+++++++++++++++++++++++++++++ See also K2 Freq Calibrate C22-2 (Continuation of this file) +++++++++++++++++++++++++++++++ Subject: Re: [Elecraft] VCO Calibration All, > Because the K2 filters are so good, actually attempting to zero beat WWV > is quite problematic. It is much better to match beat tones. Let's say > you've got your side tone set to 680Hz. Then, if you listen to WWV with > the mode set for cw, when the beat tone from WWV matches your side tone, > the display ought to be close to 10000.00. If you use the L mode, when you > match the WWV beat tone to your side tone, the display ought to be close to > 10000.68. Exactly the way I ended up doing it. Mike VP8NO #1400 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ Subject: Re: [Elecraft] VCO Calibration For what it may be worth, my Zero Beating demo has been MOVED FROM my web site to the Elecraft Web Site, Builder's resource Page http://www.elecraft.com/Apps/zerobeat.htm. The demo includes two WAV files which are somewhat larger (300kB-500kB) than most other files there, so it'll take a little while to download them. 73 - Tom Hammond N0SS ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ Subject: Re: [Elecraft] VCO alignment K2'ers with VCO questions, It is better to have the VCO voltage near the upper limits, as it avoids the highly non-linear portion of the varactors when they are near minimum tuning voltage and maximum capacitance. That can cause some PLL linearization problems or erratic tuning, increased PLL tuning noise, etc. As long as you do not get too close to the 8 volt regulated limit, the higher the VCO voltage is - the better. Try to keep it below 7.0 to 7.5 volts at 4000kHz, to allow adequate high tuning range safety factor should the VCO voltage change slightly over time with component aging, etc. The VCO voltage is less than that value, on most any other band or frequency. A VCO setting 6 volts at 4000kHz is a good compromise, for consistent CAL PLL linearization and some limited general coverage receive range. If you aren't interested in out-of-ham band coverage, you can set the VCO voltage a little higher, at the 7.0 yo 7.5 volt range at 4000kHz. Be aware though, the higher the VCO voltage - the more restricted your out-of-ham band tuning will be in some cases on different bands. On some bands the VFO is added to the incoming signal to produce the IF, while on others it is subtracted. See the chart in the manual at the beginning of Appendix B to understand this. There is a "window" of VCO tuning voltage that is preferred, for complete ham band coverage and some limited SW general coverage. Several factors are at play here, so follow the suggested settings of VCO voltage as shown in the manual and do not set it either too low or too high for these reasons. 73, Gary Surrency AB7MY Elecraft Technical Support ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ Hi All, Just a note to say thanks to those who replied (many) to my problem with C22 not having enough range to align to my frequency counter. I was able to fix the problem by adding an 18 pF capacitor across the trimmer. I just mounted it on the under side of the control board. Now all is well in K2 land. Thanks for the suggestions and help. Regards, Jeff Weinberg W8CQ K2 #1617 w8cqjeff at ameritech.net +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ >The second part of my question, how would I know if I am zero beat with a >signal like WWV so I can use this signal to calibrate my K2's internal >frequency counter? Does this merely mean to tune for strongest received >signal? Tuning for the strongest received signal will probably NOT work... esp. for frequency calibration. WWV is kinda difficult to use for this type of adjustment because most of the time it transmits an audio tone (500Hz, I am told) AS WELL AS its normal carrier signal, so you MUST ensure that you are tuning to the CARRIER signal and not the audio tone. To do so properly, you tune in the WWV CARRIER such that the tone you hear from it is identical to the K2s sidetone (using the SPOT feature). When the two tones match, the frequency indicated on the display is that which the K2 'thinks' it's receiving on. Each time you tweak C22, remember to do another CAL PLL on 10MHz. This must be done or your tuning will not properly follow the changes made to C22. If my theory works right, I believe as you tune THRU the WWV signal, the first 'signal' you should hear will be that of the 500Hz tone they usually transmit... if you continue to tune further away from the signal, you should begin to hear a second signal. THIS should be the carrier and is what you want to match against your sidetone. There are certain times of each hour (maybe the last 5 minutes of the hour) where no tone is transmitted, just the carrier. This may prove easier to use, but since it lasts only a short while, it'll probably not be long enough for you to complete the adjustments. Hope this helps. 73 - Tom Hammond N0SS _____________________________________________________________ From: Stuart Rohre Subject: Re: [Elecraft] WWV tone sequences vary Actually, WWV has had charts in some of the ARRL Handbooks, (and probably on the NIST web site), showing the times they transmit various tones, including the note A, 440 Hz, of the musical scale. There is sub carrier modulation of a digi sort at some times, thus a full chart of each minute should be used to find when to listen for a carrier, or carrier and one tone or no tones,etc. 72, Stuart K5KVH +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ From: gsurrency at juno.com Subject: [Elecraft] RE: CAL C22 Hi K2'ers, Please note that when you replace the top cover with the speaker in it, the magnet influence on the frequency may be a considerable factor. Always set the top cover in place when you are trying to zero beat with WWV at 10MHz, and note the difference between the K2's LCD readout and the actual WWV frequency (10000.00kHz). Then you can remove the top cover to access C22 on the Control Board, run CAL FCTE and set C22 to compensate for the freq. readout error. Move C22 in the opposite direction of the freq. error from WWV, watching the change in CAL FCTR readout from its original reading. Replace the top cover, run CAL PLL again, and then see if you got C22 to the correct setting. Repeat this procedure as necessary until you are satisfied with the results. I noted as much as a 50Hz shift when I installed the top cover recently on a repaired rig *after* I thought I had C22 set perfectly. Had to do it all over again.......:-( Also remember that the bottom cover should be installed any time you are doing CAL PLL or CAL PLL. This will prevent the same kind of frequency shift and error if you forgot to do these calibrations with the covers off. 73, Gary Surrency AB7MY Elecraft Technical Support +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ The way I check the calibration is by tuning in WWV at 10 MHz on USB and LSB and centering the tuning so the tone being broadcast is the same (or within the 10 Hz resolution of the dial) on both sidebands. The CW BFO setting is then confirmed by hitting the SPOT button in CW mode and seeing that the sidetone is zero beat (within the same 10 Hz resolution) without changing the tuning dial. On mine, the calibration at 10 MHz moves about perhaps 20 or 30 Hz over many hours (or days) as the sun shines through the window, etc. In my experience, that is typical for a crystal-controlled oscillator that is not temperature-controlled oven. It is a 'very' slow movement. One time, in a frenzy of useless arm-waving, I recalibrated my K2 at 10 MHz using WWV because it was consistently a whole 20 Hz high. Got it right on. (If you do that, first measure how much taking the cover with the speaker off of your K2 changes the calibration. It does affect it. Gary Surrency reported that he found one that moved 50 Hz by removing the cover). It only took me a couple of hours to get it 'dead on' by the time I also rechecked all the BFO frequencies and got the uP to update all the settings for the filters. The next day I was 10 Hz low . I decided that it was more fun to operate the thing than to calibrate it! I guess that's why the tuning knob is right there on the front panel and C22 is buried under the crystal on the inside. ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ Got C22 set right now Thanks to STEVE, GARY, TOM, and others... HERE IS WHAT i DID set k2 to 10.000.00 lsb set up spectogram set offset tone for 440hz Turned on spot tuned k2 for zero beat on spot monitored spectogram and 440hz tone on wwv noted readout diffference from wwv on k2 used the internal counter and tp1 to offset freq ran cal pll ran cal fil on filter one (the one I was using) turned on spot and re-zero beated looked at spectogram to help me find zero beat made one more correction and repeated procedure the wwv zero beated at 10.000.00 on the k2 readout... the 440hz spot was directly over the 440hz wwv tone I turned the spectrogram calibration to .7 hz accuracy and re-checked the freq readout on the 440hz tone... from wwv I was less than 3hz off... no way to correct that when my receiver jumps in 10hz steps is there? I then followed the book procedure for the other bands and filters.. now 7.228 os 7.228 and 14.230 is 14.230 and 3.863 is 3.863 amazing what happens when one finally does something right... I don't think I will take the top off the k2 for a long time now...I've done caused myself enough grief... and now the grief - relief... meaux jeaux... I is on freq once meaux... ++++++++++++++++++++++++++++++++++++++++++++++++++++++++ Date: 11 Mar 2001 07:44:08 MST From: Murphy Chesney Subject: [Elecraft] re: Calibration question Vic - I had the same problem with C22, initially the K2 would calibrate using WWV 10MHZ right at the top of c22's capacity. Eventually though there was enough internal drift (after a year or so) so that I was 120 HZ off and couldn't get there with just c22. I finally put 47 pF across c22 and it gave me all the range I needed, so far without any bad side effects. Your milage may vary and I certainly wouln't go higher as the original c22 is just 50 pF. Let us know if you find a nifty way to get more range out of c22 since I prefer not to resort to "unauthorized" K2 mods!! 73's Sandy, KB3EOF K2 sn 904 +++++++++++++++++++++++++++++++++++++++++++++++++++++ Date: Mon, 12 Mar 2001 07:46:10 -0800 From: Vic Rosenthal Subject: Re: [Elecraft] re: Calibration question Murphy Chesney wrote: > Let us know if you find a nifty way to get more range out of c22 since I > prefer not to resort to "unauthorized" K2 mods!! Well...I spent the entire day and much of the night fiddling with c22, running CAL PLL and CAL FIL, fiddling some more, etc. I learned that you can move the range lower by adding a small capacitor across c22, you can move it higher by reducing the value of c21, and that the original parts were the right ones for me! The way I finally got it right was to match the pitch of the spot tone to wwv, and take the difference from 10 Mhz. Then I read the frequency of the VCO with the internal counter, subtracted the error, and changed c22 until the VCO showed the new value. Then I ran CAL PLL. When I checked wwv it was usually correct at this point; however, running CAL FIL threw it off a bit. So I repeated the process. After a few iterations, it came out right, and then I ran CAL PLL on all of the bands. Now my K2 is within 10 or 20 Hz of my TS850 in most places (and spot on with wwv at 10 Mhz). And I'm bloody tired of c22! 73, Vic, K2VCO Fresno CA ++++++++++++++++++++++++++++++++++++++++++++++++++++++ Date: Mon, 12 Mar 2001 20:00:51 -0800 From: "Ron D'Eau Claire" Subject: RE: [Elecraft] re: Calibration question Vic, K2VCO wrote: "Now my K2 is within 10 or 20 Hz of my TS850 in most places (and spot on with wwv at 10 Mhz). And I'm bloody tired of c22!" Brings back memories for me and a bunch of readers, I'm sure, Vic. There was a time I didn't get on the air for several sessions at the rig, between fiddling with the calibration of the dial and using Spectrogram on the filters. Almost considered welding the case shut so I could get in one uninterrupted operating session! You did *very* well getting that close, since the DAC's used in the K2 introduce a built in 20 or 30 Hz error that can't be 'tuned out' on purpose. Ron AC7AC K2 # 1289 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++ Date: Sat, 30 Jun 2001 17:14:39 -0500 From: Tom Hammond =?iso-8859-1?Q?N=D8SS?= Subject: Re: [Elecraft] Bad Crystal? Alan: >Per page 57 in the K2 manual, I can't adjust C22 to match my external >frequency counter. I can only get within 120 kHz or so. Do I have a >bad crystal or bad C22? Not unheard of... Determine whether your C22 is fully OPEN or fully closed and add a little padding capacitance across C22 or C21, depending upon which way you need to go with C22. Or... you can change C21 to compensate if you don't wish to 'pad'. 73 - Tom N0SS +++++++++++++++++++++++++++++++ Date: Sat, 30 Jun 2001 20:35:32 -0700 From: Vic Rosenthal Subject: Re: [Elecraft] Bad Crystal? Alan Price wrote: > > Hi: > > Per page 57 in the K2 manual, I can't adjust C22 to match my external > frequency counter. I can only get within 120 kHz or so. Do I have a > bad crystal or bad C22? Do you mean 120 KHz or 120 Hz? Rotate your C22 all the way around a few times and see if that helps. Also, are you sure your counter is correct? You can do as well adjusting C22 by zero-beating WWV. 73, Vic, K2VCO Fresno CA ++++++++++++++++++++++++++++++++++ Date: Sat, 08 Sep 2001 22:27:42 +0000 From: Steven Gibbs Subject: [Elecraft] K2 freq set - high accuracy method If you have access to a 1MHz frequency standard, here's a method of setting the K2's reference oscillator with greater certainty than trying to zero-beat with WWV. I used an off-the-air standard derived from the high-accuracy carrier frequency of the BBC's 198kHz LW transmission; I believe that some GPS receivers provide a standard 1MHz output. You will need a 4MHz bandwidth oscilloscope having a high-sensitivity x-amp (5mV/div worked for me), with an independent trigger input derived from your frequency standard. 1. Temporarily reduce the x-amp sensitivity, connect to the trigger source, and adjust the 'scope's timebase and trigger level to stably display one or two cycles of the 1MHz standard frequency. 2. Move the 'scope probe to the vicinity of X2-C21-C22 on the K2 control board, but do not touch anything, just rely on loose capacitive coupling. Connect the probe's ground connection to the control board ground point. Switch the 'scope to maximum x-sensitivity, and look for a trace showing pick-up from the 4MHz clock oscillator. 3. Use a non-metallic trimming tool (sorry, but the Elecraft tool is pretty useless here) to carefully adjust C22 so that the scope trace is resolved into a sine wave moving slowly or rapidly either to the left or to the right. Note that four cycles occupy the same time as one cycle of the 1MHz reference oscillator. Careful tuning will result in a near-stationary display when the trimming tool is removed, and the 'scope probe is gradually drawn away. This indicates very close matching of the K2's reference oscillator to four times the standard frequency. (A left or right shift of 4 cycles in one second means the frequencies are matched to one part in a million. Temperature effects will degrade frequency accuracy, so it's probably not worthwhile trying for better than this). 4. Remember that control board reference oscillator X2 does NOT directly control K2's TX & RX frequencies. You will have to re-perform CAL PLL & CAL FIL. 4. Connect the K2 frequency counter probe to TP1 and perform CAL PLL (do this on each band if you have version 1 firmware). 5. Connect the counter probe to TP2 and run through all the CAL FIL parameters. You may not have to change anything, but it is necesssay for the firmware to recognise and remember any apparent change in BFO frequency. (Just to satisfy yourself, you might want to connect up to a computer running the Spectrogram program to re-check that everything is OK). That's all folks. 73, Steve GU3MBS +++++++++++++++++++++++++ Date: Sun, 09 Sep 2001 00:08:11 -0400 From: Jared Smith Subject: Re: [Elecraft] K2 freq set - high accuracy method Seems like a good method. But zero beating WWV is very easy with the use of the Spectrogram program and knowledge of the WWV broadcast tones. WWV broadcasts alternating minutes of 500 Hz. tones and 600 Hz. tones - -- real easy to zero in on with Spectrogram to about +/- 2 Hz. I've been able to get calibration accuracy below 20 Hz. using these tones as a zero beat guide. I think that's about as good as you can do on a K2. You can find more info about the WWV tones at www.bldrdoc.gov/timefreq/stations/iform.html. Anyone have any other ideas? Rich W1EZ K2#1763 Steven Gibbs wrote: >If you have access to a 1MHz frequency standard, here's a method of >setting the K2's reference oscillator with greater certainty than >trying to zero-beat with WWV. --- snip --- +++++++++++++++++++++++++ Date: Mon, 10 Sep 2001 10:03:25 -0100 From: "Julian, G4ILO" Subject: Re: [Elecraft] K2 freq set - high accuracy method Unfortunately, I'd guess that the majority of K2 builders don't have access to the needed test equipment, in which case they have little alternative but to "zero in using Spectrogram amongst the crud which surrounds the carriers of standard frequency broadcasts." Of course, they may decide not to bother at all since due to the way the K2 firmware interpolates frequency steps and the fact that the K2 reference oscillator isn't a TCXO I doubt if calibration is maintained all the time across all bands to more than 50Hz or so anyway. - -- Julian, G4ILO. (RSGB, ARRL, K2 #392) Homepage: http://www.qsl.net/g4ilo Steven Gibbs wrote: My posting wasn't intended to claim the method was "more accurate" than others, just that the adjustment could be made "with greater certainty" (=confidence), provided the needed test equipment is available. [snip] ++++++++++++++++++++ Date: Tue, 23 Apr 2002 07:36:25 -0700 From: Vic Rosenthal Organization: Transparent Software To: Elecraft Subject: Re: [Elecraft] K2 #2555 on air! couple of questions... Andreas Hofmann wrote: > > When I change C22 on the control board, nothing changes on my frequency > display at all. According to manual page 57, I should be able to change > the Oscillator calibration by changing C22. > > Steps I did: > I have the frequency counter probe connected to TP3. > Switched to LSB. > I found the WWV signal at 10,000.51 ( I guess it is supposed to be at > exactly 10,000.00) > > Should I desolder C22? No! What you need to do is note how much WWV appears to be off (you are + 510 Hz). Connect the probe to TP1, switch to CAL FCTR and adjust C22 until the reading is 510 Hz LESS than it was before. Then do CAL PLL and CAL FIL again. You MUST rerun these procedures after changing C22 to see the changes. Then look at WWV again -- you should be closer. You might have to do this more than once. 73, Vic, K2VCO Fresno CA ++++++++++++++ Subject: RE: [Elecraft] K2 #2555 on air! couple of questions... Date: Tue, 23 Apr 2002 21:19:06 -0700 From: "Andreas Hofmann" To: "Vic Rosenthal" Cc: Thanks, that did it (got it down exactly to 10,000.00, also the beacons are now exactly at 14,100.00). =20 I don't think the manual mentions the fact that one needs to re-run CAL PLL. Thanks for that hint. 73 DL6UST/W7 Andreas > -----Original Message----- > From: Vic Rosenthal [mailto:rakefet at rakefet.com] > Sent: Tuesday, April 23, 2002 7:36 AM > To: Andreas Hofmann > Subject: Re: [Elecraft] K2 #2555 on air! couple of questions... >=20 > Andreas Hofmann wrote: > > > > When I change C22 on the control board, nothing changes on my frequency > > display at all. According to manual page 57, I should be able to change > > the Oscillator calibration by changing C22. > > > > Steps I did: > > I have the frequency counter probe connected to TP3. > > Switched to LSB. > > I found the WWV signal at 10,000.51 ( I guess it is supposed to be at > > exactly 10,000.00) > > > > Should I desolder C22? ++++++++++++++++ From: "Rich Lentz" To: "'Dave Johnson'" , Cc: Subject: RE: [Elecraft] K2 Frequency calibration Date: Thu, 25 Apr 2002 17:34:19 -0500 The National Physical Laboratory http://www.npl.co.uk/npl/ctm/time_trans.html Includes just about all frequency/time standards of any importance. Should be able to find one that that you can hear in Europe and also serve as a propagation indicator. Rich KE0X >Anybody recommend a known reference transmission in the K2 tuning range for us >in Europe? ++++++++++++++++++ Date: Fri, 31 May 2002 22:45:52 -0400 From: frastephen at comcast.net To: elecraft at mailman.qth.net Subject: [Elecraft] Usnig Spectrogram for Zero-Beating WWV, Frequency Calibration, and Filters K2 #2644 continues to be aligned! There is serious lightning here in the Philly area right now, so #2644 is disconnected from everything! Hence, a good time to send along some insights I had this evening. Maybe this is old hat to everybody, but I am pleased I figured this out and maybe it might help someone else. Well, I wanted to calibrate the frequency of the VFO and align the filters. So I downloaded Spectrogram (and registered it! I used to be a programmer in a previous life and I liked to eat, too!) and used it with N0SS's wonderful instructions from the Elecraft web site for aligning the filters. What a really great program (although, I wish the audio sent into the MIC was also patched out to the speakers so you could listen to the audio as well as watch it!). I then realized I had not done anything to calibrate the frequency of the VFO! Oops! Well, then I got an interesting idea ... why not use Spectrogram to get a really close zero-beat of WWV? You might remember that WWV sends precision audio tones of various frequencies along with a 1000Hz "tick" each second (details on their web site). So I hooked it back up and Spectrogram gave a really great display of these various tones and I was able to get a really great zero-beat of WWV, which I used to ultimately do the adjustment to C22 for the 4 MHz Oscillator calibration (using the instructions from the Elecraft website). It took a few iterations of the procedure (I believe, three), but in the end I believe I have the frequency calibrated to within 10 Hz (theoretically, I see from the Specifications on p. 5 of the manual that the VFO accuracy is +/- 30 Hz). Not bad!!!! Probably as good as you can get. Then I used N0SS's instructions to do the alignment of the filters. Then I got another insight! Why not use Spectrogram to verify and make fine tuning adjustments to the filters with a strong signal on a known frequency.... So back to Spectrogram and I used it to monitor the audio from a certain signal at 7047.5 kHz. W1AW was blasting away, as usual here. With the frequency display calibrated I could tune it in right on the money (although I have seen some posts about W1AW not being exactly WWV when it comes to frequency stability -- never noticed it myself). So I used that steady signal to fine tune the filters exactly where I wanted them in the audio spectrum across all four filters (8 actually, counting the CW RV settings). Nice strong peaks at 600 Hz right across the board without tuning the VFO -- a steady tone across all the filters. Bottom Lines: I got everything aligned quite well! I learned a lot about how the K2 VFO and filters work! I learned a lot about Spectrogram! A worthy evening, if I do say so myself! Fun and educational! Well, the lightning has passed .... Peace and 73, Stephen W3SMK K2 #2644 ++++++++++++++++++ From: "Don Brown" To: "Elecraft" Subject: Re: [Elecraft] Frequency calibration Date: Thu, 20 Jun 2002 11:05:07 -0500 Hi I set up a marker at 500 and 600 Hz in Spectrogram. Then adjust the k2 so= the WWV 500 and 600 Hz tones are centered on the markers. The markers ar= e on most alternate minutes. Then read the K2 display and see how much it= is off. Adjust the 4 MHZ master clock on the control board by the same a= mount as the error as described in the manual. Then do the PLL calibratio= n and recheck WWV with Spectrogram. You may have to do this procedure sev= eral times to get it perfect. Don Brown KD5NDB ----- Original Message ----- From: kevinrock at earthlink.net Sent: Thursday, June 20, 2002 10:53 AM To: elecraft at mailman.qth.net Subject: [Elecraft] Frequency calibration Howdy group, Does anyone have a procedure written up for calibrating the frequency = on the K2 using Spectrogram? I have used this software to tune my CW and SSB filters but I would like to use it to get = my K2's frequency readings a little closer to what they should read. Kevin ++++++++++++++++++++ To: lhlousek at nvbell.net, elecraft at mailman.qth.net Date: Tue, 16 Jul 2002 10:37:37 -0700 From: k6se at juno.com Subject: [Elecraft] K2 Alignment Hi, Lou, If your K2's VFO is accurate on some bands and not accurate on others, it might be that you detuned the 4 MHz oscillator to make the VFO read more accurately on, say 10 MHz WWV. The 4 MHz oscillator should be set precisely to 4000.000 kHz and never be touched again. Do a CAL PLL after setting the oscillator to 4000.000 kHz and accept whatever small dial readout error there is on WWV. To eliminate the pitch change on CW when you change filters, use the following procedure: When doing CAL FIL (and before tuning in an alignment signal - i.e., use background noise), use Spectrogram to center all CW filters (CWN and CWR) at the pitch you have your sidetone set to. Setting a marker in Spectrogram at this audio frequency will help you to visually center the passbands. Select the narrowest CW filter (FL4) and tune in a steady signal (such as the 7 MHz birdie) using the VFO knob so that the signal is peaked in the center on the passband display on Spectrogam, i.e., at the sidetone frequency marker. Never touch the VFO knob again during this alignment procedure. Select the next-widest CW filter (FL3) and if the signal is not at the same tone as above (aligned with the sidetone frequency marker), adjust the BFO to align it with the marker (i.e., the same tone as in the narrowest filter). Repeat the above paragraph for FL2 and FL1 in that order. Repeat all of the above steps for the other CW sideband. Do a CAL PLL. The main object is to use FL4 (the narrowest filter) when tuning in a signal and use it as your "reference" when calibrating the BFO for the other CW bandwidths. When completed, you'll find that the CW pitch does not change when selecting a different filter nor does it change whan you switch to the opposite CW sideband. Actually, the widest three CW filters may be aligned in any order so long as the signal is tuned in to be centered in the passband while using the narrowest filter. Hope this helps. 73, de Earl, K6SE +++++++++++++++++++++ From: "Dan Barker" To: "Elecraft" Subject: FW: [Elecraft] 4 MHz alignment Date: Thu, 18 Jul 2002 15:40:48 -0400 Sounds like you are trying to zero beat two tones of approximately 0 Hz. That can't be done. Regardless of the low-freq rolloff in the various audio chains, you can't hear below 20 Hz or so. Try to zero-beat up around 600 Hz, where the audio chain and the ears work fine. So, a WWV signal 10000000.000 Hz detected by BFO freq of 10000600.000 makes a 600 Hz audio tone. If the other signal is at 10000000.125 and about the same volume, you'll hear the 600 Hz tone ebb and wane once every 8 seconds. Nobody can hear 1/8 Hz, but most of us can hear 600 Hz, and notice the volume going up and down. Dan / WG4S / K2 #2456 I repeated the procedure with good headphones and was able to lower the frequency of the beat. [Hey, shouldn't this be ?] ++++++++++++++++++ From: kevinrock at earthlink.net To: "Elecraft" , "Dan Barker" Date: Thu, 18 Jul 2002 13:51:10 -0600 Subject: Re: FW: [Elecraft] 4 MHz alignment I am just following the procedure on page 57 of the K2 assembly manual. Others on this reflector have mildly condemned the use of WWV since it is unrelated to the 4 MHz frequency the VFO uses. If WWV transmitted at 4 MHz your suggestion would work quite well. As it is I need to adjust C22 for the best 4 MHz signal I can find. Try this it works pretty well. I am in the process of testing my results now. Kevin. 7/18/2002 1:40:48 PM, "Dan Barker" wrote: >Sounds like you are trying to zero beat two tones of approximately 0 Hz. >That can't be done. Regardless of the low-freq rolloff in the various audio >chains, you can't hear below 20 Hz or so. > >Try to zero-beat up around 600 Hz, where the audio chain and the ears work >fine. > >So, a WWV signal 10000000.000 Hz detected by BFO freq of 10000600.000 makes >a 600 Hz audio tone. If the other signal is at 10000000.125 and about the >same volume, you'll hear the 600 Hz tone ebb and wane once every 8 seconds. >Nobody can hear 1/8 Hz, but most of us can hear 600 Hz, and notice the >volume going up and down. > >Dan / WG4S / K2 #2456 > > I repeated the procedure with good headphones and was able to lower >the frequency of the beat. [Hey, shouldn't this be ?] +++++++++++++++++ +++++++++++++++++++ Date: Thu, 18 Jul 2002 17:23:52 -0500 To: kevinrock at earthlink.net, elecraft at mailman.qth.net From: "Timothy A. Raymer" Subject: Re: [Elecraft] 4 MHz alignment Kevin, If you have an Oscilliscope, you can clip it on the audio output, and see the zero beat. What you will be looking for is a very slow change in the amplitude of the waveform. Hope this helps a bit. Tim Raymer 73 de KA00UV K2 #1383 +++++++++++++++++++ From: "Rich Lentz" To: "'Timothy A. Raymer'" , , Subject: RE: [Elecraft] 4 MHz alignment Date: Thu, 18 Jul 2002 17:59:28 -0500 If You don't have an O'scope, you can use Spectrogram, or any of the other programs that display audio signals on the PC. There was a recent posting (Early July) for a simple free Zero beat waterfall type program on this group. Rich, KE0X -----Original Message----- If you have an Oscilloscope, you can clip it on the audio output, and see the zero beat. -- snip -- ++++++++++++++++++++ From: "Lyle Johnson" To: Subject: RE: [Elecraft] 4 MHz alignment Date: Thu, 18 Jul 2002 16:25:24 -0700 Sorry, I have to jump in on this one. Please keep in mind that the display on the K2, though showing a RESOLUTION of 10 Hz, does not mean that it is ACCURATE to 10 Hz. As another poster mentioned, there is some frequency drift with time and temperature. But having the 10 Hz steps enables you to fine tune the other station, even if the steps are really 9.998 Hz. As long as you get the 4 MHz oscillator "close," you will be operating "close enough." If you don't operate within 100 Hz of a band edge on 10 meters (don't forget your sidebands!), then getting within 15 or 20 Hz at 4 MHz will be sufficiently accurate. If you stay at least 1 kHz from the edge on 10m, then you only need to be within 150 Hz or so at 4 MHz. If you are using a receiver to "tune for zero beat" don't forget that the receiver may not be more accurate than 100 Hz or so. Depending on the receiver, it may be a lot more than 100 Hz off! If you are using a frequency counter, just because it says you are at 4.00000000 MHz doesn't mean you are! When was the last time you calibrated its timebase? What did you use? And if it is a bargain counter, it probably isn't nearly as accurate as its number of display digits would lead you to believe. I bought a new HP frequency counter a few years ago and used it as my shack reference. (Hey! It's HP! They're conservative...) Last year I got a GPS-stabilized master oscillator and a Rubidium standard as well. I found my HP 10 MHz timebase was off quite a few Hz. We all have a tendency to believe the readings of our test equipment, assume our radios are calibrated accurately, etc. I have heard far too many QSOs where the operators are comparing their dial readings and trying to decide who is on frequency and who is not. (My radio is more expensive than yours and newer besides, so I'm on frequency and YOU have to QSY to get on the proper NET frequency! I'm not budging...) The bottom line: as long as you aren't outside the band edge, you are legal. If you can tell the other station to QSY up 15 kHz and find each other, you are accurate enough, IMHO. So get the 4 MHz as close as you can and don't worry about it :-) Enjoy! Lyle KK7P ++++++++++++++++++ To: kevinrock at earthlink.net, elecraft at mailman.qth.net Date: Thu, 18 Jul 2002 17:37:16 -0700 Subject: Re: [Elecraft] 4 MHz alignment From: k6se at juno.com kevinrock at earthlink.net wrote: "Since I do not have a frequency counter I am attempting to adjust C22 using my Icom 706 and zero beating. The zero beat area is quite broad so I am wondering if this method is as accurate as the third technique of using Spectrum whilw receiving WWV. I have a test lead from the SO 239 on the Icom laid across the XTL on the control board. I am adjusting C22 with a metal screw driver and achieving a zero beat as if I was tuning a guitar. The frequency probe is plugged into P6 and TP3. The CAL FCTR menu choice is set. But it appears much less sensitive than while tuning against WWV using the technique in the assembly manual or the technique of using Spectrum. Is there something wrong with my technique or should I just find a frequency counter somewhere and use it to allay my doubts?" ========== If your Icom 706 is accurate on 5 MHz WWV (or 10 MHz WWV), then using your 706 receiver on 4000.00 kHz will be more accurate for setting the 4 MHz oscillator than by using Spectrogram and WWV. To check your 706's accuracy, tune WWV in while the 706 is in the SSB mode. During the first 30 seconds after most time announcements, WWV transmits a constant audio tone. During this tone, switch the 706 between USB and LSB and tune the signal so that you hear no pitch change in the tone on either sideband. Doing that, you have exactly zero-beat WWV, and you can look at the frequency readout on your 706 to see how close it is. If the dial is not precisely accurate, there might be an adjustment in your 706 to set its oscillator more accurately. This info might be in the 706 manual. Anyway, if your 706's frequency readout is accurate on WWV, you can use the 706 as you have been doing to listen to the K2's 4 MHz oscillator. It's not necessary to have the K2's freq probe in TP3 (in fact, it's advisable not to because the probe in TP3 pulls the PLL reference oscillator slightly) nor is it necessary to have the K2 in the CAL FCTR mode. Set your 706 to 4000.00 kHz in either USB or LSB mode and adjust C22 on the K2's control board so that the K2's 4 MHz oscillator is zero beat in your 706 as closely as you can determine. Switching between USB and LSB on the 706 might help determining zero beat, but there's no audio tone on the K2's 4 MHz oscillator, so zero-beat cannot be determined as accurately as it can be with WWV. Now, after you have the K2's 4 MHZ oscillator zeroed on 4000.00 kHz as closely as your ear can determine, switch your 706 to the CW mode. Adjust the VFO on the 706 so than the K2's 4 MHZ oscillator is heard at the same pitch that you have your 706 set up for on CW. The frequency readout on your 706 shoulld read exactly 4000.00 kHz if you have the K2's 4 MHz oscillator set correctly, even though the signal is not "zero-beat" in your 706 on the CW mode, i.e., you'll hear a 600 Hz or 800 Hz tone, i.e., equal to the offset frequency your 706 CW pitch is set to. You also should be able to switch between CW-USB and CW-LSB on your 706 and the pitch of the received signal (the 4 MHz oscillator) should not change, nor should the 706's frequency readout change (assuming the 706 is like most modern receivers). Be sure to do a CAL PLL after adjusting C22. Compared to using an external frequency counter, the foregoing method can easily be more accurate if the frequency counter has not been recently calibrated. This all may sound complicated, but the procedure is quite easy to do and is quite accurate. 73, de Earl, K6SE +++++++++++++++++ Date: Fri, 29 Nov 2002 14:20:10 +0000 To: Ron Willcocks , Elecraft From: Steven Gibbs Subject: Re: [Elecraft] 4mhz osc and Firmware change. Hi Ron, try this ... 1. Set the K2 to about 9999.00kHZ USB. On Spectrogram you should see the WWV 10MHz carrier as a tone of about 1000Hz. Ignore any tones WWV might be transmitting. 2. Disconnect the antenna; you should see a weak signal also of about 1000HZ - this is the tenth harmonic of a 1MHz signal derived by the MCU from its 4MHz clock (you will recall that a similarly-derived 7MHz signal is used in initial 40M alignment). You can verify that you are looking at the right signal by touching the Control Board MCU crystal X2 or its associated components and noting that the frequency on the Spectrogram display changes slightly. 3. If WWV is coming through strongly there might be enough breakthrough to show WWV's signal also. Use an insulated tuning tool (the Elecraft tool is rather poor for this job) to adjust Control Board C22 so that the two signals coincide - final proximity may show a beat which can be reduced to zero. If WWV isn't very strong you won't see its breakthrough signal so you'll have to alternately connect and disconnect the antenna until you have the two signals giving the same frequency on spectrogram. 4. Note that the exact setting of the K2 dial and the exact frequency on the Spectrogram display doesn't matter. (The sidetone frequency which you use doesn't matter either). These are the important features of this method. 5. It's a good idea to re-perform CAL-FIL. 6. You must re-perform CAL-PLL. 7. SPOT the WWV carrier in CW and again in CW-REV; in each case the K2 dial should show 10000.00kHz probably plus or minus about 20Hz. 8. If you have a local frequency standard there's a method of setting the MCU frequency with even more certainty - my posting of 8 Sep 01, reproduced below. 73, Steve GU3MBS ==== If you have access to a 1MHz frequency standard, here's a method of setting the K2's reference oscillator with greater certainty than trying to zero-beat with WWV. I used an off-the-air standard derived from the high-accuracy carrier frequency of the BBC's 198kHz LW transmission. You will need a 4MHz bandwidth oscilloscope having a high-sensitivity x-amp (5mV/div worked for me), with an independent trigger input derived from your frequency standard. 1. Temporarily reduce the x-amp sensitivity, connect to the trigger source, and adjust the 'scope's timebase and trigger level to stably display one or two cycles of the 1MHz standard frequency. 2. Move the 'scope probe to the vicinity of X2-C21-C22 on the K2 control board, but do not touch anything, just rely on loose capacitive coupling. Connect the probe's ground connection to the control board ground point. Switch the 'scope to maximum x-sensitivity, and look for a trace showing pick-up from the 4MHz clock oscillator. 3. Use a non-metallic trimming tool (sorry, but the Elecraft tool is pretty useless here) to carefully adjust C22 so that the scope trace is resolved into a sine wave moving slowly or rapidly either to the left or to the right. Note that four cycles occupy the same time as one cycle of the 1MHz reference oscillator. Careful tuning will result in a near-stationary display when the trimming tool is removed, and the 'scope probe is gradually drawn away. This indicates very close matching of the K2's reference oscillator to four times the standard frequency. (A left or right shift of 4 cycles in one second means the frequencies are matched to one part in a million. Temperature effects will degrade frequency accuracy, so it's probably not worthwhile trying for better than this). 4. Remember that control board reference oscillator X2 does NOT directly control K2's TX & RX frequencies. You will have to re-perform CAL PLL & CAL FIL. 4. Connect the K2 frequency counter probe to TP1 and perform CAL PLL (do this on each band if you have version 1 firmware). 5. Connect the counter probe to TP2 and run through all the CAL FIL parameters. You may not have to change anything, but it is necesssay for the firmware to recognise and remember any apparent change in BFO frequency. (Just to satisfy yourself, you might want to connect up to a computer running the Spectrogram program to re-check that everything is OK). That's all folks. 73, Steve GU3MBS ++++++++++++++ From: "Rich Lentz" To: "'Steven Gibbs'" , "'Elecraft'" Subject: RE: [Elecraft] 4mhz osc and Firmware change. Date: Fri, 29 Nov 2002 13:56:11 -0600 Steve: Thanks! This works! On the second iteration got WWV within 10 Hz. Close enough. And much easier than many of the other methods posted here. Rich KE0X +++++++++++++++