[Elecraft] KXAT1 intermittent relay drop

[Alan Jump]

I inherited a KX1 about three weeks ago, and until this afternoon it had
been performing flawlessly on a random-wire antenna and counterpoise.
Today, I was trying to call CQ on 20m, and after running a tuning cycle
and seeing a 1.2:1 match, I started calling CQ as usual. In the middle
of sending a character, the unit "clicked" and the background noise fell
off enough to darken the S-meter bar display. I ran another tune cycle
and saw a 9.9:1 match, but the background noise came back. Yet another
tune cycle and the radio returned to the 1.2:1 match. The displayed
output power didn't vary, showing 1.4 watts.

I got curious and opened the case. Looking at the tuner board, I saw one
relay (K7) that looked like a corner had been trimmed away. I can't tell
if it was intentionally done by the original builder to afford clearance
with a main-board toroid, or if it was heat damage. I looked through the
documentation I was given along with the radio, and I don't see anything
in the KXAT1 manual that calls for trimming anything for clearance, so
my first instinct is a heat issue. I'll be emailing Parts to obtain a
replacement relay in the morning.

I've only been able to repeat the problem once, and it only seems to
happen when I'm running off my desktop 12V power supply. It doesn't seem
to happen at all when running on batteries. My question is...has anyone
else come across this? Is it a random component failure, or is there a
potential for a repeat failure after I replace the relay?

-- 
73 de N5ILN
Alan
alan.jump at gmail.com
NAQCC # 6139