George - I've used LP Bridge and LPB2 with my KX3 #5539. Both appeared to work fine for me. I first was doing it on Win/XP on a Mac under VMware Fusion, and now am running LPB2 on WIn 8.1 on the same Mac and the current Fusion. And, as Barry noted, use the K3 entry - works fine. Jim / W6JHB