[Elecraft] K2 w/KPA100 power resets after approximately 2 hrs of turn-on time

[wa4ywm]

I originally posted this in July and I still have the problem. The issue is
as described below past the dashed line. Note that the issue happens even if
I haven't been transmitting.

Don Wilhelm helped me attempt to troubleshoot the issue. We eliminated the
base K2 as the source. After that, at Don's suggestion, I installed the
KPA100 upgrade kit - no success. At this point we gave up.

Recently I replaced D16 & D17 on the KPA100 after reading about similar
problems caused by the damaged diodes. Still no luck.

Has anyone out there had a similar issue? 

73,
Jim Elmore WA4YWM

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I have a K2 serial no. 4729 with the 100W amp which I have been using for
almost 10 years.

It recently developed a problem with the following 2 symptoms:

1. After operating for some time (perhaps 1-2 hours) the Tune function will
begin to display 1 W with a 1.0-1 SWR on all bands. It normally displays
22-23W with the correct SWR shown.

2. At the same time, if I attempt to transmit, the K2 will apparently begin
to draw too much current and it shuts down and re-starts. The Tune function
also shuts the K2 down at this point.

I observed the same behavior on a dummy load - to eliminate an antenna or
feedline issue.

I also left the power supply on while letting the K2 cool down to see if the
supply
was the source of the problem. Apparently not since the K2 would operate for
a significant time after turning the K2 back on.





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