[Elecraft] KAT500 failure

[Andy Durbin]

My KAT500 has stopped communicating with my controller and does not power up normally.  With PC data cable removed, when I pull and replace the power plug the KAT500 powers up with a relay clunk and with MAN and ANT 1 LED lit. All front panel buttons are unresponsive.  The same thing happened a few weeks ago but it recovered after disconnecting and re-connecting power.

If I leave it disconnected for a while sometimes the KAT500 will power up and allow the mode to be changed once or twice then it locks up again.  I was once able to connect to the Utility but normally Utility does not see the KAT500.  Most of the time KAT500 powers up showing MAN and ANT-1 and is completely unresponsive.

I took a break from composing this email and powered it again.  This time I was able to cycle the mode and antenna several times before it locked up showing MAN and ANT-3.

AZ is warming up and room temperature is nearly 29 deg C.  I'm suspecting the KAT500 has a thermal problem.  Does anyone recognize these symptoms and know a probable cause?

Thanks and 73,
Andy, k3wyc