[Elecraft] odd happening with KPA500

[Tony Estep]

My K3 and KPA500 have lived happily for months, ever since their first
blissful night together. But today something bizarre happened, and I'm
just wondering if anyone else has seen this:

I had a couple of QSOs on 15 meters, with everything working FB as it
always does. But then a little later when I tried to call a DX station
on CW, the amp faulted, claiming PWRIN HI. I reset it, verified that
the power in was 30W, and tapped the key. Same result.

Then (here's the bizarre part) I reset it, pressed TUNE, and advanced
the power from its normal tune level of 8W up to 30W; the amp put out
500W, no problem. Then I set the K3's transmit output power to 3W and
tapped the key; PWRIN HI fault.

So in other words it tolerated 30W of drive if I applied it via the
TUNE button, but not even 3W of drive in normal transmit.

I checked the antenna, the grounding connections, and everything else;
nothing had changed from the configuration that has been working
perfectly on all bands for months. Then I tried the amp on all other
bands, 80 thru 10. All operations perfectly normal.

Finally I powered off the amp and switched the rear 0/1 switch off,
and fired it up again. 15 meters returned to normal, and all is well.

My guess is that that the PIC chip is addressing some volatile memory
where intermediate values are stored, and a memory location pertinent
to 15 meters only got scrambled by something. But that's just a guess;
actually, I dunno what happened, but I sure hope it doesn't happen any
more. Anybody have any thoughts?

Tony KT0NY


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