[Elecraft] KPA500 Strange Operation

[James Bennett]

First, let me wish all a very Merry Christmas!

OK, now the problem. I have a KX3 and the full K-line: K3, P3, KPA500, and KAT500. I have a two position coax switch that I use to drive the amp with either the K3 or the KX3. When using the K3 (P3 powered off) all works perfectly. I can change bands by pressing the appropriate band button on the amp or changing bands on the K3. Doing either results in the amp display changing to the associated band.

But.... If I have the KX3 turned on and the K3 off, pressing a band button on the amp has no effect. The only way to change bands on the amp is to set the KX3 to the desired band and then tickle the amp with a little shot of RF. Now, the bad news. It does not do this all the time. Not 100% certain, but it seems to act like this if the amp has been powered off for a few hours. Just a couple minutes ago I was doing some sleuthing on this issue. After having the K3 online and sending RF, I tested this out and the amp subsequently behaved as it should after a K3 shutdown and KX3 startup. The amp changed bands with its own buttons or via RF from the KX3. Hmmm...

Very strange. Anyone (K6KR?) able to shed light on this unusual behavior? Not a gigantic big deal, but it does make me wonder what's going on.

73, Jim

Jim Bennett / W6JHB
Folsom, CA