+++++++++++++++++++ K2 Rev B Specific Build Notes See also K2 Rev B Build Notes2 +++++++++++++++++++ Date: Fri, 08 Nov 2002 21:03:02 -0800 From: Wayne Burdick Organization: Elecraft To: David Schornak Cc: Elecraft Subject: [Elecraft] Re: L25 L26 David Schornak wrote: > L25 L26 > in the old manual it says both get wound on the red cores with 16 turns > in the manual that came with my k2 rev b it says to wind 13 on one and 14 on the other I was wondering which is correct I am assuming that the manual that came with my rev b board should be right. Hi David, The new manual is correct for your Rev B K2 kit. The original 40-meter low-pass filter has been redesigned to improve roll-off of the second harmonic when operating on 60 meters, in anticipation of the future K60XV option (60 meters + low-level transverter I/O). The original 40-meter filter suppresed the 2nd harmonic on 60 meters to an acceptible degree (about -50 dB), but the new one is about 10-15 dB better. 73, Wayne +++++++++++++++ From: "Don Brown" To: "David Schornak" , "Elecraft" Subject: Re: [Elecraft] bfo testpage 59 Date: Sat, 9 Nov 2002 10:26:14 -0600 Hi I had a K2 with a narrow BFO range and the problem was a bad Q24. You could carefully remove Q6 or Q7 on the control board and install it in place of Q24 to see if this fixes the BFO, if so then the transistor is bad and order another one. Q6 and Q7 on the control board are for audio muting so you don't need them for this test. Double check all of the parts in the BFO circuit making sure the varactor diodes and crystals are the correct ones. The filter crystals and the BFO crystals are different even though they are marked with the same frequency, make sure you did not mix them up. Don Brown KD5NDB ----- Original Message ----- From: "David Schornak" To: "Elecraft" Sent: Saturday, November 09, 2002 9:50 AM Subject: [Elecraft] bfo testpage 59 bfo test initial reading 4916 hi 4916.92 low 4913.48 difference it 3.44 no my 4 mz oscillator calibration has not been set as I don't have anther receiver handy or a frequency counter that is handy I have checked all the components in the bfo but to no avail my difference still is not >=3.6 what can I do? or what should I do. see ya 73's KG4LSK David Schornak K2 03027 ++++++++++++++ Date: Fri, 15 Nov 2002 09:42:36 -0800 From: Wayne Burdick Organization: Elecraft To: Elecraft Subject: [Elecraft] K2 Builder Alert: R19 on RF board wrong value K2 BUILDER ALERT #18: R19 on RF board is the wrong value Applicability This builder alert applies to: - new K2s with serial numbers from 3000-3055 - older K2s that have been updated with the BFO/PLL mod kit, if a value of 220 ohms was used for R19 Background Resistor R19, on the RF board, was recently added to the design. It extends the tuning range of the PLL reference oscillator to make it easier to cover the required range with a single crystal. The value of R19 should have been between 1.8 and 3.3 k, but 220 ohms was supplied. This smaller value can result in VFO tuning non-linearities of as much as 70 Hz at certain points in the VFO tuning range. We strongly recommend replacing R19 with a larger value as described below. Change Required 1. Replace R19 with an ordinary carbon-composition or carbon-film resistor between 1.8 k and 3.3 k (any power rating, any tolerance). On the Revision B RF board, R19 is located on the bottom of the board near the PLL reference oscillator crystals. There is no R19 on earlier K2 RF boards. But if you removed one PLL reference oscillator crystal as part of a temperature-stability mod, you may have added R19 to the board (soldered between pins 7 and 8 of RP2). NOTE: The resistor's power rating can be anything from 1/10th watt or higher, but use a resistor that will fit on the bottom of the RF board without interfering with the bottom cover. Do not use a wire-wound resistor. If you do not have a suitable resistor, you may request one from Elecraft by sending e-mail to parts at elecraft.com. Ask for Elecraft part number E500005 (2.7 k, 1/4 watt). 2. Re-run CAL PLL. If you have revision 2.XX K2 firmware, CAL PLL is to be done only on 40 meters. If you have 1.XX firmware, CAL PLL must be run on all bands. In either case, refer to your K2 manual or the application note you used when adding R19 to the board. 3. Note this change on the K2 schematic (RF board, sheet 1). +++++++++++++++ Date: Fri, 15 Nov 2002 15:51:28 -0800 From: Wayne Burdick Organization: Elecraft To: james-e-hammons at worldnet.att.net Cc: elecraft at mailman.qth.net Subject: [Elecraft] Re: K2 Builder Alert: R19 on RF board wrong value James Hammons wrote: > Seems to me, if you have enough range without the added R19 it > would be better to leave it at 10k. Even if you have enough reference oscillator tuning range without adding R19, you might still want to add it. It will allow you to tune significantly below 160 meters (into the AM band) while preserving VFO tuning linearity. The high end of the AM band is an interesting place -- try listening at night! > With the BFO now showing less drift than the PLL ref osc, I am > wondering if could not also be improved a little bit more using a > toroid on a T44-7 core like the BFO? In nearly all cases, the answer would be no. The inductor used in the reference oscillator already has a decent temperature coefficient, and the drift here is dominated by the varactor diodes. In fact we tried this and found that the higher Q of a toroid at this location could actually be detrimental. We're testing some special capacitors (N750) which may provide a slight additional improvement. We'll post results once we've tried them. 73, Wayne N6KR +++++++++++++++++++ From: "Don Brown" To: "David Schornak" , "Elecraft" Subject: Re: [Elecraft] kio2 mods to control board Date: Sat, 16 Nov 2002 12:05:24 -0600 Hi No the control board has all of the mods incorporated into the board. Including the KIO2 mod, sine wave side tone, noisy audio gain pot mod and AGC threshold. In addition there is better filtering on several control lines. Don Brown KD5NDB ----- Original Message ----- From: "David Schornak" To: "Elecraft" Sent: Saturday, November 16, 2002 11:56 AM Subject: [Elecraft] kio2 mods to control board if you have the rev b k2 do you still have to cut a trace and solder a cap in on the control board for the kio2 board to work or is it just plug and play now see ya 73's KG4LSK David Schornak K2 03027 ++++++++++++++++++ Date: Sat, 23 Nov 2002 20:47:17 -0800 From: Wayne Burdick Organization: Elecraft To: N0SA Cc: elecraft at mailman.qth.net Subject: Re: [Elecraft] BFO test?? Larry, We discovered recently that some of the BFO crystals, from a new manufacturing lot, had higher Q than usual. You apparently received one of these sets, even though we've tried to pull them all out of stock. The high-Q crystals will work very well, but you'll need to increase the capacitance of C174 and C173 to get another few hundred Hz or so of range. We have already solved the problem this way in two cases that I know of. All you need is a capacitor in the range of 39-68 pF to parallel across C174, and one in the range of 100-180 pF to parallel across C173. The capacitors should be of a stable type (NPO or C0G or N750; disc, mono, S.M., polystyrene, etc.). If you don't have a couple of usable caps laying around, send e-mail to parts at elecraft.com and we'll get them out to you. Sorry for the inconvenience. 73, Wayne N6KR N0SA wrote: > > I am doing the BFO test on my new K2 #3045. I get a swing of only 3.22Khz. I have checked all the parts in the bfo, L33 D37, D38 ,caps etc and have checked the 4Mhz osc for calibration. I can find nothing wrong. Anyone have any suggestions? +++++++++++++++ Date: Tue, 26 Nov 2002 10:02:27 -0800 From: Wayne Burdick Organization: Elecraft To: Nate Lewis Cc: elecraft at mailman.qth.net Subject: [Elecraft] Re: BFO test?? Yes. Actually, Nate, you're close enough to continue with all BFO alignment steps. But we like to have a bit of a margin on both ends, so try the caps if you have them available. 73, Wayne Nate Lewis wrote: > > #3051: > BFO high freq: 4917.10 (must be >= 4916.3 kHz) > BFO Low Freq: 4912.94 (must be <= 4912.7 kHz) > > same fix? > > ----- Original Message ----- > From: "Wayne Burdick" > To: "N0SA" > Cc: > Sent: Saturday, November 23, 2002 8:47 PM > Subject: Re: [Elecraft] BFO test?? > > > Larry, > > > > We discovered recently that some of the BFO crystals, from a new > manufacturing > > lot, had higher Q than usual. You apparently received one of these sets, > even > > though we've tried to pull them all out of stock. -- snip -- ++++++++++++++ Date: Mon, 02 Dec 2002 16:21:19 -0800 From: Wayne Burdick Organization: Elecraft To: Elecraft Subject: [Elecraft] Builder Alert #19: current metering (C42 and C44) APPLICABILITY Revision A and XC K2s: ALL Revision B K2s: Serial Numbers 3000-3077 BACKGROUND This builder alert replaces alert #17 -- PLEASE READ. Builder alert #17 had recommended the addition of C44 (0.1 uF) to the Control board on older K2s. This capacitor is also present on the revision B K2. Based on further testing and field reports, we have determined that C44 should NOT be used. In some cases it can cause current-measurement inaccuracies of as much as 25% at transmit currents of 2 amps or higher. Alert #17 also mentioned increasing the value of C42 to 0.1 uF. This change is still required on older K2s. Revision B K2s already have the correct value of C42. MODIFICATION INSTRUCTIONS If your K2 is revision B (s/n 3000-3077 only): - Remove C44 on the Control board. NOTE: This is specified on the errata sheet for revision B K2s starting with serial number 3078. If your K2 is revision A or XC: - If you added C44 previously (alert #17), REMOVE IT. - If you did not increase C42 (alert #17), do so now. Use an 0.1 uF or larger ceramic or monolithic capacitor (not electrolytic). If you don't have any suitable capacitors, send a request to parts at elecraft.com and we'll send you an 0.1-uF cap at no charge. NOTE: If you built a KPA100, you have already made the change to C42. ++++++++++++++++ Date: Mon, 02 Dec 2002 16:33:59 -0800 From: Wayne Burdick Organization: Elecraft To: Elecraft Subject: [Elecraft] Builder Alert #19: part # for needed capacitor If you need an 0.1-uF capacitor to implement alert #19 (C42 on the Control board), please request Elecraft p/n E530011. Chances are you can use any 0.1 to 0.5 uF capacitor you have in your junk box. It must be a disc, monolithic, or other non-electrolytic type. 73, Wayne N6KR +++++++++++++++ From: "Don Brown" To: "David Schornak" , "Elecraft" , Subject: Re: [Elecraft] ssb argh Date: Thu, 5 Dec 2002 09:59:53 -0600 Hi If you are building a B model (>3000 S/N) then there is not a pot for r60, it is a 100 ohm fixed resistor. The manual method of setting R1 is good but I do it a little differently. I use my OHR wattmeter set on the 100 mW scale and adjust R1 for minimum output while holding the PPT button and no sound into the microphone. Don Brown ++++++++++++++++ From: "Rich Lentz" To: "'Dean Maples'" , "'Bob - AG5Q'" , Subject: RE: [Elecraft] K2 Front Panel Board - Resistance Measurements ?? Date: Wed, 1 Jan 2003 20:47:00 -0600 Looking at the schematics for K2(A) and K2(B) and the resistance checks on page 27 for both versions you will note that both indicate J1 pin 3 is ground (0 ohms). This is correct for those models less than 3000, however, those above 3000 have the mod that got rid of the scratchy audio, and thus there is no ground and should read the same as the other pins of R3 (AF POT). Rich, KE0X ++++++++++++++++ From: "Gregg Lengling" To: , Subject: RE: [Elecraft] K2 s/n 3021 Display Board: Date: Thu, 2 Jan 2003 11:04:51 -0600 Did you read the errata sheet included with your radio...this was changed on S#'s above 3000. You have the right reading....continue with the building. Gregg R. Lengling, W9DHI Camel Communications, Inc. http://www.camelcomm.com Politics is the art of appearing candid and completely open, while concealing as much as possible. -States: The Bene Gesserit View -----Original Message----- From: elecraft-admin at mailman.qth.net [mailto:elecraft-admin at mailman.qth.net] On Behalf Of Martin AC6RM Sent: Thursday, January 02, 2003 10:50 AM To: elecraft at mailman.qth.net Subject: [Elecraft] K2 s/n 3021 Display Board: Hello; I am part-way through assembling K2 s/n 3021. The resistance checks detailed on page 27 of the manual all checked out okay except for J1 pin 3. This is supposed to be ground, but I get a high impedance (>1M). I continued on with construction despite the failure and all tests shown on pages 41 through 46 passed. Any ideas? Seems a ground connection would be a trace issue (or maybe a diode issue -- I double-checked the polarity on all my diodes). There is conductivity through the connector itself, just not to ground. What did I do wrong? Thanks ES 73, Martin +++++++++++++++++ From: "Stephan Walder, HB9DDO - K2" To: "'Elecraft'" Subject: Re: [Elecraft] K2 #3021 -- Press On or Not: Date: Sun, 5 Jan 2003 11:39:21 +0100 Hi Martin just a little comment on the "missing" caps - I thought I had the same = problem but after mailing with Elecraft I found them: the 47pF and 56pF are 5% values, that is they are among the blue, small = ones with 470J and 560J written on them... I looked among the brown ones in the first place too ;-) 73, Stephan, HB9DDO, S/N 3128 P.S. I just finished assembly and test, part 2 without any big problem = up till now - spent a lot of time since the package arrived just before = xmas :-) -- org -- Betreff: [Elecraft] K2 #3021 -- Press On or Not: Howdy; I'm at the point in the assembly manual where I'm about to begin "Alignment and Test Part II." A good chunk of the RF board is complete. There are a few caps missing from the kit, though (all 4 of the 47pf and all 4 of the 56pf). While I hunt those up and wait for them to come in (or for Abletronics to open on Monday), can I plow on ahead with the installation of the rest of the components? My girlfriend says I should wait. My daughter's retort is always "Patience is Waiting Without Complaining." I'm kinda anxious to press on while the iron's hot. 73, Martin ++++++++++++++++ From: "Dave" To: "n3drk" Cc: Subject: Re: [Elecraft] confused with all mods k2 Date: Sun, 5 Jan 2003 11:13:04 -0000 John Like yourself, I don't want to deviate too far from the "Elecraft standard K2". However, there are some mods that are well worth the effort. In no particular order these are: Changing the capacitors in the higher band filters - reduces the image interference from the 15 MHz broadcast band when listening on 24.9 MHz, less of an issue at the moment as we move away from sunspot max. The "scratchy volume control" modification, makes a huge difference if yours sounds scratchy. Only necessary if your volume control becomes irritating. The "2nd filter mod" makes the SSB receive signal sound significantly better. All these mods are covered in the "A to B" kit. Most take a matter of minutes to do, although the volume control modification takes around an hour. There are pictures of the "before and after" results of the 2nd filter mod on my web pages at http://www.astromag.co.uk/k2/ 73's Dave, G4AON K2 #1892 ----- Original Message ----- From: "n3drk" To: "elecraft" Sent: Sunday, January 05, 2003 9:33 AM Subject: [Elecraft] confused with all mods k2 > With all the modifications for the k2 that are out there i just dont know > where to start. I am trying to keep this rig as close to the original design > as possible so i dont want to put every mod into it. > > I have k2 s/n 2444 and purchased the kat2 at the same time. Last week i > purchased and received the ksb2 ssb module and have yet to build it. > > My manual states it is REV C. I am becoming somewhat confused with all the > mods for below s/n 3000 and rev a to b etc. > > With my equipment what do i need to install (basics) to get it up to par? > > Thanks in advance > > john ++++++++++++++ Date: Sun, 5 Jan 2003 05:34:30 -0800 (PST) Subject: Re: [Elecraft] K2 #3021 -- Press On or Not: From: "Martin AC6RM" To: Cc: Reply-To: elecraft at ac6rm.net Thanks Stephan (and Gil, who also pointed this out) -- I have these caps! I shall press on! 73, Martin +++++++++++++++ From: "Don Brown" To: "Wallace, Andy" , "'Elecraft'" Subject: Re: [Elecraft] Serial 3000+ K2: AGC threshold setting Date: Wed, 22 Jan 2003 11:45:13 -0600 Hi I am currently building two K2's. I just checked the setting of R1 on the control boards after calibration and both pots are at about 1/2 of the rotation. I had no problems making this adjustment. Are you sure RP6 is 5.1K and R1 is a 50K pot. That's about all that can be wrong unless it's a bad connection somewhere. Don Brown KD5NDB ----- Original Message ----- From: "Wallace, Andy" To: "'Elecraft'" Sent: Wednesday, January 22, 2003 11:30 AM Subject: [Elecraft] Serial 3000+ K2: AGC threshold setting > Hi, Folks. Quick question to the K2 3000+ owners: > Did you have trouble setting the AGC threshold? This > was done with R1 on the Control Board, measuring at > U2 pin 5. Manual recommends 3.9V. I could only get > mine to 3.8V and that was with R1 fully counter-clockwise > as viewed facing the pot. Did so with RF gain fully > clockwise. 8A regulated line is 7.99V on my meter. > Leaving it at 3.8, I was able to do the S meter calibration > for zero and full-scale ok. > > Circuit is pretty simple -- RP6 is pretty much it! -- so > I am wondering what is up. I checked my work and all seems > OK, but will scrutinize more when I can get back to it. > > Andy +++++++++++++++++ From: "Donnie Garrett" To: Cc: Date: Wed, 22 Jan 2003 17:17:20 -0500 Subject: [Elecraft] Elecraft] Serial 3000+ K2: AGC threshold setting Andy: I'm also building a K2 SN# 3186. I just finished the testing found on = page 46 in the K2 manual. I also ran into the exact same problem! I = could only get the AGC threshold to 3.8V before running out of = adjustment on R1. Keep me posted as to what you find out. I would = certainly like to know. Everything else checked just fine. Im ready = for Assembly, Part II page 47 = Donnie Garrett / WA9TGT ----- Original Message ----- From: "Wallace, Andy" To: "'Elecraft'" Sent: Wednesday, January 22, 2003 11:30 AM Subject: [Elecraft] Serial 3000+ K2: AGC threshold setting > Hi, Folks. Quick question to the K2 3000+ owners: > Did you have trouble setting the AGC threshold? This > was done with R1 on the Control Board, measuring at > U2 pin 5. Manual recommends 3.9V. I could only get > mine to 3.8V and that was with R1 fully counter-clockwise > as viewed facing the pot. Did so with RF gain fully > clockwise. 8A regulated line is 7.99V on my meter. > Leaving it at 3.8, I was able to do the S meter calibration > for zero and full-scale ok. > > Circuit is pretty simple -- RP6 is pretty much it! -- so > I am wondering what is up. I checked my work and all seems > OK, but will scrutinize more when I can get back to it. > > Andy ++++++++++++++++++ Date: Wed, 22 Jan 2003 19:27:45 -0800 (PST) Subject: Re: [Elecraft] Bfo range low From: "Martin AC6RM" To: Cc: Reply-To: elecraft at ac6rm.net Contact support at elecraft.com; they've found that the last batch of matched crystal sets weren't quite as wide as their original design sets. A cap on the bottom of the board solves the problem, but contact Gary at support before you do this to get precise instructions. I did this and he helped me solve it. I thought that they were going to post something on the web page -- a builder alert or something -- but I don't see it up there. 73 ES GL, Martin AC6RM (k2#3021, "Its Shake'n'Bake and ah healped!") > My BFO test came out low. The best range I can get is 3.55Khz. I used a > outboard freq counter to set 4 mhz osc. but it is still 3.55khz. Any > suggestions > +++++++++++++++++++ From: "Don Brown" To: "Dwight K9ERF" , "Wallace, Andy" , "'Elecraft'" Subject: Re: [Elecraft] Serial 3000+ K2: AGC threshold setting Date: Wed, 22 Jan 2003 22:23:55 -0600 Hi This problem may be the wrong value pot. It should be 50K. I have two control boards that work properly and the resistance measured across the pot is about 9.5K with the proper calibration. The pot is at the half way point on the adjustment range. Try measuring across your pot and if you get about 9K at full clockwise if so, then the pot is the wrong value. Don Brown KD5NDB ----- Original Message ----- From: "Dwight K9ERF" To: "Wallace, Andy" ; "'Elecraft'" Sent: Wednesday, January 22, 2003 5:25 PM Subject: Re: [Elecraft] Serial 3000+ K2: AGC threshold setting > Same problem with #3183, I was able to get 3.6vdc with a fluke meter. > ++++++++++++++++++ From: "Don Brown" To: "Elecraft" Date: Thu, 23 Jan 2003 08:54:51 -0600 Subject: [Elecraft] AGC treshold adjustment Hi This is an email I sent to Andy Wallace. I thought the list may be interested also as there have several other builders with this problem Don Hi If your pot was marked 50K then that is not the problem. I was guessing maybe the wrong pot was in your kit. There are 5K pots used in other Elecraft products that look just like the 50K pot so I thought it could be mixed up. Looking at the circuit there are only 4 things I can see that would make the voltage adjust range low. 1) the wrong value pot 2) the wrong value or type RP6 3) the wrong voltage on the +8 supply 4) U2B loading down the circuit at pin 5. The circuit is a simple resistance divider. If the RF gain pot is at maximum then pin 6 of rp6 is grounded. Doing the math I get a maximum of 3.8 volts if the supply voltage is 8.0 volts just what you are getting. I went out and measured the circuit on my two control boards and I am getting 8.5 volts out of the regulator. This is why I can adjust R1 above 3.8 volts. The tolerance on the regulator may be the problem if your 8 volt supply is on the low side then you will not be able to get 3.9 volts on the R1 adjustment. The simplest fix for this is to tack a resistor around 51K across pins 3 and 4 of RP6. This will raise the adjustment range and make up for the lower 8 volt supply. Don Brown KD5NDB ----- Original Message ----- From: "Wallace, Andy" To: "'Don Brown'" Cc: "Wallace, Andy" Sent: Thursday, January 23, 2003 7:03 AM Subject: RE: [Elecraft] Serial 3000+ K2: AGC threshold setting > Thanks, Don -- will check that. Two other people emailed me (possibly > cc'ed to the List) saying they had the exact same problem. > > What was the value of the wrong-value pot? > > When you say across the pot, you mean from wiper to one end, since > it's about halfway? Then you say 9K full clockwise. I'm confused. > I'd expect more like 25K in the middle. > > I may just pull it and check end to end! > > One thing I did not mention was that over the weekend, after I had > found I could only get to 3.8, I did continue with construction. (My > risk!) Well the RF board is complete to the point where the 40m rx > is alive. HOWEVER: now that it is, it seems insensitive. With the filters > properly adjusted (AC6RM's recent forwarded method works great!) the > sensitivity with the preamp ON is about the same as my K1. I'd expect > better. All other alignment went fine, and the 40m coils peaked fine. > But I'd expect better. With the preamp off, I can barely hear 40m > local hash. With preamp on, audio has to be at about ten o'clock, > and SWBC stations I'd expect to be at 40 over are more like S-9. > For what it's worth, my CAL S LO is 183 and my CAL S HI is 019. > Does that match one of yours at all? My feeling is the AGC is holding > signals down. > > Thanks very much for the post -- I checked my workmanship several times > and have been scratching my head on this one. If I remember right, > the pot WAS marked 50K, too. > > Andy +++++++++++++++++ Date: Sun, 26 Jan 2003 11:53:24 -0500 From: "David A. Belsley" To: Donnie Garrett , Elecraft at mailman.qth.net Subject: Re: [Elecraft] Xtal Filter Crystals Donnie: You're fine. Go ahead. best wishes, dave belsley, w1euy --On Sunday, January 26, 2003 10:56 AM -0500 Donnie Garrett wrote: > I am currently building a K2 SN# 3186. On page (50) of the construction > manual it states next install the 4.9152 MHz crystals X5 thru X11 All > (7) crystals in my Filter xtal set envelope are of a different frequency. > They are marked 4.9136 Mhz What gives? Any suggestions before I proceed > forward with construction? > > > Donnie Garrett / WA9TGT ++++++++++++++++ From: "Roy Vickers" To: Subject: RE: [Elecraft] #3062 Part II BFO test problem Date: Mon, 27 Jan 2003 09:08:13 -0600 *** That happened to me also and Gary at Elecraft responded with: *** We know the last batch of BFO crystals have higher Lm or motional inductance, and do not move as far. I tested over 200 of them last month and found that to be the case. The current recommendation is to add 47pF to C174, and 120pF to C173 on the bottom of the PCB if the BFO range is too small. Tests I did for Wayne shows this usually solves the problem. As long as you can reach 4913.0 at the low end, and 4916.5 at the high end - you should be fine. Wayne posted some info about this on the Elecraft reflector last month. Be sure and ground the cans of the crystals before concluding what the range is, since it can make a 200-300 Hz difference at the lower freq. It does not change the higher freq. as much, maybe 20-50Hz. > If your BFO range is too small, then add the caps. If you do not have them, email parts at elecraft.com and Scott will send you two caps as mentioned above. If you wish, we can send a new set of the BFO crystals with a wider range and/or lower freq. But adding the caps, or just changing C173, C174 to larger single cap values of 330pF for C173 and 120pF for C174 would be easier in my opinion. Wayne came up with this change for the kits with slightly low BFO range, and I verified it works well. C173: 220 + 120 = 340, round down to 330 pF. C174: 82 + 47 = 129, round down to 120 pF All of us are aware of the narrower range of the last batch of BFO crystals. One good thing about them, is that they should have less drift with temperature changes. Some of the previous batches had so much range (5-6kHz, and too much in fact), that they could increase the drift of the BFO. You can also connect a 3.3pF to 4.7pF across the PCB pad of X3 or X4 that connects to L33, and to ground. Use the either of the pair of ground pads near the crystals that is used to ground the crystal can. This alone can make a 1-2kHz drop in the low BFO frequency without affecting the BFO high frequency. *** I had Elecraft send me new xtals but that didn't fix. As of this writing, I put my old 39mh L33 back in, which is not a option if you have sn3000+. I'm still conversing with Gary on this issue and several others are experiencing the same problem. -----Original Message----- From: elecraft-admin at mailman.qth.net [mailto:elecraft-admin at mailman.qth.net]On Behalf Of Ron Schuster Sent: Monday, January 27, 2003 8:46 AM To: elecraft at mailman.qth.net Subject: [Elecraft] #3062 Part II BFO test problem My frequency measurement results are: high freq is 4917.0, low freq is 4913.5 The low frequency spec is less than 4912. The range spec is 3.6. It fails both of these. I have checked all components and soldering. Verified X3, X4, D37, D38, L33, C169, C173, C174 Any ideas?? <>-< <>-< <>-< <>-< <>-<<>-<<>-<<>-<<><-< Ron Schuster (N9RC) Cincinnati, OH rschuste at one.net +++++++++++++++++ Date: Sat, 01 Feb 2003 10:22:23 -0600 To: "Donnie Garrett" , From: Tom Hammond Subject: Re: [Elecraft] Mounting BFO Toroid L33 Donnie: >Im currently building a K2 SN# 3000+. What keep the leads of the 5.1 Meg >Ohm resistor used to hold L33, the BFO toroid from coming in electrical >contact with the windings of the coil? It would appear that the resistor >leads will actually position them self's down between the actual coil >windings when snug enough to hold the toroid coil. Is this ok? The enamel insulation coating the wire of the L33 is pretty tough. Secondly, the only real concern might be the leads of the 5M resistor shorting out two ADJACENT toriodal inductor turns (and this would be very remote) due to the enamel of BOTH adjacent leads having broken down. The fact that a 5M resistor was used pretty much means that it will have no electrical effect upon the toroidal inductor even if it did happen to short to single turns on either side of the inductor. 73, Tom Hammond N0SS ++++++++++++++++++ Date: Fri, 28 Feb 2003 09:00:20 -0800 From: Eric Swartz WA6HHQ - Elecraft Organization: Elecraft To: elecraft at ac6rm.net Cc: Elecraft at mailman.qth.net Subject: Re: [Elecraft] KPA100 -- RS232 Interface Prep: Correct - The control board mod is NOT required for Rev B K2 PCBs (sn 3000+) when you add the KPA100 or KIO2. 73, Eric WA6HHQ Elecraft ============== Martin AC6RM wrote: > Need confirmation that the "Control Board Preparation" steps on page 51 of > the KPA100 manual are NOT required for "Rev. B" "CONTROL" boards. I show > a short between pin 25 of U6 and Pin 1 of P4, as well as Q5-gate and U8 > pin 4 already. And I can't find a trace between U6 pin 25 and the gate of > Q5. I just don't have anything in writing that says "don't do these." ++++++++++++++++++ From: bills4570 at att.net To: elecraft at mailman.qth.net Date: Sat, 01 Mar 2003 18:18:11 +0000 Subject: [Elecraft] Solved: Sick K2 following A to B mod Hi there, I'm almost embarassed to take up the list's time with this, but I suffered over it, and if it saves someone else some time, I think it's worth it: A couple months ago, I performed the A to B mod on K2 serial number 2715. When I finished, I found that I had intermittant audio performance due to an incomplete trace cut. I stepped back through my steps on the audio pot mod and found and corrected the problem. After that, I was never completely sold on the receive performance, but I had changed antennas during the A to B mod, and I attributed the poor receive performance to the compromise antenna (aren't they all!), and to a downturn in the band conditions. One Saturday morning, I was scratching for a PSK-31 QSO, and found that others could hear me fine, but that I couldn't copy them! Now that was a switch for a low power addict like myself! One chap, who I could not hear, was kind enough to send me a signal report by e-mail. I dragged another transceiver out of storage and started doing some receive performace comparisons. I found that the K2 receiver was practically dead. On PSK, the waterfall was filled with signals using the Brand X tranceiver, but the K2 showed only the 3 strongest ones. Hmmmmmmm...... I spent the day tearing the K2 apart and checked each and every step of the A to B mod. I re-flowed each and every solder joint that would have anything to do with receive sensitivity. There was no improvement. The K2 sat there on my bench with a taunting smirk on it's front panel for a few more days, while I broke the arms off my Wayne and Eric voodoo dolls. Yesterday, I took the top off to do some signal tracing. #2715 is equipped with the internal ATU, which is removed with the top. I began wondering how the RF signal could be introduced without the antenna connections in the top cover. I decided to try the original connector, which was capped off....... no luck. On a whim, I connected the antenna to the receive only connector, which came with the 160 M kit. Wow, the receiver spang to life! You know the rest of the story........ Sheeeeesh! I had never checked the menu selections for the receive antenna, and the K2 was set up with the receive antenna "on". That meant that the receive path through the Ant 1 and Ant 2 connections was disconnected except on transmit. A quick re-configuration of this feature brought the K2 back to it's hot receiving self. The "Rant OFF" selection must be done for each band unless you WANT to use a seperate receive antenna (like on 160, for instance). It had been a major case of "OPERATOR ERROR" the whole time. I had become used to the features I used most often, but forgot about the many other useful features which make the K2 such a great rig! Hope this post helps someone to avoid this problem. -- Bill Schwantes, W7QQ ++++++++++++++++++++ From: "Don Brown" To: "n5gf" , Subject: Re: [Elecraft] Construction Question Date: Sat, 15 Mar 2003 08:26:47 -0600 Hi It is best to build the K2 and get everything working before installing any options. You can install all of the connectors on the RF board for the options while building the basic K2 but leave the jumpers in place until the basic radio is complete. Then add the options one at a time. Note your K2 is above 3000 so the spur and ALC mod are already on the board so ignore the mod kit that comes with the KPA100. For those with serial numbers below 3000 the spur and ALC mod for the KPA100 can be added to the basic K2 at the time of the basic assembly. If you add the mod later you will need to touch up the alignment again. Don Brown ----- Original Message ----- From: "n5gf" To: Sent: Saturday, March 15, 2003 8:01 AM Subject: [Elecraft] Construction Question I ordered my K2 with all the options except the 160 Meter module. I am in the midst of construction, nearly through with the RF board and notice that there are some component changes required for installing the 100 Watt PA. There may be other changes necessary for the other options. I haven't looked yet. The question is: Is it better to build the base K2 test it all out and then make the mods for adding the other options or should I just go ahead and include these changes in the original build? How will all this affect the test and check-out of the unit when the RF board is completed and before the options are plugged in? tnx es 73 de N5GF Ed K2 #3332 ++++++++++++++++