[Elecraft] KPA RFI problem

[Ron W3ZV]

First, a thank you to everyone who has taken an interest and provided information on my problem.

In an attempt to quantify the problem, I sent Jack W6FB a copy of the fault dump on the KPA500. I sent Dick K6KR, the trace he requested from the KAT500. I also sent him the information he requested, from the KAT500. If those prove helpful, I will share the information.

Tuning solution at 25 watts on 24.968MHz

capacitance 104 pf
inductance 340 nH
vswr 1.17
bypass vswr 6.17
capacitors on antenna side unchecked.

While going through the trace exercise for Dick, I set the K3 to produce a dead carrier and then  slowly increased the drive from 10 watts to the point where the amp showed 500 watts output with no fault. Thinking the gods had smiled on me, I switched to sub, set the power to give 400 watts, started to call CQ and the amp faulted. I did not capture this fault so I started another trace and slowly increases the drive power while calling CQ, and got to 500 watts peak output with no fault. I then set the drive to give 400 watts peak output, started a trace and began calling CQ. The amp faulted. I repeated the dead carrier sequence and let it sit key down for ten seconds. No fault.

I am not sure if this is useful information or just a confirmation that the faults are unpredictable.

Ron W3ZV