[Elecraft] K3 distortion

[Dick, WN3R]

> 
> I have two K3's. One has a problem.

When I turn on the line input and advance compression, the audio becomes severally distorted. I am listening to the audio through the monitor and watching the output power on an external power meter. It might even sound like RF feedback. Without speaking into the mic output levels can be 80 watts or more.

Turn off the line input and it all goes away. Audio is perfectly clean.

I have completely isolated the radio to make sure it is a radio problem only. Test setup was a fully charged battery, a Heil microphone, headphones, and a dummy load. Absolutely no other connections.

Radio came back from Elecraft with no problem found,  but in all fairness, I did not know at the time that turning off the line input solved the problem. I discovered that by accident months later.

My solution is to connect the computer sound card throughout the front mic connector as I did with other rigs. I'd like to be able to use the rear audio connections again. 

Any ideas?

Thanks, Dick, WN3R