K2 FINISHED
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After weeding thru a few problems my K2 is up and running good. So far I have not added any extra modules and the basic K2 is doing fine with on the air QSOs. I will share my problems to maybe help some one keep from making same mistakes. Don W3FPR was VERY helpful guiding me thru my problems. I put C6 RF board in the wrong place. The book says 2 outside terminals so I put it in the 2 closest to the outside of the case.. WRONG. Then I lost the BFO because the 5 meg resistor across the coil was shorting it out. Guess I pushed too hard on the tape I put over it. I also installed T4 backwards which gave too much current drawn on Tx. Now I'm building my extra modules and taking a break to have some fun on the air with the K2. Great kit...fun to build...and good rig when done. 73 Rich WB4VFN
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Hello,
I'm in the middle of building a K2, S/N 6412. I have a couple of questions, hopefully some of the knowledgeable Elecraft people on this forum can help. While doing the Alignment and test Part 1, I had a couple of readings that were not in specs. 1. Page 48, Setting the AGC Threshold, the manuals calls for adjusting R-1 for a reading of 3.80VDC on pin 5 of U2. The highest R1 would adjust to is 3.60VDC. 2. Page 48 Bargraph Current test. The manual calls for a current reading of 0.16 to 0.18. My K2 reads 0.25 amps. That is quite a bit higher than what is called for. Any suggestions? Are these readings anything to worry about? Thank you in advance for any help. Best, DW Holtman WB7SSN _______________________________________________ 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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DW,
Check the 8 volt regulator output (ControlBoard U4 upper leg). If that is less than 7.6 volts, you may want to replace the regulator. It may help with both problems. BUT if your 8 volt regulator output is OK, then you should look for the component(s) that have the wrong value. 73, Don W3FPR DW Holtman wrote: > Hello, > > I'm in the middle of building a K2, S/N 6412. > > I have a couple of questions, hopefully some of the knowledgeable > Elecraft people on this forum can help. > > While doing the Alignment and test Part 1, I had a couple of readings > that were not in specs. > > 1. Page 48, Setting the AGC Threshold, the manuals calls for > adjusting R-1 for a reading of 3.80VDC on pin 5 of U2. The highest R1 > would adjust to is 3.60VDC. > > 2. Page 48 Bargraph Current test. The manual calls for a current > reading of 0.16 to 0.18. My K2 reads 0.25 amps. That is quite a bit > higher than what is called for. > > Any suggestions? Are these readings anything to worry about? > 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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DW:
The exact thing happened to me. Elecraft tech support suggested measuring the output of the 8-volt regulator. Mine was 7.56 volts. Replaced it, even though that isn't considered "bad" by the mfr's specs, and then I could easily set mine to 3.80 volts. Interestingly, the replacement regulator gives 8.2 volts. Also make sure that your RF gain control is set per the test requirement (I think it wanted full clockwise). Try turning that knob from full CW to full CCW and make sure that you can see the AGC voltage varying. That's a quick check for your wiring to the pot. Most likely, your 8v regulator is being too miserly. 73, Dave K7DAA http://www.k7daa.com On Feb 20, 2008, at 6:39 AM, Don Wilhelm wrote: > DW, > > Check the 8 volt regulator output (ControlBoard U4 upper leg). If > that is less than 7.6 volts, you may want to replace the regulator. > It may help with both problems. BUT if your 8 volt regulator output > is OK, then you should look for the component(s) that have the wrong > value. > > 73, > Don W3FPR > > DW Holtman wrote: >> Hello, >> >> I'm in the middle of building a K2, S/N 6412. >> >> I have a couple of questions, hopefully some of the knowledgeable >> Elecraft people on this forum can help. >> >> While doing the Alignment and test Part 1, I had a couple of >> readings that were not in specs. >> >> 1. Page 48, Setting the AGC Threshold, the manuals calls for >> adjusting R-1 for a reading of 3.80VDC on pin 5 of U2. The highest >> R1 would adjust to is 3.60VDC. >> >> 2. Page 48 Bargraph Current test. The manual calls for a current >> reading of 0.16 to 0.18. My K2 reads 0.25 amps. That is quite a bit >> higher than what is called for. >> >> Any suggestions? Are these readings anything to worry about? >> > _______________________________________________ > 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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In reply to this post by DW Holtman
Hello,
I want to thank all of the help I received on this problem. The AGC adjustment problem was solved by replacing the 8.0VDC regulator with one that puts out 8.0 volts not 7.5 VDC.. I also had a problem where the MCU on the control board sometimes would not start, it just froze and all controls were inop. I found an un-soldered (surprise surprise) connection. Not I have a new problem, and was wondering if anyone has any ideas. As I started the alignment and test Part II. everything went fine until I got to the 4th step on the left column on page 64. There is no output on the left hand side of R-30. I traced this back to U5 (I think) The voltage does not vary on pin 7 of U5 as the frequency is varied. It stays at VCC, 5 VDC. I think this changing DC voltage must be there to make U4 and U6B operate to get the voltage on R-30. Am I wrong on this, very little to no experience working on PLL Synthesizers. All of the other voltages on U5 look good. Any suggestions on where to go from here. The PLL reference oscillator is working, clean signal at around 12.096 MHZ. It might be a soldering problem, but I really do not think so, I have spent a lot of time looking closely at solder joints. I will keep checking and re-heating the solder joints. Any suggestions on what to check would help. Best, DW Holtman WB7SSN ----- Original Message ----- From: "DW Holtman" <[hidden email]> To: <[hidden email]> Sent: Wednesday, February 20, 2008 7:25 AM Subject: [Elecraft] K2 Assembly Question > Hello, > > I'm in the middle of building a K2, S/N 6412. > > I have a couple of questions, hopefully some of the knowledgeable Elecraft > people on this forum can help. > > While doing the Alignment and test Part 1, I had a couple of readings that > were not in specs. > > 1. Page 48, Setting the AGC Threshold, the manuals calls for adjusting > R-1 for a reading of 3.80VDC on pin 5 of U2. The highest R1 would adjust > to is 3.60VDC. > > 2. Page 48 Bargraph Current test. The manual calls for a current reading > of 0.16 to 0.18. My K2 reads 0.25 amps. That is quite a bit higher than > what is called for. > > Any suggestions? Are these readings anything to worry about? > > Thank you in advance for any help. > > Best, > DW Holtman > WB7SSN > > _______________________________________________ > 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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