[Elecraft] KPA100 Output Power Problem

[Jim Brown]

Hi Elecrafters:

My KPA100 is sick and I need help. The when 11 or above watts are requested, I get 100+ watts out. When 5 watts are requested, I get 15 watts out. The K2, without the amp, behaves as expected. I have done all voltage checks per Rev A manual and all is normal. All firmware is latest available.

I had blown the serial port and repaired by replacing RFC8 and U4. While I was waiting on parts, the KPA100 functioned OK. After the replacement, the serial port is OK, but the KPA100 is screwy. I replaced Q1 and Q2 thermal pads and rechecked the bias.

Any advice is appreciated before I box it off to Elecraft.

Regards,
Jim Brown, K5JAZ
K2/100 #2535