I have this connected to my FT897 and to work DM780 you will have to go into C:\Programs\HamRadioDeluxe find DM780 and make a short cut to your desk top. Then, when you have it up, go into config and tick PTT through the com port that your interface is using. To use HRD i think you will need a CT-62 Lead into the CAT port on the back of the radio. But doing this I need to use two ports on your PC.