All is working well on receive and transmit but the buzzing is still present in the S-meter Mode. We have determined it is derived from U1 but I can not locate the culprit.....check all grounds on Xtals and check all solder joints but to no avail.....any suggestions would be appreciated. Looks like this one is going to Elecraft for bench testing.... Thanks, Steve J Harpole, DDS KQ4UB