Mike: Suggest changing fuses in input fuse block. I have experienced an intermittent fuse problem in other equipment in the past that produced very puzzling symptoms. 73 and good luck, Dan AC6DM -- View this message in context: http://elecraft.365791.n2.nabble.com/KPA500-problem-tp7614144p7614230.html Sent from the Elecraft mailing list archive at Nabble.com.