[Elecraft] QRO - KPA500 Failure

[Andy Durbin]

"On key down (input of 15W) the asterisk briefly displays, then display changes to 18.1, back to HV display on key up."

Are you saying the "HV" text in the display goes away or that it reads HV 18.1?

Normally the HV display continues to read the PA supply voltage regardless of whether the amp is keyed or not.  It would normally just change from approx 80 V to approx 60 V when keyed.  At face value the results seem to indicate a high voltage supply failure or a fault in the PA that is sucking a very high current.

What is the PA current during the brief period the KPA500 remains keyed?

What are PA voltage and current when keyed if the 60 V line is disconnected from the PA module?

Of course the safe plan would be to send it back but those are some of the test I would try if it were mine.

Andy, k3wyc