Gerry, I tested it on Snow Leopard as same as on High Sierra with 10.16.6.25 KX3 Utility and it works as it should. Which kind of drivers are you using please? ----- 73 - Petr, OK1RP "Apple & Elecraft freak" B:http://ok1rp.blogspot.com G+:http://goo.gl/w3u2s9 G+: http://goo.gl/gP99xq -- Sent from: http://elecraft.365791.n2.nabble.com/