[Elecraft] MIC + Line-In Feedback Noise

[Bud Governale, W3LL]

Thanks to both Eric K3NA and Rich VE3KI, I now have Line-In working.

That leads to a new related issue:

When MIC + LIN is turned ON I get feedback from somewhere when I key with the foot switch in SSB without saying 
anything.
If I turn MIC + LIN to OFF the feedback is gone.
I closed N1MM just to be sure it wasn't causing a problem. It wasn't, the feedback was still there.

Any suggestions?

73,

Bud W3LL
w3ll at arrl.net