[Elecraft] U1 Problem on #3706

[John Smith]

Just a note to anyone that might experience the problem that I have with =
my new K2.  I'm calling it my K0 for now until I get the replacement =
part and actually get it running ;)

Once all was put together, I had a dead receiver on 15 and 17 meters.  =
After many hours of signal tracing and head scratching, I found that =
when 17 meters was selected, relay K7 is also closed at the same time =
causing the 10/12 meter bandpass filter circuit to be active at the same =
time.  Initially, I thought that K5 might be bad.  To make a long story =
shorter, I eventually found that Pin 22 of U1 is shorted internally =
within the chip itself to ground (about 16 ohms). I never expected this.

Just to note, Gary and Scott at Elecraft Support provided much =
information that helped me to finally track the problem down.

If you ever have a similar problem, use the Relay Table on the first =
page of Appendix B.  It provides what relays are to be closed for each =
band.  The nice thing is that they are latching relays, so when you turn =
off the power they stay in the same state.

On the good side, it proves that many K builders can learn to repair =
their own rig.  I also learned a lot about how the signals propagate =
through the K2 and how they don't too. ;)  I doubt that I could have =
ever located a problem like this on my TS-850.

John - KI7V



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