Don, Thanks for the suggestions. I am thinking of putting the outputsignal from the symetrix 528e microphone amplifier to c20 on the ksb2 board so I will bypass U3 and let the signal go direct to u5 NE602 and that way found out if u2 is bad. I will come back with the result. 73 Mike sm3xgm -- Sent from: http://elecraft.365791.n2.nabble.com/