[Elecraft] K3 Erratic SSB Power Output

[Terry Schieler]

Jack,
I just sent my K3 (474) off to Elecraft service after wrestling with that same problem.  My TX output was suddenly all over the place.  The K3 power out bar graph showed 25% lower power than I had dialed up, but good, calibrated external watt meters were showing 40-50% higher power than what I had set on the K3.

After reading your post I wonder if a new version of Firm Ware might have caused something to go wack-o.

Terry W0FM


-----Original Message-----
From: JACK WHITE [mailto:g8dx at btinternet.com] 
Sent: Sunday, July 21, 2013 2:12 PM
To: elecraft at mailman.qth.net
Subject: [Elecraft] K3 Erratic SSB Power Output

Hello K3 Reflector.


I have an issue with my new K3/100 #7482. On SSB the peak power output isn't stable. The SSB power output fluctuates about +/- 15% of where it is set, but occasionally spikes to much more. The issue is on all bands but seems worse on 12/10m. I have tested the rig connected straight to a 1kW Bird 50ohm load and have tried 2 different linear power supplies. The problem is present using the two tone test feature, microphone or direct PC audio fed into the rig. 


The real problem is: I set up my Acom 1000 at the legal limit here (400w) and the power output is all over the place, sometimes 150w, then maybe 500w, then 300w, then all of a sudden the power can spike to 1kW+. I operate mostly CW. Things seem more stable on CW, but compared to my previous Jap rigs (FT1000MP, FT990, TS850) etc, the power output is very difficult to properly regulate. On my previous rigs, I'd set them up to drive the Acom to a certain power level and they'd run for hours rock solid without a peep.


I've had an e-mail exchange with a friendly Elecraft Guy which resulted in me redoing the TX Gain calibration, he said the numbers looked good, but the problem persists. I am curious to see if anybody else has this issue and knows of a fix? As it is, the rig isn't much use to me.



Cheers



Jack G8DX