PowerSDR KE9NS v2.8

I recently added an amp to my station and have been mostly using digital modes, thought I would try SSB. I have gone through the audio chain and I think it sounds OK in my headphones. The ALC comp peaks at .03 db. If I use the MFJ tuner the audio sounds about the same. I am running the signal to a 10 - 40 vertical ground plane rated for 1500 watts.

The problem starts when I add the Amp. I will use the tuner to adjust to the frequency and then adjust the tube Amp to the frequency. I have the power level set to 60 watts. On 40 as an example the tuner is showing an SWR of 1.0 and on the Amp, it is showing an SWR of 1.2. Into a dummy load the ALC comp is showing a peak of .03 db. Turn the Amp on now the ALC comp is showing +4 to +9 ALC comp when I speak into the mic. Sometimes just keying the mic will cause ALC comp to over load. The audio in my headphones is over modulated, scratchy and I might be hearing some clipping of the audio. I have tried with the tuner turned off and just used the Amp to adjust to the frequency and I still have the same problem.

Process of elimination, I think the Flex is fine but I do sometime question the meters. Both the turner and Amp are new and less than a year old. I don't think they are the problem. The antenna it's transformer and coax are both about 2-years old. I am running 12-gauge wire from each device to a central point and then to a ground rod. I think I am OK there. The amplifier is compounding a problem and I don't know what that problem is so that I can fix it. What am I missing? What do you suggest I check?

Thanks for your help. 73 Jack (AI6OI)

Problem fixed. As it turns out the problem was a non-grounded mic shield. Thanks to another operator I learned several of the transceiver manufacturers do NOT ground the microphone shield. Using instruction on the Heil website I was able to attach a 20 gauge wire to the shield and this solved the problem.