A search of Nabble shows that this issue has been noted before. http://elecraft.365791.n2.nabble.com/KPA500-PR6-AUX-Cable-Pin-11-td7558085.html 73 - Steve WB6RSE ******************* "When I try to hook in the PR6-10 I use the CTRL line on the PR6 connected to Pin 11 on the K3 ACC jack. When I do this I can't cycle the PR6 or KPA500."