I received my 6400 today. Using SmartSDR 2.4.9 on a Windows 10 computer. I hooked it up and all went fine until I tried to transmit using the FHM-2 mic. No transmit at all. It shows output using the ATU. Contacted a local Ham who has the 6400. We tried everything he could think of. Used all the setting he was using on his radio, still nothing. Does anyone have any ideas? I did open a Help Ticket.. Frustrating to have a brand new radio that does not work.