from the hf rig to limit the power during transmit which can run duplex using different tx/rx and different sub frequencies or simplex using the same subcarrier/rig.. This system allows me to tune to baseband for basic cw/am phone set ups and almost any subcarrier freq. for ANY type of modulation ssb/fm/data etc.. The carrier as seen in a 800hz beat into the CCW/BPSK tuning utility ala VE2IQ shows a very stable carrier with resolution to well within 1 hz., enough for easy CCW and the accompanied S/N improvement but as it stands now is only needed on a very noisey circuit.. I hope this running commentary is helpful, it sure lets me see my own thoughts more clearly.. Lets hear from you.. 73 de daveaa1a >From owner-laser Wed Mar 19 16:15:23 1997 Return-Path: Received: by berlioz.nsc.com (4.1/SMI-4.1) id AA21686; Wed, 19 Mar 97 16:15:23 PST Date: Thu, 20 Mar 97 00:04:14 UT From: "John Yurek" Message-Id: To: "Laser Reflector" Subject: VTP Diode ? Sender: owner-laser@berlioz.nsc.com Precedence: bulk Great commentary Dave! Lets have more like it! > My best front end to date is the VTP diode reverse biased with a 82k resistor back to OK for those of use that don't know, what's a VTP diode and where do we get one??? John K3PGP@msn.com >From owner-laser Wed Mar 19 18:10:52 1997 Return-Path: Received: by berlioz.nsc.com (4.1/SMI-4.1) id AA26614; Wed, 19 Mar 97 18:10:52 PST Content-Length: 702 Message-Id: X-Mailer: XFMail 1.0 [p0] on Linux Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 8bit Mime-Version: 1.0 Date: Wed, 19 Mar 1997 20:48:45 -0500 (EST) From: wayne hilliard To: Laser Messages Sender: owner-laser@berlioz.nsc.com Precedence: bulk I just bought one of those LaserLyte pens from damark and was wondering about the markings. <5 mw and on pen 1 mw. It sounds like it still might be a good starting laser. Once I get my photo diodes in and I start testing I guess I'll find out. By the way anybody ever try a reflecting telescope for laser work? I have a 4.5 inch meade scope gathering dust and figured it might just work out!! Opinions? Wayne Hilliard "If computers are making the world a global village, KA1CXD and I can't figure out how to use one, does that woody@sover.net make me the global village idiot ?" Shoe >From owner-laser Wed Mar 19 19:21:11 1997 Return-Path: Received: by berlioz.nsc.com (4.1/SMI-4.1) id AA29288; Wed, 19 Mar 97 19:21:11 PST Date: Thu, 20 Mar 97 03:14:50 UT From: "John Yurek" Message-Id: To: "Laser Reflector" Subject: PMT Info Sender: owner-laser@berlioz.nsc.com Precedence: bulk I was asked by someone for specs on the following tubes: Hamamatsu Photomultiplier, model R647-01 Hamamatsu Photomultiplier, model 5563147 Can anyone help? Thanks John K3PGP@msn.com >From owner-laser Thu Mar 20 06:18:43 1997 Return-Path: Received: by berlioz.nsc.com (4.1/SMI-4.1) id AA21658; Thu, 20 Mar 97 06:18:43 PST From: sjnoll@ix.netcom.com Date: Thu, 20 Mar 1997 08:14:09 -0600 (CST) Message-Id: <199703201414.IAA04019@dfw-ix10.ix.netcom.com> Mime-Version: 1.0 Content-Type: text/plain Content-Transfer-Encoding: 7bit Subject: R647-01 PMT specs To: laser@berlioz.nsc.com X-Mailer: SPRY Mail Version: 04.10.06.22 Sender: owner-laser@berlioz.nsc.com Precedence: bulk R647-01 1/2" dia head-on Selected for scintillation counting. 10-stage bialkali photocathode 300nm - 650nm, 420 nm peak Anode-Cathode 1250V max. Anode-Last dynode 250V max. 0.1 mA avg anode current max. Cathode sensitivity: 90 uA/lm typ., 85 mA/W typ. Anode sensitivity: 90 A/lm typ., 8.5 x 10^4 A/W typ. Current amplification: 1 x 10^6 typ. Anode dark current: 1 nA typ. Rise time: 2.3 nS typ. Looks great at blue, pretty crappy at 670 nm. 73, Steve J. Noll | Ventura CA | WA6EJO | sjnoll@ix.netcom.com | http://www.netcom.com/~sjnoll/usedequip.html | http://www.netcom.com/~sjnoll/peltier.html >From owner-laser Thu Mar 20 07:26:49 1997 Return-Path: Received: by berlioz.nsc.com (4.1/SMI-4.1) id AA24091; Thu, 20 Mar 97 07:26:49 PST From: daveaa1a@ssih.com Date: Thu, 20 Mar 1997 10:23:43 -0500 Message-Id: <199703201523.KAA04245@ssih.com> Mime-Version: 1.0 Content-Type: text/plain Content-Transfer-Encoding: 7bit Subject: Re: VTP Diode ? To: "John Yurek" , "Laser Reflector" In-Reply-To: X-Mailer: SPRY Mail Version: 04.00.06.17 Sender: owner-laser@berlioz.nsc.com Precedence: bulk On Thu, 20 Mar 97, "John Yurek" wrote: >OK for those of use that don't know, what's a VTP diode and where do we get >one??? I'm using a EG&G Vactec p/n VTP1188S available from Newark Electronics.. Newark p/n 95f9029.. This is the type in the original Steve Knoll receiver.. It 'sees' down into the equivalent range of LOW RF microvolts.. The frequency response is like looking down on the space shuttle..Fairly good out to 100khz then a slope down to noise at about 500khz.. They cost about $2.50... Am looking for better and don't know what to make of the specs. in the catalog.. For instance 'dark current' picoamps, nanoamps.. Is lower better?? Bandwidth, how do you tell?? There seems to be two price ranges, 3 and 30 dollars.. 73 de daveaa1a >From owner-laser Thu Mar 20 07:38:32 1997 Return-Path: Received: by berlioz.nsc.com (4.1/SMI-4.1) id AA24502; Thu, 20 Mar 97 07:38:32 PST Date: Thu, 20 Mar 97 15:37:06 UT From: "John Yurek" Message-Id: To: "Laser Reflector" Sender: owner-laser@berlioz.nsc.com Precedence: bulk Wayne: >>By the way anybody ever try a reflecting telescope for laser work? >>I have a 4.5 inch meade scope gathering dust and figured it might just work out! >I have a 4.5 inch also. Should work fine but be prepared to spend some time aiming it! If I were you I'd use it on receive and use the pen as is for transmit for now. One word of caution that I left out of the previous post. I don't think I need to warn you but do NOT look through the telescope or the finder scope at a laser! Even very low power lasers when focused by optics like this can cause some serious problems! NOTE for all newcomers: "DO NOT LOOK INTO LASER WITH REMAINING EYE!" I guess this was from an old timer that tried it ...... ONCE! John K3PGP@msn.com >From owner-laser Thu Mar 20 07:33:00 1997 Return-Path: Received: by berlioz.nsc.com (4.1/SMI-4.1) id AA24320; Thu, 20 Mar 97 07:33:00 PST Date: Thu, 20 Mar 97 15:26:48 UT From: "John Yurek" Message-Id: To: "Laser Reflector" Sender: owner-laser@berlioz.nsc.com Precedence: bulk Wayne: >By the way anybody ever try a reflecting telescope for laser work? >I have a 4.5 inch meade scope gathering dust and figured it might just work out! I have a 4.5 inch also. Should work fine but be prepared to spend some time aiming it! If I were you I'd use it on receive and use the pen as is for transmit for now. >I just bought one of those LaserLyte pens from damark and was wondering about >the markings. <5 mw and on pen 1 mw. It sounds like it still might be a good >starting laser. EXACTLY! Although it may not be the optimum it's readily available and my reason for posting it was to get people out there to start building and experimenting! In your case it looks like it worked. Congratulations! I think the manufacturer is trying to cover themselves legally as there are federal regulations regarding lasers. I don't think these pens are 5 mw but I don't think they're 1 mw either! Worse case though there's only 6 dB of difference between 1 mw and 4 mw (<5 mw ?) and on most line of sight paths you'll never notice this. Other people have checked a number of SIMILAR type pens at 2 to 2.5 mw. If the laser bug bites and you get really serious later on, at least you will have gained a lot of first hand knowledge and know exactly what you want for a better system. Not bad for a $25 investment! >Once I get my photo diodes in and I start testing I guess I'll find out. OK. Your turn to help everyone out! What did you choose for a photo diode? Price and supplier? Thanks ! John K3PGP@msn.com NOTE for all newcomers: "DO NOT LOOK INTO LASER WITH REMAINING EYE!" >From owner-laser Thu Mar 20 07:26:34 1997 Return-Path: Received: by berlioz.nsc.com (4.1/SMI-4.1) id AA24082; Thu, 20 Mar 97 07:26:34 PST From: daveaa1a@ssih.com Date: Thu, 20 Mar 1997 10:23:54 -0500 Message-Id: <199703201523.KAA04256@ssih.com> Mime-Version: 1.0 Content-Type: text/plain Content-Transfer-Encoding: 7bit Subject: Re: SSB - DATA - SUBCARRIERS etc.. To: Clifford Buttschardt Cc: laser@berlioz.nsc.com In-Reply-To: X-Mailer: SPRY Mail Version: 04.00.06.17 Sender: owner-laser@berlioz.nsc.com Precedence: bulk On Wed, 19 Mar 1997, Clifford Buttschardt wrote: >Dave---great experiment! Are you using 67 KHz subcarrier for these >experiments or something in the LOWFER band? Cliff K7RR Hi Cliff.. 67khz was an easy start because I had some left over sca FM receivers from the broadcast days..a simple 555 does 67 khz tx real easy.. With the comm. transceiver you can tune to ANY subcarrier and mode from 0 hz to over 100 khz in my case with these photo diodes (Vactec VTP-1188s).. The IC-706 is a natural for the 10ghz stuff and lets me monitor the brick frequency as well when out in the field..The way I use minimum control wiring and ease of operation is to modify a mast mounted pre-amplifier so that i get a low noise boost out of the sma mixer and when I transmit (10watts @ 146 mhz) the mast preamp keys and I modify the normal transmit 'THROUGH RELAY CONTACTS' with a combination Load/Attenuator to end up with 10mw drive for the same sma mixer..Sure keeps me from frying the precious mixer.. This is on 10 ghz.. Why not the same for Light.. I plan the same type set-up for laser.. Can't see why it won't work there.. Also with this set-up I only need one rg58 coax going to the remote dish mounted transverter with the 12 volts multiplexed up the coax. as well... I'm making 40khz home base because there are lots of remote control surplus electronics out there using this freq.. but again the comm transceiver does away with any one freq. restriction.. For instance my TV remote control lets me know relative receiver sense from baseband up to ?? there are lots of spurs going way up in freq.. The above remote RF sensing pre-amp has saved me much grief.. I will modify the RF bandpass to a broadband/baseband preamp out to 100khz++..?? Video/data when i find the right diode.. I use a mpf-102 pre-amp with these diodes to make the noise floor detectable through the VLF converter and into the comm. receiver.. For instance; with the 650nm diode pointed across the room with a 40khz carrrier modulated full and reflecting off a dark opaque surface yields a signal of 40 over 9...back to s-1 when covered.. this is with the plastic fresnel 8.5x11" lense.. (verrryyy sharp).. Are we having fun yet?? ;-) 73 de daveaa1a >From owner-laser Thu Mar 20 07:26:56 1997 Return-Path: Received: by berlioz.nsc.com (4.1/SMI-4.1) id AA24107; Thu, 20 Mar 97 07:26:56 PST From: daveaa1a@ssih.com Date: Thu, 20 Mar 1997 10:23:47 -0500 Message-Id: <199703201523.KAA04248@ssih.com> Mime-Version: 1.0 Content-Type: text/plain Content-Transfer-Encoding: 7bit Subject: Re: To: wayne hilliard , Laser Messages In-Reply-To: X-Mailer: SPRY Mail Version: 04.00.06.17 Sender: owner-laser@berlioz.nsc.com Precedence: bulk On Wed, 19 Mar 1997, wayne hilliard wrote: By the way anybody ever try a reflecting telescope for laser work? Makes a dandy collector... I'm checking out the difference between a stationary store page magnifier versus a 6" personal magnifying mirror.. The plastic fresnel lense sure works good and that larger area means more gain but you can see the distortion if you put the lense up to your eye and focus out till the pin of light fills the lense area, however there are lots of VOIDS in the circle of light..Maybe one of those personal magnifying mirrors has less distortion and more net light to the diode, will let you know.. 73 de daveaa1a >From owner-laser Thu Mar 20 10:18:55 1997 Return-Path: Received: by berlioz.nsc.com (4.1/SMI-4.1) id AA01365; Thu, 20 Mar 97 10:18:55 PST Date: Thu, 20 Mar 97 18:06:21 UT From: "John Yurek" Message-Id: To: "Laser Reflector" Subject: More on the Damark Laser Pens Sender: owner-laser@berlioz.nsc.com Precedence: bulk The Damark Lyte Optronics Laser Pens --------------------------------------------------------- Since there has been quite a bit of interest in these pens and some discussion about power levels I went back and did a bit of research into power levels. I didn't bother with this before because my goal was to come up with a simple laser transmitter that anyone could put together in a couple of hours. With that done I now had some free time to do some measurements on the pen itself. I mentioned in previous posts that I was observing some differences between pens as far as current consumption was concerned. Well I got two more in the mail today and one of the pens was noticeably brighter than any of the others. So that started the investigation! I measured the current on this pen and found it go be around 50 ma! I then substituted the batteries from one of the other (NEW) pens and the current was now 30 ma and the pen was noticeably dimmer! Hmmmmmm..... How many guessed what I'm thinking????? I took one of the dimmest pens and put three batteries in series, the two in the pen and one external. It now pulled 45 ma and looked about as bright as the one pulling 50 ma. I hooked up a single silicon solar cell (the type used for charging batteries) directly to a 0 to 1 ma meter. This is supposed to be a fairly linear power detector when hooked up like this. Out of the box the worst pen read 230 ua and the best 650 ua. Switching batteries around I could make any of them the worst and just about any of them the best. However, using a 'standard' set of batteries there still was a considerable difference between pens. So here's what I did: I hooked each of the pens to a variable power supply and ran the current up to 50 ma. At this point the 0-1 ma meter was against the pin! Even my best He-Ne laser will NOT pin this meter. Although I don't know the specs on the particular diode that these pens are using I have noticed that even the lowest power laser diodes are usually spec'd at around 55 ma. Also after playing around with laser diodes you kind of get a feeling as to how hard you can drive them before they destroy themselves, but I have to admit that I've zapped a few diodes (but no pens - yet!) playing around like this! I really need to find someone with a calibrated power meter but doing the best comparisons that I can I feel that at 55 ma (the highest current tried) these pens are putting out at least 5 mw possibly a bit more! I've had one going now for 24 hours and it shows no power creep nor gives any sign of quitting so I feel reasonably safe in operating it at this power level. By the way it took six volts to get this particular pen to this current level. Some of the others will do 50 ma at 4.5 volts. One other took almost 12 volts to achieve 50 ma. In each case after the high power experiment was over I returned the pen to it's original condition and checked power level. It was right where I started so it looks like no damage was done. It a laser diode is damaged by too much current you will know about it immediately! One other reason why there is so much variation in required voltage to achieve 50 ma is because these pens use an internal power regulating feedback circuit. As the voltage is run up the regulator tries to compensate by backing the current down. What should really be done here is to change the feedback resistors in the power regulator. However, after looking at the miniature construction involved I decided against this and just raised the voltage. WARNING: If you are going to try this, keep in mind that the current is what is important here. Just because I have six volts across my pen doesn't mean that yours will take this much. You might achieve 50 ma at 4.5 volts or less or it could take 12 volts so measure the current! This appears to be a fairly low impedance circuit. I say this because I noticed that the current was lower when using long test leads. So if your milliamp meter has a fair amount of resistance in it you might be advised to set the current a little on the low side for when you remove the test leads your current will go up. This also explains why there was such a variation among batteries even though all were new. (The internal resistance of the cell comes into play here.) Also if you intend to try this, do it before your sixty days are up! You figure out why and remember you didn't hear this from me !!! This isn't the final word on this. I intend to follow this up with some more research but I just wanted to get on here and let everyone know that these pens may turn out to be a better investment than I first thought! When I have more time I'm going to set each pen to the same current level, say 50 ma and compare power output. I have a feeling that at a constant current the output will be about the same from pen to pen. (I need something more than a 0-1 ma meter to do this. I prefer to NOT use a multimeter to do this as the internal resistance of the meter and the leads running to it affect the meter readings. Putting a resistor in series with the solar cell would make this less critical but it makes the system less linear.) If you intend to experiment find a silicon solar cell (Radio Shack sells one.) and a 0-1ma meter and make up a simple power meter so you know exactly what you have before starting and can compare it with any changes. Other than the variations associated with the internal resistance of the 0-1 ma meter this type of power level meter should produce repeatable results. John K3PGP@msn.com >From owner-laser Thu Mar 20 11:12:39 1997 Return-Path: Received: by berlioz.nsc.com (4.1/SMI-4.1) id AA03891; Thu, 20 Mar 97 11:12:39 PST Date: Thu, 20 Mar 97 18:45:42 UT From: "John Yurek" Message-Id: To: "Laser Reflector" Subject: More on the Damark Laser Pens Sender: owner-laser@berlioz.nsc.com Precedence: bulk I have detected some power creep on one diode running at 52 ma. Based on this I suggest that they be operated between 45 and 50 ma. Anything above this and you're living dangerously! I do have several however that seem happy at 55 ma., but since I noticed the above I have decided to not push my luck and am now operating all between 48 ma and 50 ma. I suggest anyone trying this do the same. You be judge based on the above data and my previous post! I don't feel like blowing one up to find the max current and sending it back to Damark! John K3PGP@msn.com >From owner-laser Thu Mar 20 13:30:56 1997 Return-Path: Received: by berlioz.nsc.com (4.1/SMI-4.1) id AA09690; Thu, 20 Mar 97 13:30:56 PST Date: Thu, 20 Mar 97 20:54:12 UT From: "John Yurek" Message-Id: To: "Laser Reflector" Subject: Laser Diode Current Sender: owner-laser@berlioz.nsc.com Precedence: bulk I ran across the following chart for NVG Adjustable Focus Laser Modules which are spec'd at 5 mw output: 670 nm 30-35 ma 660 nm 55-65 ma 650 nm 65-80 ma 640 nm 70-90 ma I found it interesting that the current goes up with increasing frequency. This may explain why the Damark 670 nm laser pens don't pull a lot of current as they come from the factory. I might be pushing them at 48 to 50 ma but until I find out exactly what diode is in these pens I won't know for sure. Be careful when comparing different wavelength laser diodes! They are different animals. Also when comparing visible laser diodes to IR diodes with simple power indicators like a silicon solar cell be aware that these cells (like many pin diodes) are much more sensitive to radiation in the IR range. John K3PGP@msn.com >From owner-laser Thu Mar 20 14:47:54 1997 Return-Path: Received: by berlioz.nsc.com (4.1/SMI-4.1) id AA13262; Thu, 20 Mar 97 14:47:54 PST Date: Thu, 20 Mar 97 22:21:27 UT From: "John Yurek" Message-Id: To: "Laser Reflector" Subject: PMTs Sender: owner-laser@berlioz.nsc.com Precedence: bulk Steve - WA6EJO: Richard - KD6BQ: I want to take this opportunity to thank both of you for looking up those PMTs for my friend. I pretty much agree with your observations about the sensitivity being way down at 670 nm. >looking at the cathode spectral response curve it looks like the cathode radiant >response is about 1mA/W at 650nm vs 85mA/W at its peak response about 420nm >I couldn't find any info on the 5563147. I hope that this is helpful info. >--Richard KD6BQ That's a pretty drastic decrease in sensitivity! Although I can't speak for this particular tube I have used PMTs with similar response curves and even though they were way down at 633 nm (He-Ne) I still found them vastly superior to any kind of solid state detector. Any comments ??? The reason why I'm asking, is a friend of mine located 193 of them !!! and at least one other source has popped up in the past day or so. (I don't have one to play with at the moment however and I'm not sure if I want any or not!) However, like many other people I'm struggling to understand specs like those above. I don't even have a complete understanding of how to interpret the specs on simple things like pin diodes. How does one use the spec sheets to compare sensitivity ratings on pin diodes, PMTs, etc. Several people have asked me this and although I have a basic idea of how to interpret them I'm far from an expert and I don't feel comfortable advising other people on something like this. Judging by the questions I'm getting I'm not alone. Anyone feel like writing a short explanation about what all these numbers mean and how to compare one detector to another and most importantly how to determine if a tube like the one above is still a worth while investment for use at 670 nm even though it's response is down at 670 nm and how much more/less sensitive will it be than a solid state detector like a pin diode. If I don't hear from anyone on this in the next couple of weeks, I intend to go the library and educate myself !!! I'll share anything that I learn here. PS - I've already warned my friend about the problem PMTs have with bright light! They can be damaged even when NOT powered up!!! If you see one laying out in the sunlight on a table at a hamfest, PASS IT BY !!! Although they will recover somewhat with time, usually permanent damage results. John K3PGP@msn.com >From owner-laser Thu Mar 20 14:37:36 1997 Return-Path: Received: by berlioz.nsc.com (4.1/SMI-4.1) id AA12711; Thu, 20 Mar 97 14:37:36 PST From: daveaa1a@ssih.com Date: Thu, 20 Mar 1997 17:12:27 -0500 Message-Id: <199703202212.RAA00412@ssih.com> Mime-Version: 1.0 Content-Type: text/plain Content-Transfer-Encoding: 7bit Subject: Laser Imagineering To: laser@berlioz.nsc.com X-Mailer: SPRY Mail Version: 04.00.06.17 Sender: owner-laser@berlioz.nsc.com Precedence: bulk Sometimes things drop out of nowhere.. Ever since John/K3PGP began spreading his fertile ideas around here concerning laser subcarriers, biasing etc. I have not had a quiet moment.. Well here is todays effort in a nutshell.. While doing some S/N tests on the new Subcarrier system, a thought came to mind.. A ready to go, off the shelf LASER receiver, SSB/CW/NBFM/DATA fairly high tech and plenty sensitive/selective... I use a IC-706 Icom transceiver for going out as a ships Sparks, as a I.F. for the microwave stuff and general all around shack rig.. Today I plugged a photo diode directly into the HF receiving SO-239 antenna jack, aimed the 40 hkz carrier from the 650nm laser into it and guess what?: I heard a good signal/carrier at 40 khz (the IC706 tunes from 30 khz up to 200 mhz.) True the Icom is fairly deaf at 40 khz so I made it up with block gain from the diode detector to the receiver.. Two stages of mpf-102 is very good. Full dead quiet way over S9 to s0 noise floor difference in signal... A very promising set-up for mobile/hilltopping..No lenses involved yet.. Now to see if I can get any RF out of the 706 at 40 khz.. If not then a mixer/osc and low pass filter will do it along with the modified pre-amp for auto-switching Rx/Tx as described in earlier message at 4 mhz.. In case the 650nm band is crowded and full of QRM, I can switch the input of the photodiode amp. over to a 3' whip and hear Navy/Cutler, Loran, PLC's, LOWFER, CFH-Halifax, European Broadcasts on 150-250khz band. Many Aircraft/Marine Beacons etc.. Watta Country !!!... 73 de daveaa1a >From owner-laser Thu Mar 20 18:50:37 1997 Return-Path: Received: by berlioz.nsc.com (4.1/SMI-4.1) id AA23967; Thu, 20 Mar 97 18:50:37 PST Message-Id: <199703210247.VAA09453@host-04.colby.edu> X-Sender: aballen@colby.edu X-Mailer: Windows Eudora Light Version 1.5.2 Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Date: Thu, 20 Mar 1997 21:48:01 -0500 To: "John Yurek" From: "Art Allen, KY1K" Subject: Re: PMTs Cc: laser@berlioz.nsc.com Sender: owner-laser@berlioz.nsc.com Precedence: bulk > >looking at the cathode spectral response curve it looks like the cathode >radiant > >response is about 1mA/W at 650nm vs 85mA/W at its peak response about 420nm This is WAY down, but is typical. Still, it will totally blow the doors off of any solid state detector. Keep this in mind if you ever decide to do wide bandwidth dx-ing (where you ned the bandwidth/gain product). > >The reason why I'm asking, is a friend of mine located 193 >of them !!! and at >least one other source has popped up in the past day or so. >(I don't have one >to play with at the moment however and I'm not sure if I want any or not!) If these unknown tubes that are found in this quan can be purchased cheaply-then your friend needs to do it. For a couple of bucks each, I would take a chance on an unknown tube that was used or a pull. Without knowing the history-I'd let the owner keep all 193 of them if he wanted much more than that for them! Anyway, if they can be purchased cheaply, then snap them up and break one open. The dynodes are easy to trace and the kathode is at one end and the plate is at the other. Trace out the internal wiring and fire it up with a voltage divider to test it. For our purposes, these 'house numbered' tubes might be good as gold-who needs specs if the price is right and if they function hi hi. > >However, like many other people I'm struggling to understand specs like those >above. I don't even have a complete understanding of how to interpret the >specs on simple things like pin diodes. Hey John, the Hamamatsu solid state optoelectronics catalog and the PMT catalogs have EXCELLENT info on this-its a real good place to start. Call Hamamatsu, they will send very nice catalogs for free-but they are top of the line products and you can't afford to buy from them hi hi. >PS - I've already warned my friend about the problem PMTs have with bright >light! They can be damaged even when NOT powered up!!! If you see one laying >out in the sunlight on a table at a hamfest, PASS IT BY !!! Although they >will recover somewhat with time, usually permanent damage results. > PASS IT BY if it is a PULL or USED if the selling price is more than 10 dollars (unless the seller is willing to guarantee or swap it if it doesn't function). If it doesn't have specs, its worth much less (IMHO). The damage done by bright light (even if the device is not powered up) is REAL. People who don't know this DAMAGE tubes unknowingly, then they try to sell them. BEWARE USED TUBES. >From owner-laser Thu Mar 20 20:07:04 1997 Return-Path: Received: by berlioz.nsc.com (4.1/SMI-4.1) id AA26888; Thu, 20 Mar 97 20:07:04 PST Date: Thu, 20 Mar 1997 23:06:25 -0500 (EST) Message-Id: <2.2.16.19970320232918.283f9b48@mail.snet.net> X-Sender: paulc@mail.snet.net X-Mailer: Windows Eudora Pro Version 2.2 (16) Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" To: laser@berlioz.nsc.com From: "Paul A. Cianciolo" Subject: APD's are a detector? Sender: owner-laser@berlioz.nsc.com Precedence: bulk Hello all, Anyone ever use an APD as a detector... I wonder what the results were I think these are better then the average photodetector? Are they more sensitive I have a couple that came of of a fiber optic link.. 73's PaulC KB1RP >From owner-laser Thu Mar 20 20:05:35 1997 Return-Path: Received: by berlioz.nsc.com (4.1/SMI-4.1) id AA26828; Thu, 20 Mar 97 20:05:35 PST Date: Fri, 21 Mar 97 03:59:52 UT From: "John Yurek" Message-Id: To: "Laser Reflector" Subject: PMT Info Sender: owner-laser@berlioz.nsc.com Precedence: bulk Art: >Hey John, the Hamamatsu solid state optoelectronics catalog and the PMT >catalogs have EXCELLENT info on this-its a real good place to start. Call >Hamamatsu, they will send very nice catalogs for free-but they are top of >the line products and you can't afford to buy from them hi hi. OK - I've been told by about a half dozen people to contact Hamamatsu. Only problem no one gave me a phone number, fax number or adr. (I'd prefer the fax number if they have one!) I've already learned that they don't appear to have a web site. What a shame! > >looking at the cathode spectral response curve it looks like the cathode > >response is about 1mA/W at 650nm vs 85mA/W at its peak response about 420nm >This is WAY down, but is typical. Still, it will totally blow the doors off >of any solid state detector. Keep this in mind if you ever decide to do wide >bandwidth dx-ing (where you ned the bandwidth/gain product). This has been my finding also but I didn't have specs for the tube I was using so I don't have a clue as to what it was supposed to do. But I still need some numbers or need to learn how to interpret the specs. So far I've seen pin diodes spec'd at -108 dB Nep. What kind of number can I plug into a path loss equation for a photo multiplier tube like this? Or better yet, how to I calculate this from the spec sheet? (I have my own ideas on this but everyone is asking me and I don't feel qualified to answer this, so for the benefit of everyone on here, lets hear from someone who knows for sure! Right now I'd even settle for someone that THINKS they know! How about a good guess ???) PS - Those that think they know everything are very annoying to those of us that do! Sure leaves me out :-^) John K3PGP@msn.com >From owner-laser Thu Mar 20 20:07:05 1997 Return-Path: Received: by berlioz.nsc.com (4.1/SMI-4.1) id AA26889; Thu, 20 Mar 97 20:07:05 PST Date: Thu, 20 Mar 1997 23:02:52 -0500 (EST) Message-Id: <2.2.16.19970320232544.269f7622@mail.snet.net> X-Sender: paulc@mail.snet.net X-Mailer: Windows Eudora Pro Version 2.2 (16) Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" To: laser@berlioz.nsc.com From: "Paul A. Cianciolo" Subject: Experiment with a CCD camera Sender: owner-laser@berlioz.nsc.com Precedence: bulk Hello Folk, I just thought I would throw in .02 cents on a experiment. I have a CCD surveillance camera that was donated to the "Cause" a year or so ago. It sees very well into the IR range.. My wood stove drives the camera crazy. Well I have a zoom lens that has the correct mount for this camera that is about 2.5" in Dia. I decided to screw it on and check out a sample IR LED I got from a manufacturer. While the big lens was on I decided to check out the local broadcast towers lights. 1 is 2 miles away and the other a strobe that I use for a beacon is 21 miles away. I worked for the station that owns the tower 21 miles away. The antenna on top of the 1000' tower is roughly 60' high. I can resolve the 2 individual beacons on the antenna. They are separated by about 1" on a tv screen that measures 10" top to bottom. they local lights on the towers 2 miles away swamp the CCD and I need to Iris way down if I focus on those. I can see lots of other lights on the horizon that seem to twinkle. The ones leading up to the top of the 1000' tower also twinkle. Very easy to see on the tv screen. The red tower lights I cannot see with just me eyes alone.. The camera sees them fine. No great revelations here I just thought it was interesting the sensetivity of the device even with the small lens. 73's PaulC KB1RP >From owner-laser Fri Mar 21 07:27:49 1997 Return-Path: Received: by berlioz.nsc.com (4.1/SMI-4.1) id AA14828; Fri, 21 Mar 97 07:27:49 PST From: daveaa1a@ssih.com Date: Fri, 21 Mar 1997 10:23:13 -0500 Message-Id: <199703211523.KAA03044@ssih.com> Mime-Version: 1.0 Content-Type: text/plain Content-Transfer-Encoding: 7bit Subject: Lenses To: laser@berlioz.nsc.com X-Mailer: SPRY Mail Version: 04.00.06.17 Sender: owner-laser@berlioz.nsc.com Precedence: bulk Gudday Brothers of the Light.. I just received part of a junked projection T.V. and one unit looks like a small periscope about 8" high and 6" diameter.. The input lense is 5.5 x 4.25" then sees a 90 degree mirror then goes through a 3.5" lense out the bottom.. A far away light source makes a nice pin point focus at the base.. It also has a variable focus.. After trying some remote laser diode light and placement of the detector at the base along with eyeballing other remote light point sources (NOT LASER) i find this unit will make a dandy receive antenna for a little shoe box transverter.. Mount a rifle 4x scope next to it and register the two, then put the diode laser transmitter next to that on the same box with the X/Y micrometers and that outta do it.. Keep America Humming, build something !! 73 de daveaa1a >From owner-laser Fri Mar 21 13:25:04 1997 Return-Path: Received: by berlioz.nsc.com (4.1/SMI-4.1) id AA27454; Fri, 21 Mar 97 13:25:04 PST Message-Id: <199703212113.QAA04231@host-04.colby.edu> X-Sender: aballen@colby.edu X-Mailer: Windows Eudora Light Version 1.5.2 Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Date: Fri, 21 Mar 1997 16:13:46 -0500 To: laser@berlioz.nsc.com From: "Art Allen, KY1K" Subject: current to voltage amp design? Sender: owner-laser@berlioz.nsc.com Precedence: bulk Hi everyone... Its me again- I have a PMT and some very low noise, low input current op amps for use in a PM tube current to voltage converter. I have excellent design info from the Hamamatsu catalog for a photodiode amp, but the PM tube catalog doesn't address this issue at all. For the photodiode amp, I used a 1 gigohm feedback resistor. But, I do not know what to use for the PM tube amp-presumably, it has alot more gain than the diode, so, it probably doesn't need as much feedback resistance. Does anyone have any idea what to use for a PMT? I want to have the best rx possible, strictly narrowband rx (20 khz bandwidth is FB). Suggestions? thanks, Art.... >From owner-laser Fri Mar 21 13:20:28 1997 Return-Path: Received: by berlioz.nsc.com (4.1/SMI-4.1) id AA27269; Fri, 21 Mar 97 13:20:28 PST Message-Id: <199703212107.QAA03956@host-04.colby.edu> X-Sender: aballen@colby.edu X-Mailer: Windows Eudora Light Version 1.5.2 Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Date: Fri, 21 Mar 1997 16:07:46 -0500 To: laser@berlioz.nsc.com From: "Art Allen, KY1K" Subject: flocking paper group purchase Sender: owner-laser@berlioz.nsc.com Precedence: bulk Hi everyone, I'm going to put together a serious light receiver (pmt and 4 inch glass lens). I will need flocking paper in order to minimize QRM from internal reflections in the scope tube. I will price it and get back to the group-if anyone would like to go in on a strictly cost basis, it does get quite a bit cheaper if purchased in quan. If you have any interest in flocking paper, let me know about how much you would need and I will look for a good deal based on the estimated quan. My wife is an astronomy major and KNOWS this stuff is like a night an day difference-it works. Let me know..Art, KY1K. >From owner-laser Fri Mar 21 19:16:41 1997 Return-Path: Received: by berlioz.nsc.com (4.1/SMI-4.1) id AA10920; Fri, 21 Mar 97 19:16:41 PST From: daveaa1a@ssih.com Date: Fri, 21 Mar 1997 22:13:20 -0500 Message-Id: <199703220313.WAA05520@ssih.com> Mime-Version: 1.0 Content-Type: text/plain Content-Transfer-Encoding: 7bit Subject: Re: flocking paper group purchase To: "Art Allen, KY1K" , laser@berlioz.nsc.com In-Reply-To: <199703212107.QAA03956@host-04.colby.edu> X-Mailer: SPRY Mail Version: 04.00.06.17 Sender: owner-laser@berlioz.nsc.com Precedence: bulk >I will need flocking paper in order to minimize QRM from internal What the flock is that?? >From owner-laser Fri Mar 21 20:15:09 1997 Return-Path: Received: by berlioz.nsc.com (4.1/SMI-4.1) id AA12814; Fri, 21 Mar 97 20:15:09 PST Message-Id: <199703220252.VAA53800@mime3.prodigy.com> X-Mailer: Prodigy Internet GW(v0.9beta) - ae01dm04sc03 From: DWNN13A@prodigy.com (MR JOHN T CAULEY JR.) Date: Fri, 21 Mar 1997 21:52:30, -0500 To: laser@berlioz.nsc.com Subject: Laser experimenters in DFW area? Sender: owner-laser@berlioz.nsc.com Precedence: bulk I have recently become interested in laser communications & am now working on my first (laser pointer) system. I would like to hear from any other folks in the Dallas/Ft. Worth area who are also doing this. John (kc5an) >From owner-laser Sat Mar 22 04:19:23 1997 Return-Path: Received: by berlioz.nsc.com (4.1/SMI-4.1) id AA25949; Sat, 22 Mar 97 04:19:23 PST Message-Id: <199703221218.HAA29399@host-04.colby.edu> X-Sender: aballen@colby.edu X-Mailer: Windows Eudora Light Version 1.5.2 Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Date: Sat, 22 Mar 1997 07:18:05 -0500 To: laser@berlioz.nsc.com From: "Art Allen, KY1K" Subject: flocking paper Sender: owner-laser@berlioz.nsc.com Precedence: bulk Several have asked 'what the flock is flocking paper?'. Flocking papaer is like a roach motel-the light goes in, but it never comes back out. It is a VERY LOW reflection black paper used by telescope makers and electronic instrumentation makers. For those who need protection from outside light sources: First line of defense-put a light shield, an extension, over the end of the lens housing to minimize light pickup from outside the len's field of view. But, if the interfering light is within the len's field of view, the only way to stop is is to make sure that it never reaches the detector.... Of course, your lens will probably make sure the light source does not fall directly on the detector by focusing it on a different area. But, if the area where the light falls just ends up reflecting the light, it bounces around and some of it ends up on the detector. Flat black paint on a smooth surface doesn't absorb light well, I've tried it. I've also tried various paints and paper types, its better, but not really as good as it should be. Flocking paper is made for this purpose-you can look at the sun's reflection off its surface, and it barely shows anything. Try that with plain flat black paint applied to a smooth surface! I've also learned recently of a SPECIAL flat black paint which is applied to a 'specialy prepared surface'-its used in movie theaters and other similar places. I'm checking on that as an alternative to flocking paper. For those with photo diode rx working local's, it probably isn't needed unless they are using big len's for light gathering. But, for those working with PM tubes in longer distance paths, it should help alot. For those that doubt that it is necessary, hold your flat black painted surface under a bright light and look at the reflection from it. GL...Art, KY1K. >From owner-laser Sat Mar 22 07:30:55 1997 Return-Path: Received: by berlioz.nsc.com (4.1/SMI-4.1) id AA00705; Sat, 22 Mar 97 07:30:55 PST From: sjnoll@ix.netcom.com Date: Sat, 22 Mar 1997 09:26:27 -0600 (CST) Message-Id: <199703221526.JAA02637@dfw-ix7.ix.netcom.com> Mime-Version: 1.0 Content-Type: text/plain Content-Transfer-Encoding: 7bit Subject: Black Flocking Paper To: laser@berlioz.nsc.com X-Mailer: SPRY Mail Version: 04.10.06.22 Sender: owner-laser@berlioz.nsc.com Precedence: bulk I buy this stuff at work for lining electro-optic test fixtures. Get it from Edmund. 20" x 30" adhesive-backed $8.50 27" x 36" non-adhesive $8.00 73, Steve J. Noll | Ventura CA | WA6EJO | sjnoll@ix.netcom.com | http://www.netcom.com/~sjnoll/usedequip.html | http://www.netcom.com/~sjnoll/peltier.html >From owner-laser Sat Mar 22 07:54:35 1997 Return-Path: Received: by berlioz.nsc.com (4.1/SMI-4.1) id AA01097; Sat, 22 Mar 97 07:54:35 PST From: sjnoll@ix.netcom.com Date: Sat, 22 Mar 1997 09:49:50 -0600 (CST) Message-Id: <199703221549.JAA17996@dfw-ix2.ix.netcom.com> Mime-Version: 1.0 Content-Type: text/plain Content-Transfer-Encoding: 7bit Subject: Flock what? To: laser@berlioz.nsc.com X-Mailer: SPRY Mail Version: 04.10.06.22 Sender: owner-laser@berlioz.nsc.com Precedence: bulk Black flocking paper is like jet-black velour on a paper backing. It is extremely black, more so than the average flat black paint. You can use this to line things like telescope tubes where you don't want stray light bouncing around in the wrong places. If you build your lightwave receiver by placing a lens in a pipe, lining the pipe will reduce interference from, for example, streetlight light that enters the receiver at an angle. Otherwise some of that light would bounce off the sides of the tube and make its way to your detector. If you operate so that there are no nearby sources of interfering light then the use of this black lining is questionable. For example, at work I use it to line photometric microscope tubes - microscopes that we use to focus laser spots onto detectors for testing. The great light absorbing properties reduce unwanted light reflections. I use it to line the insides of lids of fixtures used to measure detector dark current. The stuff is easy to get dirty. Also, the adhesive on Edmund's adhesive-backed version can be very sticky & gooey. 73, Steve J. Noll | Ventura CA | WA6EJO | sjnoll@ix.netcom.com | http://www.netcom.com/~sjnoll/usedequip.html | http://www.netcom.com/~sjnoll/peltier.html >From owner-laser Sat Mar 22 19:27:30 1997 Return-Path: Received: by berlioz.nsc.com (4.1/SMI-4.1) id AA19280; Sat, 22 Mar 97 19:27:30 PST From: Kb8tej1@aol.com Date: Sat, 22 Mar 1997 22:24:42 -0500 (EST) Message-Id: <970322222441_1551555550@emout06.mail.aol.com> To: laser@berlioz.nsc.com Subject: Enlarger lenses Sender: owner-laser@berlioz.nsc.com Precedence: bulk Just finished the Ramsey IR kit(don't laugh, at lest it works the first time, don't even ask abt my hmbrew 15 meter receiver) rummaging around in my build yr own starship junquebox I found several 4" 5" and 6" plano/convex enlarger lenses (Graflex and others-I bet the folks on the camera collector lists will cringe with what I did with them!) they have abt 5" to 6" F/L and using an eypiece show a marked "Fish eye" effect. My question is this they obviously have some significant light gathering power and a "Can" type scope would be would be very compact. Would the "Fisheye" effect make for a somewhat easier target to hit due to the wider field of view? Does a wider field of view come at the expense of Gain, I'm not a optical expert but most "fisheye" lenses are relativley "Fast" and I presume(risky thing that!) that translates to gain? Also what makes a good, and cheap, IR filter? In regardes to Flocking, spraying a heavy coat of flat balck enamel and dusting on flocking, from an art supply store, makes an incredably black and light absorbing surface ( old stage magician's trick) a salt shaker makes a great "Dusting" tool. A blast from a freon (OOPS Politically and ecologicly incorrect!!!) air supply will easily remove the excess. 73 and tnx for any help Rob PS If this works will be willing to trade a lens for a Laser diode. >From owner-laser Sat Mar 22 20:19:54 1997 Return-Path: Received: by berlioz.nsc.com (4.1/SMI-4.1) id AA20517; Sat, 22 Mar 97 20:19:54 PST Message-Id: <3.0.1.16.19970322214441.2afff010@edge.net> X-Sender: rmidgett@edge.net X-Mailer: Windows Eudora Pro Version 3.0.1 (16) Date: Sat, 22 Mar 1997 21:44:41 To: "Art Allen, KY1K" , laser@berlioz.nsc.com From: "Robin E. Midgett" Subject: Re: optical biasing.... In-Reply-To: <199703081307.IAA09911@host-04.colby.edu> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Sender: owner-laser@berlioz.nsc.com Precedence: bulk Hello Art & Reflector, I am a newbie to the "photon heads" group & am very much interested in experimenting with laser communications, particularly in the VHF/UHF contests. 2 questions: Is 1km still the suggested minimum distance between operators for the contests? What is a mrad, & what is its significance to laser communications. I presume it is a measure of the laser wavelength....... BTW, one more (for a total of three!) how does one (an amateur) measure the power output of a laser? At 08:07 AM 3/8/97 -0500, Art Allen, KY1K wrote: >I was interested in seeing IF this marginal setup and my QRP HE-NE would >meet the 1 km suggested minimum in the vhf contest rules. > >Incidently, I found that these simple RX's COULD hear my 1 mw @ 2.2 mrad >laser at a distance of 1 mile (without the use of light gathering lenses). >We used some of these inexpensive RX setups to make some short range laser >Q's during a couple of the vhf contests later. > >73 and GL..Art... 73, Robin KB4IDC Your e-mail returned due to insufficient voltage. >From owner-laser Sun Mar 23 03:14:47 1997 Return-Path: Received: by berlioz.nsc.com (4.1/SMI-4.1) id AA29187; Sun, 23 Mar 97 03:14:47 PST Message-Id: <199703231113.GAA01604@host-04.colby.edu> X-Sender: aballen@colby.edu X-Mailer: Windows Eudora Light Version 1.5.2 Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Date: Sun, 23 Mar 1997 06:13:37 -0500 To: laser@berlioz.nsc.com From: "Art Allen, KY1K" Subject: Re: optical biasing.... Cc: "Robin E. Midgett" Sender: owner-laser@berlioz.nsc.com Precedence: bulk At 09:44 PM 03/22/1997, you wrote: >Hello Art & Reflector, >I am a newbie to the "photon heads" group & am very much interested in >experimenting with laser communications, particularly in the VHF/UHF >contests. 2 questions: > >Is 1km still the suggested minimum distance between operators for the >contests? > 1km is still the rule. It does not just apply to laser comm tho. It applies to all VHF/UHF and microwaves and higher. Its designed to prevent mass manufacture of qso's-basically, if the SYSTEM isn't capable of 1 km, then they don't consider it a real radio! Incidently, its not 'suggested minimum distance between operators'... The operators can be a few feet or 10's of feet apart, and thats fine by the rules (makes liason between the ends of the path easy hi hi). What the rule means is that the SYSTEM should be capable of spanning a 1 km distance! So, if you are dealing with simple tx and rx's and want to make a few qso's during the contest, all you need to do is to set up the gear once and confirm that it can work the 1 km distance.. After you know the simple gear is capable of spanning the distance, then you can use it to make contacts that are closer. My comments below are meant to make beginners aware that a simple phototransistor/741 op amp without a light gathering lens/1 mw laser DO MEET the 1 km requirement. >What is a mrad, & what is its significance to laser communications. I >presume it is a measure of the laser wavelength....... > MRAD = milliradian. It means 1/1000 of a radian. There are 2 * pi radians per 360 degrees, so a radian is 2(3.14159) divided into 360 (360/6.28). It comes out to about 57 degrees. So, a 'mrad' equals (about) .057 degrees. Its used by us to quantify divergence, which is how much the laser spreads out once it leaves the source. I'm not sure why they use those units, but in practical terms it means this: If a laser is 1 foot wide at 1000 feet, then it is 1 mrad. If a laser is 10 feet wide at 1000 feet, then it is 10 mrad. If a laser is 10 meters wide at 1000 meters, then it is 10 mrad. If a laser is 10 miles wide at 1000 miles, then it is 10 mrad. So, by using milliradians, it makes the numbers easier to work with and calculate in your head. Thats probably why we use those units. >BTW, one more (for a total of three!) how does one (an amateur) measure the >power output of a laser? > Well, basically, most of us DONT! We take a 5 mw tube, and assume its between 3 and 5! Or, we take a laser diode that is rated for XX mw @ such and such drive level, and assume its about that power level (+/-). In actual practice, a power level that is only half of your guestimate is only going to be 3 db down at the RX, so actual power level doesn't really need to be PRECISELY known. What's really more important is to know the RX sensitivity! And thats no small feat. You can loose many many db in a SYSTEM by running a crappy RX. Again, most of us don't have the gear to actually QUANTIFY RX sensitivity, but I wanted you to realize that the RX is a much bigger variable ththan the TX is! Incidently, for an inexpensive and fairly high performance RX system, the Burr-Brown combo photodiode/op amp ass'ys are the way to go! When you buy the whole chip, THEY rate the sensitivity of the RX! It takes alot of guesswork out of the calculations, because you have a real good idea of the sensitivity of the RX! Hey Robin, glad to have you aboard. Im sure some of these other silver tounged devils on the list will have other comments too. Drop a line to the list if there are other questions, and make sure to check out the laser comm www page too. GL..Art, KY1K. >At 08:07 AM 3/8/97 -0500, Art Allen, KY1K wrote: > >>I was interested in seeing IF this marginal setup and my QRP HE-NE would >>meet the 1 km suggested minimum in the vhf contest rules. >> >>Incidently, I found that these simple RX's COULD hear my 1 mw @ 2.2 mrad >>laser at a distance of 1 mile (without the use of light gathering lenses). >>We used some of these inexpensive RX setups to make some short range laser >>Q's during a couple of the vhf contests later. >> >>73 and GL..Art... > >73, Robin KB4IDC > >Your e-mail returned due to insufficient voltage. > > >From owner-laser Sun Mar 23 04:09:32 1997 Return-Path: Received: by berlioz.nsc.com (4.1/SMI-4.1) id AA00252; Sun, 23 Mar 97 04:09:32 PST Message-Id: <199703231207.HAA02500@host-04.colby.edu> X-Sender: aballen@colby.edu X-Mailer: Windows Eudora Light Version 1.5.2 Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Date: Sun, 23 Mar 1997 07:08:04 -0500 To: laser@berlioz.nsc.com From: "Art Allen, KY1K" Subject: Re: Enlarger lenses Cc: Kb8tej1@aol.com Sender: owner-laser@berlioz.nsc.com Precedence: bulk At 10:24 PM 03/22/1997 -0500, you wrote: >Just finished the Ramsey IR kit(don't laugh, at lest it works the first time, We all start somewhere-I bet there isn't a single soul laughing! >rummaging around in my build >yr own starship junquebox I found several 4" 5" and 6" plano/convex enlarger >lenses (Graflex and others-I bet the folks on the camera collector lists will >cringe with what I did with them!) they have abt 5" to 6" F/L and using an >eypiece show a marked "Fish eye" effect. My question is this they obviously >have some significant light gathering power and a "Can" type scope would be >would be very compact. Would the "Fisheye" effect make for a somewhat easier >target to hit due to the wider field of view? Does a wider field of view come >at the expense of Gain, I'm not a optical expert but most "fisheye" lenses >are relativley "Fast" and I presume(risky thing that!) that translates to >gain? Hey, those 6 inch lenses are GOOD AS GOLD! There was a discussion in the December 'Sky and Telescope' mag regarding eyepiece selection-it was very enlightening. It boiled down to 'the highest mag power is not always the best policy' when it comes to light gathering! If you have a 6 inch plano-convex with a 6 inch focal length, don't use an eyepiece at all!!! The eyepiece will make the field of view narrower, but you don't need it unless you are building something that you are looking thru with your eye. I suggest you plant the RX at the focal point. The lens will have a wide field of VIEW, but only the light that the lens is aimed at will fall on the detector! Light from QRM sources will focus to the left/right/above or below the RX. Obviously, to get the most out of this system, you need to be carefull about reflected light, when the QRM falls NEAR the RX active element, you want to make sure that it doesn't bounce around hi hi. Also, you may need to restrict the active area of the rx-if it is too large! You don't want QRM+desired signal to hit the RX element, you only want 'desired signal'!! Experiment with the SIZE of the active area! With high quality glass lens, you can use fairly small active area devices because the optics are precise. With plastic or frensel lenses, you need a much larger active area device, because they can't focus well enuff to get all the light from the target to hit the RX active element. >Also what makes a good, and cheap, IR filter? Cheep? Cheep is a relative term. Optical quality needed? Bandwidth needed? Minimum insertion loss acceptable? Bandpass, or lowpass/high pass? Best IR filter (for blocking IR) is a 'cold miror', used in that over head projector that you got the lens from. Did you see a mirror that tinted 'tinted'? That's the one! Very low loss and very high quality optically and its a low pass filter. It might also be a flat piece of 'tinted glass' that is optically clear too (except for the tinting). For low cost/high insertion loss, you can use unexposed film (the black part from a negative). It blocks visible, but allows IR to pass. I've not used this myself, let the buyer beware. There are also a wide variety of filters for photographic work. Check out your local camera shop. >In regardes to Flocking, >spraying a heavy coat of flat balck enamel and dusting on flocking, from an >art supply store, makes an incredably black and light absorbing surface ( old >stage magician's trick) a >salt shaker makes a great "Dusting" tool. A blast from a freon (OOPS >Politically and >ecologicly incorrect!!!) air supply will easily remove the excess. Rob, I actually tried this. The best 'dust' I could find was from my vacuum cleaner bag. But, I could NEVER make it stable enuff to withstand shaking and vibration, which is inevitable. The dust helped alot (when compared to just the bare flat black). But, how can you prevent the dust from shaking loose and ending up on your expensive PM tube face or photodiode? I tried clear laquer and some varying thicknesses of flat black spray paint as a binder for the dust, but that made the surface reflective again! I also tried varying ammounts of air volume to remove the 'excess'. I went all the way up to the point where I blew the paint off the surface...but, no matter what I tried, I could never make anything that was mechanicly stable. Did I miss something? >PS If this works will be willing to trade a lens >for a Laser diode. > I'm about to put together a 4 inch lens and PM tube. I would love to have a 5 or 6 inch glass lens tho! If I had a laser diode, I'd jump on your trade proposal in a minute! Good luck and GOOD DX...Art... >From owner-laser Sun Mar 23 04:33:27 1997 Return-Path: Received: by berlioz.nsc.com (4.1/SMI-4.1) id AA00903; Sun, 23 Mar 97 04:33:27 PST From: daveaa1a@ssih.com Date: Sun, 23 Mar 1997 07:31:23 -0500 Message-Id: <199703231231.HAA10217@ssih.com> Mime-Version: 1.0 Content-Type: text/plain Content-Transfer-Encoding: 7bit Subject: Re: Enlarger lenses To: Kb8tej1@aol.com Cc: laser@berlioz.nsc.com In-Reply-To: <970322222441_1551555550@emout06.mail.aol.com> X-Mailer: SPRY Mail Version: 04.00.06.17 Sender: owner-laser@berlioz.nsc.com Precedence: bulk >lenses (Graflex and others-I bet the folks on the camera collector lists will >cringe with what I did with them!) they have abt 5" to 6" F/L and using an >eypiece show a marked "Fish eye" effect. Hi Rob, Dunno about the fish eye lenses.. Think maybe a smaller field of view will see less ambient/unwanted light.. A 4" convex from Edmunds Scientific does well for me and a periscope lense off a junked TV seems good.. I thought the best i could come up with would be a Telephoto lense and a junked Single lense reflex camera might make a neat receiver.. You might be surprised at the range of the Ramsey kit if you add a lense.. Thanks for the good idea on flocking.. 73 de daveaa1a >From owner-laser Sun Mar 23 08:07:57 1997 Return-Path: Received: by berlioz.nsc.com (4.1/SMI-4.1) id AA05723; Sun, 23 Mar 97 08:07:57 PST From: Kb8tej1@aol.com Date: Sun, 23 Mar 1997 11:07:47 -0500 (EST) Message-Id: <970323110746_1715896056@emout16.mail.aol.com> To: aballen@colby.edu, laser@berlioz.nsc.com Subject: Flocking, was Enlarger Lenses Sender: owner-laser@berlioz.nsc.com Precedence: bulk Art, just saw a post on one of the ATM pages that advocated the use of flat black velvet for covering light stops in Newtonian telescopes, may be something there, closer than Edmund Sci. and probably cheaper at the local piece goods shop. Rob >From owner-laser Sun Mar 23 09:32:50 1997 Return-Path: Received: by berlioz.nsc.com (4.1/SMI-4.1) id AA07935; Sun, 23 Mar 97 09:32:50 PST Message-Id: <199703231731.MAA10118@host-04.colby.edu> X-Sender: aballen@colby.edu X-Mailer: Windows Eudora Light Version 1.5.2 Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Date: Sun, 23 Mar 1997 12:31:15 -0500 To: laser@berlioz.nsc.com From: "Art Allen, KY1K" Subject: Re: Flocking, was Enlarger Lenses Sender: owner-laser@berlioz.nsc.com Precedence: bulk At 11:07 AM 03/23/1997 -0500, you wrote: >Art, just saw a post on one of the ATM pages that advocated the use of flat >black velvet for covering light stops in Newtonian telescopes, may be >something there, closer than Edmund Sci. and probably cheaper at the local >piece goods shop. Rob > > OK, I was going to check out 'black felt' at my local fabric salon-Ill look for black velvet while Im there. Thanks so much for the tip... Art, KY1K. >From owner-laser Sun Mar 23 16:02:21 1997 Return-Path: Received: by berlioz.nsc.com (4.1/SMI-4.1) id AA17974; Sun, 23 Mar 97 16:02:21 PST Date: Sun, 23 Mar 1997 18:59:10 -0500 (EST) Message-Id: <2.2.16.19970323192130.2b57a87c@mail.snet.net> X-Sender: paulc@mail.snet.net X-Mailer: Windows Eudora Pro Version 2.2 (16) Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" To: laser@berlioz.nsc.com From: "Paul A. Cianciolo" Subject: Laser tube trouble? Sender: owner-laser@berlioz.nsc.com Precedence: bulk Hello Folks, I sold a laser tube to a friend so he could perform some communication experiments. A few days after the sale the tube still glows but does not give any output. The intensity of the tube inside is still the same as before but no lasing. The output dropped over a period of a couple hours. Does anyone know if this is anormal failure mode for a 5-7 mw tube? Current and voltage tot the tube are still the same as when running. Any help would be appreciated. Thanks in advance 73's PaulC KB1RP >From owner-laser Sun Mar 23 16:48:10 1997 Return-Path: Received: by berlioz.nsc.com (4.1/SMI-4.1) id AA19227; Sun, 23 Mar 97 16:48:10 PST From: daveaa1a@ssih.com Date: Sun, 23 Mar 1997 19:45:51 -0500 Message-Id: <199703240045.TAA12419@ssih.com> Mime-Version: 1.0 Content-Type: text/plain Content-Transfer-Encoding: 7bit Subject: Noise Figure ?? To: laser@berlioz.nsc.com X-Mailer: SPRY Mail Version: 04.00.06.17 Sender: owner-laser@berlioz.nsc.com Precedence: bulk Gudday, Just pointed the base band rig at the full moon and see 4 db white noise above normal background noise.. Hale-Bopp, nil Serious, nil Mars, nil Bellatrix, nil How deaf does that make me?? What is the noise figure?? 73 de daveaa1a >From owner-laser Mon Mar 24 10:52:20 1997 Return-Path: Received: by berlioz.nsc.com (4.1/SMI-4.1) id AA19609; Mon, 24 Mar 97 10:52:20 PST Date: Mon, 24 Mar 1997 12:30:52 -0600 (CST) Message-Id: <199703241830.MAA01390@firefly.prairienet.org> From: w9sz@prairienet.org (Zack Widup) To: laser@berlioz.nsc.com Subject: Dead laser Reply-To: w9sz@prairienet.org Sender: owner-laser@berlioz.nsc.com Precedence: bulk > >Hello Folks, > >I sold a laser tube to a friend so he could perform some communication >experiments. A few days after the sale the tube still glows but does not >give any output. The intensity of the tube inside is still the same as >before but no lasing. The output dropped over a period of a couple hours. > >Does anyone know if this is anormal failure mode for a 5-7 mw tube? > >Current and voltage tot the tube are still the same as when running. > >Any help would be appreciated. > >Thanks in advance > > >73's >PaulC KB1RP > > Hi Paul, Yes, I had this happen to one also. I was told that the helium actually slowly diffuses out through the glass and eventually reaches a low enough level that you're left with a big neon bulb :-( Zack W9SZ -- >From owner-laser Mon Mar 24 16:05:09 1997 Return-Path: Received: by berlioz.nsc.com (4.1/SMI-4.1) id AA01796; Mon, 24 Mar 97 16:05:09 PST Date: Mon, 24 Mar 1997 16:18:16 -0700 From: c1040@azfms.com (Rusty Carruth) Message-Id: <9703242318.AA04274@fmsserv99.azfms.com> To: laser@berlioz.nsc.com, w9sz@prairienet.org Subject: Re: Dead laser X-Sun-Charset: US-ASCII Sender: owner-laser@berlioz.nsc.com Precedence: bulk > > I was told that the helium actually slowly diffuses out through the glass > and eventually reaches a low enough level that you're left with a big > neon bulb :-( > ASSUMING that this is the problem you are having - it is possible to re-load them, but cost of doing so may be more than cost of replacement laser... rusty >From owner-laser Mon Mar 24 18:23:16 1997 Return-Path: Received: by berlioz.nsc.com (4.1/SMI-4.1) id AA07608; Mon, 24 Mar 97 18:23:16 PST Date: Mon, 24 Mar 1997 21:06:14 -0500 (EST) Message-Id: <2.2.16.19970324212820.27ef29bc@mail.snet.net> X-Sender: paulc@mail.snet.net X-Mailer: Windows Eudora Pro Version 2.2 (16) Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" To: laser@berlioz.nsc.com From: "Paul A. Cianciolo" Subject: Atmospheric attenuation formula Sender: owner-laser@berlioz.nsc.com Precedence: bulk Hello Folks, Can anyone post(easily I dont want to cause some to type the whole thing in) the atmospheric attenuation formula. I have a friend at work who will put into a spreadsheet for me so different factors can be entered and modeled.. sorta... Thank You 73's PaulC KB1RP >From owner-laser Mon Mar 24 19:26:00 1997 Return-Path: Received: by berlioz.nsc.com (4.1/SMI-4.1) id AA09942; Mon, 24 Mar 97 19:26:00 PST Message-Id: <199703250323.WAA21337@host-04.colby.edu> X-Sender: aballen@colby.edu X-Mailer: Windows Eudora Light Version 1.5.2 Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Date: Mon, 24 Mar 1997 22:23:33 -0500 To: laser@berlioz.nsc.com From: "Art Allen, KY1K" Subject: Re: Dead laser Sender: owner-laser@berlioz.nsc.com Precedence: bulk At 12:30 PM 03/24/1997 -0600, you wrote: > > >> >>Hello Folks, >> >>I sold a laser tube to a friend so he could perform some communication >>experiments. A few days after the sale the tube still glows but does not >>give any output. The intensity of the tube inside is still the same as >>before but no lasing. The output dropped over a period of a couple hours. >> >>Does anyone know if this is anormal failure mode for a 5-7 mw tube? >> >>Current and voltage tot the tube are still the same as when running. >> >>Any help would be appreciated. >> >>Thanks in advance >> >> >>73's >>PaulC KB1RP >> >> > >Hi Paul, > >Yes, I had this happen to one also. > >I was told that the helium actually slowly diffuses out through the glass >and eventually reaches a low enough level that you're left with a big >neon bulb :-( > >Zack W9SZ > >-- > > I'm not so sure that this is the problem. If it was lack of helium, wouldn't there still be some sort of reduced beam output because of the helium neon plasma? Since the tube is still starting and appears to be operating, I would suspect one of the mirrors has been bumped or has shaken loose. If the problem is caused by helium depletion, the tube can be restored easily and cheaply. Fortunately, neon is a bigger molecule and does not escape from the tube. Helium is a small molecule and it's escape is inevitable. Since the tube is operated at a pressure lower than atmospheric pressure, oxygen and nitrogen tend to leak INTO the tube-but not much-because those molecules are large too. So, putting a very small ammount of helium into the tube is EASY. Pressurize the tube at 1 psia in a helium atmosphere for an hour or so, then RETEST. Repeat until the tube lights. DO NOT overfill the tube, it will not work if there is too much helium. If you have a relative power meter, you can repeat the filling procedure till the output power peaks. A commonly accepted method of replenishing the helium supply is to put the tube in a balloon, then get it filled with helium. Thats all it takes- You can use industrial grade helium-hi purity gas isn't necessary because the contaminates mixed with helium are too large to force their way INTO the tube. The above info assumes that the mirrors aren't damaged. Enjoy...Art, KY1K. >From owner-laser Mon Mar 24 23:20:35 1997 Return-Path: Received: by berlioz.nsc.com (4.1/SMI-4.1) id AA17469; Mon, 24 Mar 97 23:20:35 PST Message-Id: <9703250716.AA15414@omnigroup.com> Content-Type: text/plain Mime-Version: 1.0 (NeXT Mail 4.1mach v148) In-Reply-To: <199703241830.MAA01390@firefly.prairienet.org> X-Nextstep-Mailer: Mail 3.3 (Enhance 1.3) From: William Lewis Date: Mon, 24 Mar 97 23:17:12 -0800 To: laser@berlioz.nsc.com Subject: Re: Dead laser References: <199703241830.MAA01390@firefly.prairienet.org> Sender: owner-laser@berlioz.nsc.com Precedence: bulk ISTR that it will slowly damage the tube to run it with reverse polarity. I'm a little unclear on the actual mechanism; I think it damages one of the electrodes by overheating. >From owner-laser Tue Mar 25 01:01:29 1997 Return-Path: Received: by berlioz.nsc.com (4.1/SMI-4.1) id AA21378; Tue, 25 Mar 97 01:01:29 PST Date: Tue, 25 Mar 97 08:03:24 UT From: "John Yurek" Message-Id: To: "Laser Reflector" Subject: Re: Dead laser Sender: owner-laser@berlioz.nsc.com Precedence: bulk > >Hello Folks, > >I sold a laser tube to a friend so he could perform some communication >experiments. A few days after the sale the tube still glows but does not >give any output. The intensity of the tube inside is still the same as >before but no lasing. The output dropped over a period of a couple hours. > >Does anyone know if this is anormal failure mode for a 5-7 mw tube? > >Current and voltage tot the tube are still the same as when running. > >Any help would be appreciated. > >Thanks in advance > > >73's >PaulC KB1RP > > ----- Paul: Unfortunately I think just about all of us who have used He-Ne lasers have had this happen at one time or another. However, I had a couple of tubes that would do this only when the temperature was warm. In this case 'warm' could even mean room temperature! These particular laser tubes could be stuck in the freezer for a few minutes and when taken out would run for a couple of hours, then the same thing would happen all over again. (No I didn't put the power supply in the freezer, just the tube so whatever was going on had nothing to do with the power supply.) In an air conditioned room they would also run continuously, or out in the winter air. Taking them outside on a hot summer day would cause them to fail in a few seconds, that's if they even started. In call cases the inside of the tube lit up normally and voltage & current was normal but there was no output. If a white piece of paper was held immediately in front of the exit mirror I could see a faint BLUE glow with a slight hint of pink/orange! I just assumed that the above meant that the tubes were low on helium. I've never seen this effect documented so I'm not sure. I'd be curious to see if sticking the tube that you sold in the freezer for a few hours revives it. However, this is only a temporary cure and assumes that your tube has the same ailment that mine had. John K3PGP@msn.com >From owner-laser Tue Mar 25 00:54:31 1997 Return-Path: Received: by berlioz.nsc.com (4.1/SMI-4.1) id AA21104; Tue, 25 Mar 97 00:54:31 PST Message-Id: <199703250129.UAC77640@mime3.prodigy.com> X-Mailer: Prodigy Internet GW(v0.9beta) - ae01dm04sc03 From: DWNN13A@prodigy.com (MR JOHN T CAULEY JR.) Date: Mon, 24 Mar 1997 20:29:33, -0500 To: laser@berlioz.nsc.com Subject: back-to-Kent, WA5Vjb, on laser in DFW Sender: owner-laser@berlioz.nsc.com Precedence: bulk >Hello John: >There are about a dozen Laser communications systems in the >Dallas Area. We are all members of the North Texas Microwave Society and use them for contest contacts during the VHF Contests. >Most of use a HeNe modulated by passing the beam through a >muffin fan. A solenoid holds a piece of metal blocking the beam, then >we use a CW key on the solenoid to send CW. >The receivers are PaveWay Bomb seekers into Radio Shack >"Telephone Monitor Amplifiers" Although a good size solar >cell also works well. The range equations all fall back to >capture area. So a 4" lens onto a photo transistor, and a >4" solar cell all have the same range. (And one is much >easier to point!!) >We also have several systems built around CD parts from >Tandy Surplus. The CD guts have both the Laser and the >detector in one assembly. >73's Kent WA5VJB Thanks for your reply, Kent. As I mentioned in my e-mail reply, I'm in NTMS & will chat with you at the next meeting. I have only been on this laser stuff for about a month now, so there is LOTS to learn. I have learned most of what i know so far from the messages on this "reflector" (MANY THANKS TO THE SPONSOR(S) !! I have a "prototype" ligt pen transceiver operating, & plan to use what I learn from it for an impproved version. It is AM voice, but I can add MCW..... hopefully then be compatible with the choppered HeNe ones used by the club. tnx es 73 John kc5an >From owner-laser Tue Mar 25 08:30:24 1997 Return-Path: Received: by berlioz.nsc.com (4.1/SMI-4.1) id AA04265; Tue, 25 Mar 97 08:30:24 PST From: Kb8tej1@aol.com Date: Tue, 25 Mar 1997 11:25:09 -0500 (EST) Message-Id: <970325112508_281370391@emout17.mail.aol.com> To: laser@berlioz.nsc.com Subject: bad photodiode/Burr-Brown Combo Sender: owner-laser@berlioz.nsc.com Precedence: bulk Discovered the most sensative area of my photodiode in my Ramsey kit receiver was almost 90 deg away from the axis suggested by the dome surface, is this a common problem?? the range without lenses was less than a foot along the "suggested " axis, some improvment , but not much with some very large lenses. Replacement was promised by Ramsey. What exactly is the "Burr-Brown combo" and who is the vendor? Tnx Rob >From owner-laser Tue Mar 25 10:51:00 1997 Return-Path: Received: by berlioz.nsc.com (4.1/SMI-4.1) id AA11229; Tue, 25 Mar 97 10:51:00 PST Date: Tue, 25 Mar 1997 10:34:08 -0800 (PST) From: Clifford Buttschardt To: "Art Allen, KY1K" Cc: laser@berlioz.nsc.com Subject: Re: Dead laser In-Reply-To: <199703250323.WAA21337@host-04.colby.edu> Message-Id: Mime-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: owner-laser@berlioz.nsc.com Precedence: bulk Yes, I have heard exactly this same advice from a guy that worked for Spectra Physics in Mountain View, CA. I suspect this is good advice! Cliff Buttschardt K7RR On Mon, 24 Mar 1997, Art Allen, KY1K wrote: > At 12:30 PM 03/24/1997 -0600, you wrote: > > > > > >> > >>Hello Folks, > >> > >>I sold a laser tube to a friend so he could perform some communication > >>experiments. A few days after the sale the tube still glows but does not > >>give any output. The intensity of the tube inside is still the same as > >>before but no lasing. The output dropped over a period of a couple hours. > >> > >>Does anyone know if this is anormal failure mode for a 5-7 mw tube? > >> > >>Current and voltage tot the tube are still the same as when running. > >> > >>Any help would be appreciated. > >> > >>Thanks in advance > >> > >> > >>73's > >>PaulC KB1RP > >> > >> > > > >Hi Paul, > > > >Yes, I had this happen to one also. > > > >I was told that the helium actually slowly diffuses out through the glass > >and eventually reaches a low enough level that you're left with a big > >neon bulb :-( > > > >Zack W9SZ > > > >-- > > > > > > I'm not so sure that this is the problem. If it was lack of helium, wouldn't > there still be some sort of reduced beam output because of the helium neon > plasma? Since the tube is still starting and appears to be operating, I > would suspect one of the mirrors has been bumped or has shaken loose. > > If the problem is caused by helium depletion, the tube can be restored > easily and cheaply. > > Fortunately, neon is a bigger molecule and does not escape from the tube. > > Helium is a small molecule and it's escape is inevitable. > > Since the tube is operated at a pressure lower than atmospheric pressure, > oxygen and nitrogen tend to leak INTO the tube-but not much-because those > molecules are large too. > > So, putting a very small ammount of helium into the tube is EASY. > > Pressurize the tube at 1 psia in a helium atmosphere for an hour or so, then > RETEST. Repeat until the tube lights. > > DO NOT overfill the tube, it will not work if there is too much helium. > > If you have a relative power meter, you can repeat the filling procedure > till the output power peaks. > > A commonly accepted method of replenishing the helium supply is to put the > tube in a balloon, then get it filled with helium. Thats all it takes- > > You can use industrial grade helium-hi purity gas isn't necessary because > the contaminates mixed with helium are too large to force their way INTO the > tube. > > The above info assumes that the mirrors aren't damaged. > > Enjoy...Art, KY1K. > > >From owner-laser Tue Mar 25 17:42:28 1997 Return-Path: Received: by berlioz.nsc.com (4.1/SMI-4.1) id AA00960; Tue, 25 Mar 97 17:42:28 PST Content-Length: 1267 Message-Id: X-Mailer: XFMail 1.0 [p0] on Linux Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 8bit Mime-Version: 1.0 Date: Tue, 25 Mar 1997 20:00:43 -0500 (EST) From: wayne hilliard To: Laser Messages Sender: owner-laser@berlioz.nsc.com Precedence: bulk Hi guys heres my laser status as of 03-25-97. TX side: 2 mw (+-1 mw) laser pen modulated at 500 hz mounted on a home brew az-el mount that uses 1 inch micrometers as adjustment screws. RX side: I am experimenting with: radio shack phototransister. panasonic pin photo-diode digikey part # PN334PA-ND. burr-brown optical sensor digikey part # OPT202P-ND. Optical components: 4.5 inch meade reflector 2 inch salvaged retractor department store type. I have tested across a 200 foot path 400 foot round trip with : 4.5 inch and phototransister 2 inch and a photo-diode with opamp. I have gotten successful signal return off of a truck reflector mounted on a tree from both of the above setups. This was done though 2 layers of house glass (Its too cold in Vermont this time of year to spend much time outside). I will be trying the 4.5 and photo-diode later this week. I will try the burr-brown device later on after I get a feel for the optics involved. 73 for now Wayne Hilliard "If computers are making the world a global village, KA1CXD and I can't figure out how to use one, does that woody@sover.net make me the global village idiot ?" Shoe >From owner-laser Wed Mar 26 02:19:32 1997 Return-Path: Received: by berlioz.nsc.com (4.1/SMI-4.1) id AA17733; Wed, 26 Mar 97 02:19:32 PST Date: Wed, 26 Mar 97 10:16:19 UT From: "John Yurek" Message-Id: To: "Laser Reflector" Subject: Weak Signal Laser work... Sender: owner-laser@berlioz.nsc.com Precedence: bulk Weak Signal Laser Work ------------------------------------ Sorry I haven't been around much this past week. I've been busy trying to prove a concept that's been wondering around in my head now for the past couple of months. I'm dumping the wide band output of my optical front end into an A/D converter on an IBM clone computer. On the computer I'm running an FFT program with LONG integration times. Setting the computer for an integration time of 1 minute I can begin to see a signal working it's way up out of the noise after approx. 30 seconds. After 1 minute of integration I have +2 dB signal to noise ratio. The laser signal that I'm working with is -60 dB below the noise floor in a 200 Hz passband. (700 to 900 Hz) Yes that's NOT a typo (minus sixty dB ) !!! At these signal levels I can't being to hear anything when listening to the output of the front end in the 200 Hz filter and I have over 30 years weak signal EME and VHF/UHF CW tropo experience. At first I didn't believe it but after several days of trying to disprove this I can't find anything wrong with the system. It's just flat out working better than anything I've ever tried in the past along these lines. Of course 1 minute of integration time will make for a very slow QSO but at least I know this can be done and should make for some very interesting experiments this summer on paths that I previously thought were impossible! Of course with stronger signals the integration time can be made much shorter. I have no idea at this time what longer integration times will do but there is probably a law of diminishing returns going on here somewhere. The laser is being directly modulated 100% with an 800 Hz 50% duty cycle square wave derived from a crystal controlled divider chain. Extreme stability is needed on the audio tone to be compatible with my software and the extremely long integration times. I made some digital audio recordings of the -60 dB laser signals and dumped them to .WAV files for later analysis. Listening to these with various types of narrow band filters I still can't hear anything at all. However, running the FFT program on these files also confirms the presence of a signal after approx. 30 to 45 seconds of integration time. After running 60 seconds the signal is again +1.9 dB out of the noise. I'll provide more details on this as the experiments progress. As it is right now I've been spending way too much time writing Email instead of using the computer to compile source code and smoking up the basement with the soldering iron! John K3PGP@msn.com >From owner-laser Wed Mar 26 18:11:18 1997 Return-Path: Received: by berlioz.nsc.com (4.1/SMI-4.1) id AA18417; Wed, 26 Mar 97 18:11:18 PST Date: Wed, 26 Mar 1997 20:51:03 -0500 (EST) Message-Id: <2.2.16.19970326211250.27cf7fd4@mail.snet.net> X-Sender: paulc@mail.snet.net X-Mailer: Windows Eudora Pro Version 2.2 (16) Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" To: laser@berlioz.nsc.com From: "Paul A. Cianciolo" Subject: 940 nm beacon on the air!! Sender: owner-laser@berlioz.nsc.com Precedence: bulk Hello All, I got My 512 IR diode array up( only 65') on the tower tonight. I have a CW keyer running a beacon message. Best DX so far was 500' With a BB OPT 202 no lens.. Plenty of signal... almost blocking the RX... Got a couple of LOS shots I am looking at. Also 1 with WZ1V. Just thought I say something 73's PaulC KB1RP >From owner-laser Thu Mar 27 08:23:35 1997 Return-Path: Received: by berlioz.nsc.com (4.1/SMI-4.1) id AA14182; Thu, 27 Mar 97 08:23:35 PST Message-Id: <199703271619.LAA06059@host-04.colby.edu> X-Sender: aballen@colby.edu X-Mailer: Windows Eudora Light Version 1.5.2 Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Date: Thu, 27 Mar 1997 11:19:31 -0500 To: laser@berlioz.nsc.com From: "Art Allen, KY1K" Subject: non-los laser qso? Sender: owner-laser@berlioz.nsc.com Precedence: bulk Hi Everyone, I've read John's message regarding his recovery of a very weak laser signal by using electronic ultra long integration time periods. I think it was one of the MOST important messages EVER POSTED ON THE REFLECTOR. While there is no magic in this technology, it is a practical implementation of a concept that was (until recently) just 'theory'. I'm wondering just exactly what is the short fall in laser EME returns?? Does this technology make laser EME possible for us beginner types? Also, regarding non-los paths... Technically, light is line of sight (like vhf hi hi). But, light does bend from the earths gravity (since photons have finite mass). Additionally, light ducts through channells in the atmosphere and varying atmospherics makes light bend (steering). Assuming we avoid the oxygen and nitrogen absorption lines, then laser light is not absorbed in the atmosphere. It is only reflected and scattered. Along these lines, I'm wondering if this makes non-line of sight QSO's possible for amateurs (using electronic ultra long integration time periods). Is it possible that we (as amateurs) could use these techniques to discover pulsars in space? That would be neat (but not laser related, sorry). Since comm'l tower strobes are pulsed, and each is different, then this technology should allow us to identify tower lights on the horizon that our eyes can't see/that can't be detected with conventional means. That would be great for calibrating alt/az readouts for laser aiming purposes. Maybe these techniques might allow us to complete long non-los all water path QSO's, put the laser 1 cm off the water level, and have someone listen 50 or 100 miles away?? Hey, AA1A, u wanna try a P-town to Mid-Coastal Maine QSO, it would be a world record!!!! Maybe we could complete a transatlantic QSO on laser, and we could claim the Brennan trophy hi hi (yes, I'm nuts, we ALL knew that already!). Geostationary satellites might provide adequate reflections, since they DON'T MOVE-a world record AND transatlantic QSO might be possible! Work an uncollimated led at 5 or 10 miles away? If it takes a week to complete the QSO, then so be it!! It sounds like this technology opens ALOT of new doors for us! I certainly hope John gets out of the lab long enough to continue reporting his ongoing research. GL..Art, KY1K. PS-regarding LARGE LIGHT COLLECTORS- If anyone wants a BIG light collector, they are available (54 inch by 40 inch fresnel, $49.95 from Electronic Goldmine Inc). If that isn't big enough, get some mirrored glass and cut it into 1 inch squares. Line the surface of your 12 foot dish tvro/eme array with them, and place a PM tube at the feed! Maybe some sort of very reflective metal foil could be used, that wouldnt even mess up the functionality of the dish for rf! WE HOWDY, look out! Most dishes already have manual alt/az controls and most already point at geostationary satellites!! >From owner-laser Thu Mar 27 12:51:55 1997 Return-Path: Received: by berlioz.nsc.com (4.1/SMI-4.1) id AA23862; Thu, 27 Mar 97 12:51:55 PST Date: Thu, 27 Mar 97 12:51:50 PST From: jmoss (Jim Moss) Message-Id: <9703272051.AA23855@berlioz.nsc.com> To: laser Subject: lense/mirror measurements Sender: owner-laser@berlioz.nsc.com Precedence: bulk Hi... I'm back... Had a great time riding a ship in the Carribean for a week and a half. You all were really busy sending lots of email! The light pen I used was a pen light (not a laser) so it exposed a large conical area of white light. The readings were all relative to a 1/4" square detector. So the gains are in dB relative to that. One of the conclusions that you an draw from the data, is that the fresnel lenses are pretty good. I also note that they do not focus to a point as well, and thus need a larger detector. The other advantage of the fresnel lense that I used, was that it is a book page magnifier and is rigid, no floppy thin plastic to mess with. (But there is a frequency effect, that I haven't looked at yet.) Jim WB9AJZ/6 >From owner-laser Thu Mar 27 18:17:42 1997 Return-Path: Received: by berlioz.nsc.com (4.1/SMI-4.1) id AA05427; Thu, 27 Mar 97 18:17:42 PST Message-Id: <01BC3AD9.653026E0@kevinh.ionimplant.com> From: Kevin Hague To: "'laser@berlioz.nsc.com'" Subject: Laser comm during "Super Inversion" Date: Thu, 27 Mar 1997 18:04:57 -0800 Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: quoted-printable Sender: owner-laser@berlioz.nsc.com Precedence: bulk I wonder what the possibilities of using an atmospheric "Super = Inversions" to do laser comm. I once read a write-up on some = inversions in San Diego where people on the beach could see Islands = hundreds of miles away in Mexico! The strange thing was the islands = were upside down on the horizon.(like a mirror reflection) I have seen = something similar in the central valley of California. -Kevin N5XSA >From owner-laser Fri Mar 28 01:39:24 1997 Return-Path: Received: by berlioz.nsc.com (4.1/SMI-4.1) id AA13643; Fri, 28 Mar 97 01:39:24 PST Date: Fri, 28 Mar 97 09:33:37 UT From: "John Yurek" Message-Id: To: "Laser Reflector" Subject: -43 dB Laser Signal Detection with FFT ! 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MF36!%I$`?Q0>$@N_Y3]NLEFH5!<:3DD63`9=^%]02P$",@L4``(`"`"=(WPB M6[,U\H4T``!].```"0```````````"``MH$`````+30S9$(N:G!G4$L%!@`` 0```!``$`-P```*PT```````` ` end >From owner-laser Fri Mar 28 04:21:50 1997 Return-Path: Received: by berlioz.nsc.com (4.1/SMI-4.1) id AA17677; Fri, 28 Mar 97 04:21:50 PST Message-Id: <199703281219.HAA19328@host-04.colby.edu> X-Sender: aballen@colby.edu X-Mailer: Windows Eudora Light Version 1.5.2 Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Date: Fri, 28 Mar 1997 07:19:34 -0500 To: laser@berlioz.nsc.com From: "Art Allen, KY1K" Subject: non hams on reflector? Sender: owner-laser@berlioz.nsc.com Precedence: bulk Hey Guys, I've run into a young man who is interested in laser communication. He is not a ham. Is he allowed to join the list and participate, or should I just NOT mention the list to him? Personally, I would would work the devil himself, even if he didn't have a license. Since a license isn't required for laser work, should we allow non-hams in the list? I would say he should be allowed to join, wonder what others say? Art... >From owner-laser Fri Mar 28 04:21:41 1997 Return-Path: Received: by berlioz.nsc.com (4.1/SMI-4.1) id AA17667; Fri, 28 Mar 97 04:21:41 PST Message-Id: <199703281219.HAA19335@host-04.colby.edu> X-Sender: aballen@colby.edu X-Mailer: Windows Eudora Light Version 1.5.2 Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Date: Fri, 28 Mar 1997 07:19:38 -0500 To: laser@berlioz.nsc.com From: "Art Allen, KY1K" Subject: Laser comm during "Super Inversion" Sender: owner-laser@berlioz.nsc.com Precedence: bulk -----------quoted text starts----------- > >I wonder what the possibilities of using an atmospheric "Super Inversions" to do laser comm. I once read a write-up on some inversions in San Diego where people on the beach could see Islands hundreds of miles away in Mexico! The strange thing was the islands were upside down on the horizon.(like a mirror reflection) I have seen something similar in the central valley of California. > -----------quoted text ends----------- Optical ducting is very REAL. With wideband light (of mixed colors), the image scatters and becomes a blurry blob over long distances. So, distant images are often seen WITHOUT people realizing what they are. We have seen recent images of orbiting satellites taken from the ground. In white light, they are nothing but blobs. But, if they use a narrowband filter, the images come out amazing clear! I saw a MIR photo done by an amateur on the web, it was amazing. Monochromatic light from a laser is single frequency and has a much better chance of 'staying together in a single beam' when projected over water. I think that optical ducting over water is there-just begging for laser comm guys to step up and aim some beams at it and call cq. I bet the signals would be strong too. KH6CP mentioned some ham talking about optical ducting at a vhf conference, he was claiming to see ships 100+ miles away on the Great Lakes in the early AM hours. Obviously, ships have some fairly high power lights at night, but nothing that would compare to a laser! Signals from a laser should be pounding in HARD compared to ships lighting. If we ever get our laser aiming advanced enough to use stars to aim AZ, then we could lock a laser at zero degrees elevation and run some tests over water. I'm working towards that capability now. Enjoy...Art... >From owner-laser Fri Mar 28 06:34:15 1997 Return-Path: Received: by berlioz.nsc.com (4.1/SMI-4.1) id AA21503; Fri, 28 Mar 97 06:34:15 PST Message-Id: <199703281432.JAA24346@host-04.colby.edu> X-Sender: aballen@colby.edu X-Mailer: Windows Eudora Light Version 1.5.2 Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Date: Fri, 28 Mar 1997 09:32:33 -0500 To: laser@berlioz.nsc.com From: "Art Allen, KY1K" Subject: level reference line? Sender: owner-laser@berlioz.nsc.com Precedence: bulk <<< No Message Collected >>> >From owner-laser Fri Mar 28 11:57:31 1997 Return-Path: Received: by berlioz.nsc.com (4.1/SMI-4.1) id AA02153; Fri, 28 Mar 97 11:57:31 PST From: sjnoll@ix.netcom.com Date: Fri, 28 Mar 1997 13:48:20 -0600 (CST) Message-Id: <199703281948.NAA23697@dfw-ix14.ix.netcom.com> Mime-Version: 1.0 Content-Type: text/plain Content-Transfer-Encoding: 7bit Subject: Re: non hams on reflector? To: laser@berlioz.nsc.com In-Reply-To: <199703281219.HAA19328@host-04.colby.edu> X-Mailer: SPRY Mail Version: 04.10.06.22 Sender: owner-laser@berlioz.nsc.com Precedence: bulk For my money... everyone should be welcome. And as you say, a license isn't required anyway. Steve J. Noll | Ventura CA | WA6EJO | sjnoll@ix.netcom.com | http://www.netcom.com/~sjnoll/usedequip.html | http://www.netcom.com/~sjnoll/peltier.html >From owner-laser Fri Mar 28 13:35:59 1997 Return-Path: Received: by berlioz.nsc.com (4.1/SMI-4.1) id AA05613; Fri, 28 Mar 97 13:35:59 PST Date: Fri, 28 Mar 97 17:20:51 UT From: "John Yurek" Message-Id: To: "Laser Reflector" Subject: Decoding Graphic Images Sender: owner-laser@berlioz.nsc.com Precedence: bulk To all: Several people have sent Email saying that the Laser Reflector will not transfer files, only ASCII text. This is true and that's why the .JPG picture file was sent as a UUENCODED ASCII text file! If you are using Windows 95 (or Windows 3.1) all you need is Winzip 6.2 available at www.winzip.com. I am using the W95 version but I'm told the Windows 3.1 version works the same. Save the message as an ASCII text file with the extension of .UUE. Click on it and Winzip will open it. Unzip the file and you will have -43db.jpg! I KNOW this works because several people including myself have gotten the picture back from the laser reflector and it looks as good as the original! If you are not using Windows 95 or 3.1 then you will have to track down UUDECODE. Try one of the web search engines. I have this file and it works from a MSDOS prompt but I forgot where I got it from! It is also available for the MAC and Unix systems so there should be 100% compatibility here. UUENCODE and UUDECODE were written for the express purpose of transferring binary files as ASCII text files !!! John K3PGP@msn.com >From owner-laser Fri Mar 28 15:24:39 1997 Return-Path: Received: by berlioz.nsc.com (4.1/SMI-4.1) id AA09225; Fri, 28 Mar 97 15:24:39 PST Date: Fri, 28 Mar 97 15:21:47 PST From: jmoss (Jim Moss) Message-Id: <9703282321.AA09109@berlioz.nsc.com> To: K3PGP@msn.com Subject: Re: -43 dB Laser Signal Detection with FFT ! Cc: laser Sender: owner-laser@berlioz.nsc.com Precedence: bulk John, I put your graphic on the web page. Also the SSB/FM/Data email has been placed there as well. Web page is: http://www.qsl.net/wb9ajz/laser/laser.htm If anyone has info they want cataloged there, let me know. I will be updating the mailarchive files there on Monday (each month). And I will also update the membership list of the mailserver there as well. 73, Jim WB9AJZ/6 CM87xi Sunnyvale, CA. >From owner-laser Fri Mar 28 16:09:28 1997 Return-Path: Received: by berlioz.nsc.com (4.1/SMI-4.1) id AA10669; Fri, 28 Mar 97 16:09:28 PST From: Kb8tej1@aol.com Date: Fri, 28 Mar 1997 19:05:18 -0500 (EST) Message-Id: <970328190518_1020457856@emout14.mail.aol.com> To: aballen@colby.edu, laser@berlioz.nsc.com Subject: Re: non hams on reflector? Sender: owner-laser@berlioz.nsc.com Precedence: bulk Why not? BTW do u have a QSL route/manager for the Devil? 73 Rob >From owner-laser Fri Mar 28 16:11:40 1997 Return-Path: Received: by berlioz.nsc.com (4.1/SMI-4.1) id AA10747; Fri, 28 Mar 97 16:11:40 PST From: Kb8tej1@aol.com Date: Fri, 28 Mar 1997 19:10:51 -0500 (EST) Message-Id: <970328191051_-636410874@emout19.mail.aol.com> To: aballen@colby.edu, laser@berlioz.nsc.com Subject: Re: Laser comm during "Super Inversion" Sender: owner-laser@berlioz.nsc.com Precedence: bulk Damn Art, ol sailor like me should have thought about using a star sight as a means of tracking, Damn, Damn, etc. With land navigation you could set your bench mark pretty close by reciprocal bearings fron known land marks then figure the bearing to target and then use Polaris for abt 2deg accuracy or multiple sights from the Emphemeris to get it more exact! Dumb Dumb etc, I missed the first non los post whoand what? 73 Rob >From owner-laser Fri Mar 28 16:13:08 1997 Return-Path: Received: by berlioz.nsc.com (4.1/SMI-4.1) id AA10808; Fri, 28 Mar 97 16:13:08 PST From: Kb8tej1@aol.com Date: Fri, 28 Mar 1997 19:12:09 -0500 (EST) Message-Id: <970328191208_-1202635000@emout03.mail.aol.com> To: aballen@colby.edu, laser@berlioz.nsc.com Subject: Re: level reference line? Sender: owner-laser@berlioz.nsc.com Precedence: bulk headers no post rpt pse tnx Rob >From owner-laser Fri Mar 28 17:08:24 1997 Return-Path: Received: by berlioz.nsc.com (4.1/SMI-4.1) id AA12533; Fri, 28 Mar 97 17:08:24 PST Content-Length: 852 Message-Id: X-Mailer: XFMail 1.0 [p0] on Linux Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 8bit Mime-Version: 1.0 In-Reply-To: <199703281219.HAA19328@host-04.colby.edu> Date: Fri, 28 Mar 1997 19:46:31 -0500 (EST) From: wayne hilliard To: Laser Messages Subject: RE: non hams on reflector? Sender: owner-laser@berlioz.nsc.com Precedence: bulk On 28-Mar-97 Art Allen, KY1K wrote: >Hey Guys, > >I've run into a young man who is interested in laser communication. He is >not a ham. > >Is he allowed to join the list and participate, or should I just NOT mention >the list to him? > >Personally, I would would work the devil himself, even if he didn't have a >license. > >Since a license isn't required for laser work, should we allow non-hams in >the list? > >I would say he should be allowed to join, wonder what others say? > >Art... > > > I got no problem with this in fact the more the merrier!! Wayne Hilliard "If computers are making the world a global village, KA1CXD and I can't figure out how to use one, does that woody@sover.net make me the global village idiot ?" Shoe >From owner-laser Fri Mar 28 22:53:33 1997 Return-Path: Received: by berlioz.nsc.com (4.1/SMI-4.1) id AA23324; Fri, 28 Mar 97 22:53:33 PST To: laser@berlioz.nsc.com Date: Sat, 29 Mar 1997 01:51:23 -0500 Message-Id: <19970329.015124.3654.1.K3PGP@juno.com> X-Mailer: Juno 1.23 X-Juno-Line-Breaks: 0-2,4-6,8-10,12-14,16-28,30-47 From: k3pgp@juno.com (John J. Yurek) Sender: owner-laser@berlioz.nsc.com Precedence: bulk On 28-Mar-97 Art Allen, KY1K wrote: >Hey Guys, > >I've run into a young man who is interested in laser communication. He is >not a ham. > >Is he allowed to join the list and participate, or should I just NOT mention >the list to him? > >Personally, I would would work the devil himself, even if he didn't have a >license. > >Since a license isn't required for laser work, should we allow non-hams in >the list? > >I would say he should be allowed to join, wonder what others say? > >Art... > > A-B-S-O-L-U-T-E-L-Y ! ! ! Most of the people I am working with in this area are NOT hams ! However, I think Jim needs to change the welcom greeting when you sign up with the Laser Reflector. Here's what I got when I joined: >This is the LASER mailserver. >It is intended for use by Amateur Radio Operators interested >in laser 2way communications thru air. Maybe it should say something like: >This is the LASER mailserver. >It is intended for use by INDIVIDUALS interested > in laser 2way communications thru air. John K3PGP@juno.com -==- >From owner-laser Fri Mar 28 22:53:26 1997 Return-Path: Received: by berlioz.nsc.com (4.1/SMI-4.1) id AA23318; Fri, 28 Mar 97 22:53:26 PST To: laser@berlioz.nsc.com Date: Sat, 29 Mar 1997 01:45:18 -0500 Subject: Web Page Message-Id: <19970329.015124.3654.0.K3PGP@juno.com> X-Mailer: Juno 1.23 X-Juno-Line-Breaks: 0-11,17-18,23-24,27-28,30-38 From: k3pgp@juno.com (John J. Yurek) Sender: owner-laser@berlioz.nsc.com Precedence: bulk Jim: >John, >I put your graphic on the web page. > >Also the SSB/FM/Data email has been placed there as well. > >Web page is: >http://www.qsl.net/wb9ajz/laser/laser.htm OK - Thanks. The graphic image was compressed down to 320x240 to save transmission time since I wasn't sure if it would make it through the reflector OK or not and I didn't want to waste everyone's time if it didn't. Since several people have asked for the full size 640 x 480 image I will post it. It's only a little bigger and looks a LOT better. You might want to replace the old .JPG file with the new one. There also was a construction article on modifying the Damark Laser Pen. You might want to consider putting that on the web page as well. It seems a LOT of people are now experimenting with these. It appears that the power can be run up on these quite a bit without any problems. I have a bit more info on that as well if anyone needs it. I'll be happy to send updated files to you if you want these. There were a few minor errors in the AM/FM/SSB & laser pen stuff that should be corrected. I'll drop by the web site to see which ones you used and if anything needs updated. Thanks again. John K3PGP@juno.com NOTE: ^ New Email ADR !!! Old account still active temporarily! >From owner-laser Fri Mar 28 23:49:21 1997 Return-Path: Received: by berlioz.nsc.com (4.1/SMI-4.1) id AA24862; Fri, 28 Mar 97 23:49:21 PST To: laser@berlioz.nsc.com Date: Sat, 29 Mar 1997 02:47:41 -0500 Subject: -43dB640.jpg File Description Message-Id: <19970329.024742.3654.3.K3PGP@juno.com> X-Mailer: Juno 1.23 X-Juno-Line-Breaks: 0-2,6-7,10-11,19-20,26-27,33-34,39-40,45-46,52-53,59-64 From: k3pgp@juno.com (John J. Yurek) Sender: owner-laser@berlioz.nsc.com Precedence: bulk File description -43db640.jpg ---------------------------------------- The vertical axis is a LINEAR scale that can be read as a simple voltmeter meaning that a signal that is 50% out of the noise is at +6 dB. The linear scale makes it easier to see weak signals that may be only a couple of dB out of the noise after integration. The actual laser signal in this photo is 43 dB below the noise floor. Since it is difficult to establish a reference (when the signal to noise ratio is zero dB) the following was done: The noise output (No signal) was measured with an HP audio test set with an audio bandpass running from 500 to 1000 Hz with the lens capped on the optical front end. The audio bandpass filtering was done to prevent high frequency noise (above the audible hearing range) from influencing the signal to noise measurements. This allows the dB readings on the audio test set to more closely represent what the human ear hears. If the audio filter were NOT used the noise floor would be higher making the laser signal appear considerably more than 43 dB below the noise floor! A 630 nm signal modulated 100% with an 800 Hz 50% duty cycle square wave (derived from a 8 MHz quartz crystal oscillator and digital divider chain) was then fed into the optical detector and adjusted for +10 dB signal to noise ratio. The signal was then optically attenuated with calibrated LIGHT attenuators until it was 43 dB below the noise floor. (A total of 53 dB attenuation.) Please note that there is NO absolute power calibration (reference to 1 mw) here and 3 dB in this case means half laser power. The only objective of the optical attenuation was to get the signal below the noise floor and NOT to determine absolute signal level. (That will come later!) If the 3 dB optical attenuator were placed in front of a 1 mw laser you would have 0.5 mw coming through the attenuator. I took the picture at -43 dB because the present software has some kind of a problem with I push it below -45 dB. With other software I was able to achieve a +1.9 dB SNR at -60 dB below the noise floor after 60 seconds integration. However the little +1.9 dB spike (although easily seen) wasn't as impressive so I sent the one captured at -43 dB! I am told by VE2IQ that signals like this can be solid copy using PSK and BPSK modulation, especially in the presence of white noise and no QRM, much as we have with laser QSOs. (So far :-^) I will be working on this in the next couple of weeks after some needed parts get here and new software is developed. Basically all that is needed to transmit these modes is an XOR gate inserted in series with the 50% duty cycle square wave signal so the phase can be inverted to represent digital data. Although it's simple to generate these signals, recovering the signal can be quite a challenge, especially when it's below the noise floor! I'll post the results here as soon as I have something working. I don't want to waste everyone's time with graphic images since these can be quite large. However, if there is sufficient interest I will take pictures of the system from time to time and post them here. I will make every effort to compress these images to as small a size as possible. I try to set 40 to 50 K bytes as an upper limit. Unfortunately the UUENCODE program adds quite a bit of overhead to the filesize. John K3PGP@juno.com -==- >From owner-laser Sat Mar 29 10:54:39 1997 Return-Path: Received: by berlioz.nsc.com (4.1/SMI-4.1) id AA11504; Sat, 29 Mar 97 10:54:39 PST Message-Id: <333D6317.3FF9@ssih.com> Date: Sat, 29 Mar 1997 13:44:39 -0500 From: Dave Riley Reply-To: daveaa1a@ssih.com Organization: Broadcast Technical X-Mailer: Mozilla 3.0Gold (Win16; U) Mime-Version: 1.0 To: laser@berlioz.nsc.com Cc: bill@ietc.ca, microwave@wa1mba.org Subject: Laser Transverter Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Sender: owner-laser@berlioz.nsc.com Precedence: bulk Gudday Light Bugs.. Well after the flurry of activity caused by K3PGP et al, I finally finished up a long thought out project.. A Laser Transverter that handles Wideband, SSB, CW, Data, ???.. After taking a clue from the 10ghz transverter, I decided what with limited parts on hand and a like for the least common denominator approach. It came out as follows... 10 Ghz. transverter Laser Transverter =================== ================== Antenna 1' dish 4" lense receive Colimated 5mw diode transmit Receiver/ Ku Band LNA (reworked) Pin Photo Diode Mixer sma 10ghz mixer j-fet preamp,Vlf converter I.F. Gasfet preamp into IC-706 into IC-706 receiver any mode.. Transmitter/ IC-706 @ 146 mhz IC-706 @ 4.040mhz Mixer same sma and gasfet preamp Attenuator, sampler, DBMixer L.O. is same brick L.O. is same as one above.. Output 1/4 watt amp., 1' dish NPN series modulator into 5mw 650nm laser diode.. The thing that makes this fly easier is a RF sensed remote mast mounted type preamplifier.. I send +12 volts up the rg-58 in each case to power the RF switch, Rx/Tx.. It makes a remote setup easier and it's nice to be in the car having a qso just like it was 75 meter AM.. Have also used a set-up like this on the LOWFER band 160-190 khz.. Guess you could say the IC-706 is good for D.C. through light.. This was fun and now am ready for some springtime hilltop qso's.. FN42/41/51 anyone?? Am off to another project but will be listening.. This mode is a GREAT no-code license free ham band eh?? I see many members on this list never make any comments..??.. We could use some discussion in this fertile area.. No question is stupid and answers are always welcome.. Keep the Light on..73..de Dave Riley - AA1A - Marshfield, Mass...... sk >From owner-laser Sat Mar 29 13:51:47 1997 Return-Path: Received: by berlioz.nsc.com (4.1/SMI-4.1) id AA16445; Sat, 29 Mar 97 13:51:47 PST From: Lbo@kktv.com Message-Id: <199703292145.NAA10153@natsemi-bh.nsc.com> To: laser@berlioz.nsc.com Date: 29 Mar 1997 14:52:58 -0700 Subject: Need HeNe Tube Sender: owner-laser@berlioz.nsc.com Precedence: bulk i need a HeNe tube (14" long X 1.5" dia) 5-20mW. Any body have one? de w0rw Paul Signorelli, Las Brisas Observatory, (View LBO's Web Page at http://rainbow.rmi.net/~mugele/lbo) LBO@KKTV.COM, P.O. BOX 6069, Colorado Springs, CO 80934 >From owner-laser Sat Mar 29 15:59:41 1997 Return-Path: Received: by berlioz.nsc.com (4.1/SMI-4.1) id AA19650; Sat, 29 Mar 97 15:59:41 PST Message-Id: <199703292355.SAA05405@outpost.ietc.ca> X-Sender: bill@ietc.ca X-Mailer: Windows Eudora Light Version 1.5.2 Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Date: Sat, 29 Mar 1997 18:56:15 -0500 To: daveaa1a@ssih.com, laser@berlioz.nsc.com From: Bill de Carle Subject: Re: Laser Transverter Sender: owner-laser@berlioz.nsc.com Precedence: bulk At 01:44 PM 3/29/97 -0500, Dave Riley wrote: >Gudday Light Bugs.. > >Well after the flurry of activity caused by K3PGP et al, I finally >finished >up a long thought out project.. A Laser Transverter that handles >Wideband, >SSB, CW, Data, ???.. [snip info on laser transverter] Thanks for the info Dave. Think I forgot to answer your earlier question about distance to town of St. Sauveur .. I would estimate the distance is between 5 and 6 miles as the crow flies. It should be easy because the path is more or less North-South, so the rising / setting sun on the horizon is never in the "eyes" of either end. The link would span a valley where the little town of Morin Heights is located. No high buildings there though. There is a very visible tower on the ridge at the St-Sauveur end, but it is owned by Bell Cellular, and I don't think they'd be willing to let me install a light beam system on that tower for the purpose of saving money on phone calls :) - so I'd have to find someone who lives in that area and who has a clear shot to my site across the valley. There is always a problem of trees here - I have a solar-powered part 15 beacon up on the hill, but for a light link I'd have to cut some trees down for a clear path, or else put up a tower or a mast, which isn't easy because it's a difficult hike to that point from my house, and there is no road, etc. Maybe we can work on 10 Ghz some day. A couple years back during a contest sponsored by ARRL, I went to visit a fellow ham who is into that sort of thing. Forget his call now, but he lives in Ontario, south of Ottawa. I remember driving around with one of his 10 Ghz portable stations, and I was able to work him from several neighboring grids. With his base station, he was able to contact New England states easily on all the VHF/UHF bands including 10 Ghz. I don't have any equipment currently for gigahertz work. But if I hike up to the top of just about any of the mountains round here I can work all sorts of 2 meter repeaters in New England using just a hand-held running a watt or so. Some spots are better than others - there is one nearby called "blue hills" - I've been up there with a portable packet station, and worked everywhere with milliwatts. I have QSO'd with Massachusetts on 2 meters using just the handheld, but I went through one of the repeaters down there. From my house (which is not a good site because there is a ridge directly south of me which is higher than the house, hi!) I can get into the Plattsburgh packet and voice repeaters any time I wish. Although I don't remember the callsigns, I'm sure to be able to hit any repeater in Vermont that has a high antenna. I have a "boomer" antenna for 2 meters but I seldom use that band. There is a repeater on Jay Peak Vt. which comes in like a local machine here. Sorry we didn't make it on 10.141 this afternoon. I didn't hear anything but had the impression you were in there because the number of right curly brackets on my screen was way higher than it should have been statistically. There were even strings of }}} etc. So now I know it was you, Dave. I think the bands were in poor shape today, this morning on 80 meters the usual net I monitor was a disaster - many stations couldn't hear others with whom they are normally armchair copy. Hopefully this will improve before our session at 0400z on 3591 tonite. 73 de Bill VE2IQ >From owner-laser Sun Mar 30 08:23:10 1997 Return-Path: Received: by berlioz.nsc.com (4.1/SMI-4.1) id AA10631; Sun, 30 Mar 97 08:23:10 PST Message-Id: <199703301621.LAA12740@host-04.colby.edu> X-Sender: aballen@colby.edu X-Mailer: Windows Eudora Light Version 1.5.2 Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Date: Sun, 30 Mar 1997 11:21:48 -0500 To: laser@berlioz.nsc.com From: "Art Allen, KY1K" Subject: airplane scatter? Sender: owner-laser@berlioz.nsc.com Precedence: bulk Hi Everyone, I'm wondering about airplane scatter for laser communications. If we bounce lasers off of airplanes, it removes a very major obstacle we face for long distance DX record Q's-which is finding distant land peaks with optical line of sight paths between them. Further, we wouldn't have to travel for hours, just to get to a world class mountain top, or deal with the owners of such peaks for 'permission' to use them. I've gathered some basic info and would like to report it to the group. ---------------- LOS from airplane's prospective -------------------- If we look at large comm'l airliners as reflectors, we find they fly at 15,000 to 40,000 feet depending on the length of the flight. This gives them 100 to 300+ mile line of sight (from the cockpit), which makes up to 600 mile laser Q's worth investigating. ---------------- where do they fly? -------------------- I've also discovered that for longer distance flights they use 'flyways', which are agreed to and established by the industry. Even short commuter hops use flyways, in order to avoid airspace violations of other airports and military installations. So, as a general rule, they fly in fairly organized super highways in the sky. Private planes do not follow these conventions. ---------- Possible means of tracking them --------------- Obviously, locating a plane to reflect the laser is a problem. If 2 stations were located along a major flight path, a random QSO could be made. To complete the QSO quickly, it would be ideal to actually track the plane. They might transmit GPS info or similar info automatically-these days, that info could be piggy backed on a standard transponder signal- Meteor Scatter protocol could be used if tracking of a particular plane is not possible. Access to a radar setup would be ideal, but not practical. Some weather radar resources available on the WWW might make this info available in real time, not sure. Practically, I think the best thing we can do is to use our receivers to search the sky for strobe lights!*** Planes have big strobe lights and they are modulated and each is a little different than the others-so, we can probably discriminate between multiple planes in the same area of the sky. AA1A has reported that he can hear strobes from aircraft with a 4 inch lens and a solid state detector. In fact, he reported that he can 'hear' them well past the range he looses visual sight of them. So, tracking planes by listening for their strobes is probably practical. ***It appears that a modest TX/RX can actually serve to track a plane by listening for the reflection off the plane itself (align tx and rx and operate in full duplex mode). See example below. ---------------- Signal Strength of reflection -------------------- Let's assume the plane is 100 km distant and located midway between the stations that want to work. So, we are investigating the feasibility of a 200 km laser qso. Assume some sloppy laser specs (2 milliradian divergence at 1 milliwatt laser tx power). Lets also assume 1 square meter of reflection surface from the plane-most planes would have much larger effective areas. Let's assume that we don't loose any signal in the atmosphere (for the purposes of this example). A 2 millirad laser will illuminate a 200 meter circle at a distance of 100 km. The area of a 200 m circle is 31,400 square meters. So, our plane could reflect 1/31,400 of our beam back to earth. This means the plane would appear as a 31.8 nanowatt transmitter when viewed from the receiving (far end) site of the QSO path. So, the question here is 'can we hear 31.8 nanowatts at a range of 100 km with a reasonably sized receiving lens?' PM Tubes can receive 10 e-15 watts and solid state detectors can receive 10 e-12 watts (at 1 hz bandwidth). Let's assume 100 millirad divergence, a 31.8 nanowatt (effective) tx and a .01 square meter rx lens (10 cm square lens)... Let's also assume that we don't loose any signal in the atmosphere... Using WA6EJO's basic range formula, we can detect the planes reflection @ 31.8 km if the solid state detector is used. With the PMT, we can detect the planes reflection @ 3,180 km! Can this possibly be correct? I've checked my figures, I invite you to do the same. ---------------- Conclusion -------------------- It appears feasible that milliwatt class lasers and modest sized light gathering lenses with solid state RX's can provide enough reflected power from the plane so that the EACH station is a SELF CONTAINED tracking unit. Laser comm in the 200 km range is possible, probably slightly marginal. Using a PM tube RX, it appears that QSO's in this range class are VERY EASY and that the reflection off the plane as received from the transmitting station should be LOUD-tracking should be EASY. ---------------- laser safety issues -------------------- There is no problem with CDRH compliance with the plane at 10 km away (or more) -the power density of the beam is low at that range. BUT, if the plane was flying TOWARDS the transmitter, the pilots would see it and it would be VERY BRIGHT to their naked eyes. It's a serious offense to shine ANY light at ANY aircraft, if it threatens safety. TRACKING an aircraft and HOLDING A LASER BEAM on a plane might be considered as threatening the planes safety! The pilots might be distracted, or unable to see ground based landmarks because of the laser light. I believe that use of an IR laser tx would be legal because it could not distract the pilot or threaten saftey. USE extreme caution if you shine a visible laser at an aircraft! If you can't confirm the planes direction of flight, then DON'T TURN ON THE LASER!! It might be best NOT TO DO IT AT ALL (unless you are sure of the planes direction of flight)! ---------------- THE END -------------------- Returning you to your regularly scheduled channel. GL...Art, KY1K. >From owner-laser Sun Mar 30 13:04:53 1997 Return-Path: Received: by berlioz.nsc.com (4.1/SMI-4.1) id AA16980; Sun, 30 Mar 97 13:04:53 PST To: laser@berlioz.nsc.com Date: Sun, 30 Mar 1997 16:02:52 -0500 Subject: re: Airplane Scatter Message-Id: <19970330.160252.11934.0.K3PGP@juno.com> X-Mailer: Juno 1.23 X-Juno-Line-Breaks: 0-2,4-23,26-27,29-30,32-33,37-38,45-46,50-51,58-63, 68-69,75-76,83-94 From: k3pgp@juno.com (John J. Yurek) Sender: owner-laser@berlioz.nsc.com Precedence: bulk Using Airplanes as reflectors: ------------------------------------------ This is from a very old Email sent to me from W3GFS concerning my use of a high power (800 to 1000 watt) ruby rod system for EME: >Concerning safety - you must pay attention to this issue, particularly >if you operate in the visible (wavelength which can pass thru glass >cockpits!!). Laser light shows in Los Vegas have gotten into trouble >by unintentionally illuminating commercial airline cockpits. >Fortunately, no accidents yet. Peak power is the concern for you, not >average. Your peak power will be very high and the problem becomes >more serious. Additionally, the Laser Clearing House at US SPACE >COMMAND (Cheyenne mountain in Colorado Springs) will determine from >your laser specs whether or not your system presents a hazard to any >satellites (some of them have very sensitive earth-looking sensors). > >Good luck & have fun. > >73, > >John Albertine >W3GFS Although I never bothered to look it up, it is my understanding that it is against FAA regulations to point ANY kind of laser (IR or otherwise) at an aircraft and as such is a Federal offense! I think someone sent the actual FAA rules to me in an Email but so far I haven't located it. With that out of the way and since a year has passed I think it's probably safe to say that I did exactly that. I tried looking for reflections from aircraft last summer using my IR setup as a laser radar. I was using a 5 mw IR unit out of an old laser printer for transmit and an unknown solid state detector (with optical biasing) with a 4 inch lens for receive. I had no problem detecting reflections off of aircraft that were fairly close. I made a point to only try this on planes that passed overhead and were going away from me. However, I made no attempt to try to hit one on the horizon since there was no way I could be sure of it's direction of travel. If it were coming toward me even an IR laser can appear quite bright since it isn't totally invisible when in a dark environment. NOTE: This depends on just what wavelength your IR laser runs at. Mine are just at the bottom end of the visible spectrum - 780 nm. If you can find one operating further into the IR region so it is TOTALLY invisible then no one would even know about it! I don't suggest anyone try this until your sure it's legal. (Fat chance!) As far as I'm concerned there is a great potential for disaster. If you do this on a regular basis from the same location there won't be much trouble locating you and they WILL come looking for you! But at least you and I know it can be done. :-^) I have no idea though as to range. Like I said I didn't feel safe pointing at an aircraft on the horizon even with an IR unit! ----- A few words on using any object as a passive reflector: Since two stations would be using the same passive target there is a potential for QRM. That is your own signal scattering back and QRMing the other station, assuming you are running full duplex. I have had this happen many times when trying to use local objects such as water towers and communications towers as reflectors. The secret is to use the subcarrier system with both stations on different subcarrier frequencies! In past tests I ended up transmitting using a 15 Khz subcarrier with the other station using 25 Khz and it worked like a champ. Tuning to 15 Khz I could hear my own reflections coming back (use this to line up on the target!) and tuning to 25 Khz I could hear the other station. Of course we were running full duplex! NOTE: It's also possible to put an 800 hz tone on the laser transmitter at the same time and use this for tracking. (That way you only need an audio amplifier and won't have to re-tune.) However, if you are going to use multiply carriers you MUST bias the laser diode modulator for linear operation and make sure the 800 Hz tone (as well as the subcarrier) are sine waves. The harmonics of an 800 Hz square wave with just about wipe out any other subcarriers on the laser! NOTE for all newcomers: (And PILOTS!) "DO NOT LOOK INTO LASER WITH REMAINING EYE!" I guess this was from an old timer that tried it ...... ONCE! John K3PGP@juno.com -==- >From owner-laser Sun Mar 30 17:10:09 1997 Return-Path: Received: by berlioz.nsc.com (4.1/SMI-4.1) id AA23725; Sun, 30 Mar 97 17:10:09 PST To: laser@berlioz.nsc.com Date: Sun, 30 Mar 1997 20:07:25 -0500 Subject: A Brief History of laser EME Message-Id: <19970330.200840.16078.2.K3PGP@juno.com> X-Mailer: Juno 1.23 X-Juno-Line-Breaks: 0-2,6-11,14-15,17-20,22-23,32-33,43-46,50-55,59-60, 66-73,78-87,90-91,94-105,111-116,124-125,135-137,147-148, 160-161,171-183,189-190,202-203,210-217,220-225 From: k3pgp@juno.com (John J. Yurek) Sender: owner-laser@berlioz.nsc.com Precedence: bulk A Brief History of laser EME ----------------------------------------- I have been cleaning up my hard drive today and as I ran across anything on laser EME I dumped it to a file. The following are notes that I put together over the past year or so on the history of laser EME. I have tried to include dates when available. ----- K3PGP: 09/19/96 I had some extra time today so I went over to the library. I managed to find an article that describes the first laser echoes returned from the lunar SURFACE!!! This is BEFORE the Apollo astronauts visited the moon and setup the retro-reflectors! ----- >From Scientific American 1970 March, page 38 - Titled: The Lunar Laser Reflector. "More recently light from ruby lasers has been directed at the moon and the weak signal reflected back has been detected. The first detection of ruby laser light reflected from the lunar surface was accomplished eight years ago (1962) by a group at the Massachusetts Institute of Technology. Laser pulses of one-millisecond duration were transmitted through a 12 inch telescope. With a 48 inch telescope as the receiver, many shots were required to define a detectable return signal. A similar experiment was carried out in 1964 by Russian astronomers, who used a 104 inch telescope for both transmitting and receiving." "The first experiment with enough accuracy to be of scientific value" (K3PGP: the goal here was DISTANCE measurement!?) "was conducted by the same Russian group in the fall of 1965, when they used the 104 inch telescope to transmit and detect pulses of 50 nanosecond duration produced by a "Q-switched" (short pulse) ruby laser. The experiment established the earth-moon distance to an accuracy of 600 feet. A fundamental limitation on the precision that can be obtained by bouncing a light beam directly off the lunar surface arises from the curvature and the irregularity of the surface, which spread out the arrival time of the returned signal." ----- "During their brief sojourn on the moon Edwin E. Aldrin, Jr. and Neil A. Armstrong set up an array of "retro-reflectors" that can return a laser signal with an intensity between 10 and 100 times greater than that produced by reflection from the natural surface." ----- K3PGP: 09/19/96 As I pointed out earlier, the retro-reflectors are not very useful for amateur EME because the returned beam is only about 20 km in diameter. However, they would serve a useful purpose in initially setting up a laser EME rig because of the stronger returned echo. All of the above experiments are based on knowing the arrival time of the returned echo. For communications purposes (EME - other than echo tests) we will NOT have this luxury and as such will need a better signal to noise ratio. I am hoping that improvements in optical detectors in the past 35 years or so will allow us to be able to detect reflections from the lunar surface with reasonable sized optics. ----- K3PGP: 03/30/96 NOTE: Add to above long term FFT integration techniques! Up until now I've been working on a high power (800 to 1000 watt) pulsed ruby rod transmitter. For the time being I am abandoning that project in favor of a much lower powered (milliwatt range) laser rig and trying to make up the difference with optics and coherent (FFT long integration time) receiving techniques. ----- >From the Email Bag! ----- 08/14/96 First I thought laser EME to be impossible but there might indeed be possibilities because of some scattering anomaly of the lunar surface. Very interesting. A 'negative' note: you can approximate the optical scattering loss by comparing the magnitudes of the Sun (-26.7) and full Moon (-12.5). As m=-2.5log10(F/F0), you get ratio of about 500000 in flux density [Wm-2]. Cheers, Kaj oh6eh ----- 08/11/96 The lit surface is a reduced black body, meaning that it is at a temperature (spectrally) of 5000K from the sun, which is diluted due to distance and albedo. The unlit surface is lit by sunlight which has diffracted around the limb of the Earth. Computing the temperature would be tricky, but the extra noise compared to the lit part would be negligible. Brian kd6tla ----- You idea sounds like a fun area to play in. As you go to shorter wavelengths from UHF & microwaves, the available antenna gain goes up. That's the real advantage of optical/IR wavelengths. A 1 meter dish is about 10**5 or 10**6 wavelengths across. That is a lot of db!!! The downside of the gain is the narrow beam width - you must point correspondingly accurately (remember, the moon moves across the sky - it isn't geostationary) and you must point at the retro which is more difficult than just pointing at the moon. Ranging and comm are different, you need to keep that in mind. Ranging uses very hi peak power, short pulse systems of low average power. PRF might be 1 pulse per second or so. Not great for data transfer! They also have a narrow range gate (you know the approximate range to the moon & when to look) The person you are communicating with does not know when you transmitted and thus has no range gate and requires a pretty high S/N. Keep that in mind as you calculate system power. You will also not have a coherent detection system (like in a superhet), these detection systems are direct from "RF" to video and low quantum efficiency. That will change the equation over RF systems. Visible vs IR is an interesting question. I would encourage you to stay with visible unless you have experience with IR systems (K3PGP: IR in this case refers to a Co2 laser which operates at 10.6 microns or 10,600 nm and NOT the higher frequency range that IR laser diodes operate at - typically 780 to 880 nm. For the purpose of this discusion 780 to 880 nm systems are considered in the visible range.) - it will be much cheaper and easier to work with. Also, sensitive IR detectors are expensive and, for CO2 wavelengths, need to operate around 77K (liquid nitrogen temperatures). Room temperature IR detectors, like bolometers, have no sensitivity or fast response time. NASA placed a retro-reflector on the moon for the very purpose of ranging and did successful experiments with it. I suggest you find published papers reporting those results and the test setup which was employed. I believe they used visible. The gain of a retro-reflector comes from its narrow return angle, it does not reflect over 2*pi sr. Consequently, the receiver at the other end of your comm link must be close enough to be able to see the reflection. You need to check the specs on NASA's retro. Also need to see what kind of a retro it is. What wavelengths does it reflect? Metal corner cubes are fine for visible & IR while glass retros which are silvered on the back only reflect the visible. You'll need to do some homework. I think I saw an exhibit of the retro-reflectors in the Smithsonian Air & Space. Concerning safety - you must pay attention to this issue, particularly if you operate in the visible (wavelength which can pass through glass cockpits!!). Laser light shows in Los Vegas have gotten into trouble by unintentionally illuminating commercial airline cockpits. Fortunately, no accidents yet. Peak power is the concern for you, not average. Your peak power will be very high and the problem becomes more serious. Additionally, the Laser Clearing House at US SPACE COMMAND (Cheyenne mountain in Colorado Springs) will determine from your laser specs whether or not your system presents a hazard to any satellites (some of them have very sensitive earth-looking sensors). Good luck & have fun. 73, John Albertine W3GFS ----- 09/20/96 I can't help thinking that the above (K3PGP: Refers to 1 KW pulsed ruby rod rig) might have some pretty serious consequences with regard to safety, which would make the use of such techniques very dangerous to others, and also yourself. Unless it could be done with a low power class I laser, (which perhaps it could, but I doubt it), I can't see how legally one can use a sufficiently powerful laser. Obviously if one used enough signal averaging, small signals can be detected. I use at work a lock in amplifier, that with suitable conditions can detect signals 100 dB + below the noise. The principle is to switch the laser on and off at say 1 KHz, then feed the detected signal to the lock in amp. Since the lock in amp is phase locked to the on/off switching of the laser, you can average enough pulses with the noise power increasing slower (root N) than the signal (N), so in principle you can increase the signal to noise ratio indefinitely, but not in practice. It would not be difficult to look at the feasibility of doing this. But getting a QSO using such procedures would be tiresome, but admittedly technically interesting. High power laser are I think are not feasible. One thing that people might like to note is that many of the simple diode laser pointers marked as class I, and therefor pretty safe are actually more powerful than the specs. The laser safety officer in the research department where I work has checked a number of these and found them to exceed the class I spec they quote. I assume they increase the power to make them work well, but put a class I sticker on them so they can be used for the purpose intended. David Kirkby G8WRB ----- K3PGP: 03/30/97 I will provide more notes as I run across them. I hope all of you enjoyed the comments from various stations and the brief history of laser EME. John K3PGP@juno.com -==- >From owner-laser Sun Mar 30 17:21:51 1997 Return-Path: Received: by berlioz.nsc.com (4.1/SMI-4.1) id AA23966; Sun, 30 Mar 97 17:21:51 PST To: laser@berlioz.nsc.com Date: Sun, 30 Mar 1997 20:22:14 -0500 Subject: 640x480 -43.jpg Pix File Message-Id: <19970330.202215.6454.0.K3PGP@juno.com> X-Mailer: Juno 1.23 X-Juno-Line-Breaks: 1-2,5-6,9-10,13-18 From: k3pgp@juno.com (John J. Yurek) Sender: owner-laser@berlioz.nsc.com Precedence: bulk To all that wondered what happened to the full size 640x480 -43db640.jpg picture file, it didn't make it through the reflector! By trying this I found out that this reflector apparently has an upper limit of 40,000 characters that it will accept as a valid message. Anything above that and it refuses to pass it on. However, Jim intercepted the file and says he will post in on the web site, so either look there if you want this or send Email to K3PGP@juno.com and I'll get a copy to you. Although I don't plan on making a habit of clogging everyone's Email box with graphic images, I will in the future do whatever is required to squeeze the file down to <40,000 bytes if the need should arise! John K3PGP@juno.com -==-