Harsh Sidetone on QCX-20M With AGC On

Ernie Bailey - N2DGQ

I have read several topics about this on this forum regarding harsh sidetone and relating to RF feeding back to speaker.  But in my case when I turn the AGC off the harsh side tone goes away.  I have a QCX-40M rig with AGC and there is no harsh sidetone.  I am using a powered speaker. And I have a Rev-3 rig. 

I have removed the AGC board and reinstalled it.  Adjustment of the AGC potentiometer does not seem to remove the harsh side tone.  

It's not the end of the world as there does not seem to be as many strong signals on 20M as there is on 40M.  But I'd like to have the AGC on.  

Any suggestions? 

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