K2 BFO Test Problems
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Hello to the group.
I am currently working through the Alignment and Test, Part II and have run into the following issue. When I perform the BFO Test, I don't get the proper range. The set of values I get are: BFO High Freq.: 4917.31 kHz BFO Low Freq.: 4916.97 kHz Range: 0.34 kHz The documentation states that if the BFO range is less than 3.6 kHz, the varactor diodes (D37 and D38) or the crystals (X3 and X4) may be incorrect. However, I've verified them and they are correct. I've also gone around looking for bad soldering (cold joints or bridges) and didn't see anything obvious. I've checked the resistors and capacitors in the BFO section and they appear to be correct. Does anyone have any ideas of where I should look next? 73, Craig AC6NN _______________________________________________ Elecraft mailing list Post to: [hidden email] You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com |
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Hello again,
I've continued my troubleshooting efforts but the problem persists. I had reflowed all connections except those of X3, so I removed L33 and R116 to do so. Everything appears to be well connected and I don't see any shorts. I checked the DC voltages on U11 using the internal probe and have the following values: Pin 1: 1.4 Pin 2: 1.4 Pin 3: 0.0 Pin 4: 4.8 Pin 5: 4.8 Pin 6: 5.6 Pin 7: 5.0 Pin 8: 6.0 I used the RF probe to check the voltages with the following results: U11, pin 6: 0.74 TP2: 0.024 The DC voltages for U11 pins 6 and 7 are a bit low and the RF probe values are on the edges. Is it possible that U11 is bad? 73, Craig On 18 Feb, 2007, at 10:46, Craig Young wrote: > Hello to the group. > > I am currently working through the Alignment and Test, Part II and > have run into the following issue. When I perform the BFO Test, I > don't get the proper range. The set of values I get are: > > BFO High Freq.: 4917.31 kHz > BFO Low Freq.: 4916.97 kHz > Range: 0.34 kHz > > The documentation states that if the BFO range is less than 3.6 > kHz, the varactor diodes (D37 and D38) or the crystals (X3 and X4) > may be incorrect. However, I've verified them and they are > correct. I've also gone around looking for bad soldering (cold > joints or bridges) and didn't see anything obvious. I've checked > the resistors and capacitors in the BFO section and they appear to > be correct. > > Does anyone have any ideas of where I should look next? > > 73, > > Craig AC6NN > > _______________________________________________ > Elecraft mailing list > Post to: [hidden email] > You must be a subscriber to post to the list. > Subscriber Info (Addr. Change, sub, unsub etc.): > http://mailman.qth.net/mailman/listinfo/elecraft > Help: http://mailman.qth.net/subscribers.htm > Elecraft web page: http://www.elecraft.com _______________________________________________ Elecraft mailing list Post to: [hidden email] You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com |
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Craig,
The problem is most likely in one of the following areas: 1) The L33 inductor 2) The varactors 3) The crystals themselves. The very most likely problem is a poor solder connection, and the second most likely is misplaced components. The DC voltages look to be within reason, and it is probably not the fault of U11. We can get to precise measuremnts tomorrow, it is getting late here today. 73, Don W3FPR > -----Original Message----- > > Hello again, > > I've continued my troubleshooting efforts but the problem persists. > I had reflowed all connections except those of X3, so I removed L33 > and R116 to do so. Everything appears to be well connected and I > don't see any shorts. > > I checked the DC voltages on U11 using the internal probe and have > the following values: > > Pin 1: 1.4 > Pin 2: 1.4 > Pin 3: 0.0 > Pin 4: 4.8 > Pin 5: 4.8 > Pin 6: 5.6 > Pin 7: 5.0 > Pin 8: 6.0 > > I used the RF probe to check the voltages with the following results: > > U11, pin 6: 0.74 > TP2: 0.024 > > The DC voltages for U11 pins 6 and 7 are a bit low and the RF probe > values are on the edges. Is it possible that U11 is bad? > > 73, > > Craig > > > On 18 Feb, 2007, at 10:46, Craig Young wrote: > > > Hello to the group. > > > > I am currently working through the Alignment and Test, Part II and > > have run into the following issue. When I perform the BFO Test, I > > don't get the proper range. The set of values I get are: > > > > BFO High Freq.: 4917.31 kHz > > BFO Low Freq.: 4916.97 kHz > > Range: 0.34 kHz > > > > The documentation states that if the BFO range is less than 3.6 > > kHz, the varactor diodes (D37 and D38) or the crystals (X3 and X4) > > may be incorrect. However, I've verified them and they are > > correct. I've also gone around looking for bad soldering (cold > > joints or bridges) and didn't see anything obvious. I've checked > > the resistors and capacitors in the BFO section and they appear to > > be correct. > > > > Does anyone have any ideas of where I should look next? > > > > 73, > > > > Craig AC6NN > > > > _______________________________________________ > > Elecraft mailing list > > Post to: [hidden email] > > You must be a subscriber to post to the list. > > Subscriber Info (Addr. Change, sub, unsub etc.): > > http://mailman.qth.net/mailman/listinfo/elecraft > > Help: http://mailman.qth.net/subscribers.htm > > Elecraft web page: http://www.elecraft.com > > _______________________________________________ > Elecraft mailing list > Post to: [hidden email] > You must be a subscriber to post to the list. > Subscriber Info (Addr. Change, sub, unsub etc.): > http://mailman.qth.net/mailman/listinfo/elecraft > > Help: http://mailman.qth.net/subscribers.htm > Elecraft web page: http://www.elecraft.com > -- > No virus found in this incoming message. > Checked by AVG Free Edition. > Version: 7.5.441 / Virus Database: 268.18.1/691 - Release Date: > 2/17/2007 5:06 PM > No virus found in this outgoing message. Checked by AVG Free Edition. Version: 7.5.441 / Virus Database: 268.18.1/691 - Release Date: 2/17/2007 5:06 PM _______________________________________________ Elecraft mailing list Post to: [hidden email] You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com |
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All,
I thought I'd write describing what the issue was for the record. In the end it was a bad connection on U10 of the Control Board. Pin 13 was not soldered correctly, so V BFO was incorrect. When tested on the RF board V BFO did not move between 0 and 8 Vdc as required (it hovered around 5.5 Vdc). I much appreciate the effort of Gary AB7MY at Elecraft for helping me track this down. 73, Craig AC6NN On 19 Feb, 2007, at 0:17, Don Wilhelm wrote: > Craig, > > The problem is most likely in one of the following areas: > 1) The L33 inductor > 2) The varactors > 3) The crystals themselves. > > The very most likely problem is a poor solder connection, and the > second > most likely is misplaced components. > The DC voltages look to be within reason, and it is probably not > the fault > of U11. > > We can get to precise measuremnts tomorrow, it is getting late here > today. > > 73, > Don W3FPR > >> -----Original Message----- >> >> Hello again, >> >> I've continued my troubleshooting efforts but the problem persists. >> I had reflowed all connections except those of X3, so I removed L33 >> and R116 to do so. Everything appears to be well connected and I >> don't see any shorts. >> >> I checked the DC voltages on U11 using the internal probe and have >> the following values: >> >> Pin 1: 1.4 >> Pin 2: 1.4 >> Pin 3: 0.0 >> Pin 4: 4.8 >> Pin 5: 4.8 >> Pin 6: 5.6 >> Pin 7: 5.0 >> Pin 8: 6.0 >> >> I used the RF probe to check the voltages with the following results: >> >> U11, pin 6: 0.74 >> TP2: 0.024 >> >> The DC voltages for U11 pins 6 and 7 are a bit low and the RF probe >> values are on the edges. Is it possible that U11 is bad? >> >> 73, >> >> Craig >> >> >> On 18 Feb, 2007, at 10:46, Craig Young wrote: >> >>> Hello to the group. >>> >>> I am currently working through the Alignment and Test, Part II and >>> have run into the following issue. When I perform the BFO Test, I >>> don't get the proper range. The set of values I get are: >>> >>> BFO High Freq.: 4917.31 kHz >>> BFO Low Freq.: 4916.97 kHz >>> Range: 0.34 kHz >>> >>> The documentation states that if the BFO range is less than 3.6 >>> kHz, the varactor diodes (D37 and D38) or the crystals (X3 and X4) >>> may be incorrect. However, I've verified them and they are >>> correct. I've also gone around looking for bad soldering (cold >>> joints or bridges) and didn't see anything obvious. I've checked >>> the resistors and capacitors in the BFO section and they appear to >>> be correct. >>> >>> Does anyone have any ideas of where I should look next? >>> >>> 73, >>> >>> Craig AC6NN >>> >>> _______________________________________________ >>> Elecraft mailing list >>> Post to: [hidden email] >>> You must be a subscriber to post to the list. >>> Subscriber Info (Addr. Change, sub, unsub etc.): >>> http://mailman.qth.net/mailman/listinfo/elecraft >>> Help: http://mailman.qth.net/subscribers.htm >>> Elecraft web page: http://www.elecraft.com >> >> _______________________________________________ >> Elecraft mailing list >> Post to: [hidden email] >> You must be a subscriber to post to the list. >> Subscriber Info (Addr. Change, sub, unsub etc.): >> http://mailman.qth.net/mailman/listinfo/elecraft >> >> Help: http://mailman.qth.net/subscribers.htm >> Elecraft web page: http://www.elecraft.com >> -- >> No virus found in this incoming message. >> Checked by AVG Free Edition. >> Version: 7.5.441 / Virus Database: 268.18.1/691 - Release Date: >> 2/17/2007 5:06 PM >> > -- > No virus found in this outgoing message. > Checked by AVG Free Edition. > Version: 7.5.441 / Virus Database: 268.18.1/691 - Release Date: > 2/17/2007 > 5:06 PM > _______________________________________________ Elecraft mailing list Post to: [hidden email] You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com |
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