Thanks for the pointers, I have gone through the download/setup etc with a fresh card and I am still experiencing a problem. It'll be something simple I imagine, perhaps because I am only running dummyrepeater, as an example. Incidentally my Pi3 card did not run on a Pi2B ; I'll keep looking.
I double checked the baud rate and I get an error ( wrong baud rate ) when I enter 460800 so my ThumbDV is an " old " one and it is at /dev/ttyUSB0
My first install was with Compass lite on which I had Direwolf running; I followed the install instructions to use dl5di github and ambetest3.py ( maybe not the correct name as typing from memory <smile> ) responded correctly although dummyrepeater needed a GUI installed so I downloaded the Compass GUI. I'm assuming the ambeserver runs on its own and doesn't need dummyrepeater, unfortunately I get no response when running python ambesocketest.py.