Thanks for the good advices and for the schematics. I found the problem... a beginner mistake (shift of a ribbon cable) and everything's fine now . Best 73 Nicolas -- View this message in context: http://elecraft.365791.n2.nabble.com/KPA-455-not-very-well-tp6943877p6944196.html Sent from the Elecraft mailing list archive at Nabble.com.