Well, I messed around with this last night ... The problem I am having is that I purchased the cables from Elecraft for the Radio side of things ... this is the cable that goes from the AUX/MIC of RR to the rear PTT and Rear Panel MIC of the K3. At the control side, I am able to use the serial communications to remotely control the K3 and can activate PTT via software, but no audio is ever passed when I do that. What I discovered is that if I take the Heil adapter and use a manual PTT plug I can activate PTT on the K3 and then audio will go to the radio end. So the software PTT is not working properly. Any ideas? Is it that I cant use the Rear Panel mic at the radio end with the Elecraft cable and the AD-1-KM unless I manually PTT?