See diagrams for K3 on SPE yahoo group. In fact, one only needs 4 wires: ground, TX of serial, PTT and turn-on. Works as well as it could. Ignacy, NO9E -- View this message in context: http://elecraft.365791.n2.nabble.com/K3-integration-with-SPE-Expert-2K-FA-tp7611739p7611759.html Sent from the Elecraft mailing list archive at Nabble.com.