My board also experienced the microphonic issue when first built.? I then did some case modes, rewired, added some snap on ferrites to dampen RF, tuned it up again, and over the multiple times connecting and reconnecting it went away.? I do not really know what was causing the issue.? I suspect dirt or oil in one of the connections.? My biggest suspect was the Raduino to uBitx connection.? In the process of connecting and disconnecting, as well as turning on and off the rig, I believe that I worked out the partial connection that was microphonic.? I never did find what the original cause was. It may still be lurking, waiting to jump up and get me again.
73
Evan
AC9TU
