In reply to M0JLA:
I made a cable that goes from a COM port and PC soundcard in and out connections using a DB9 and 2x 3.5mm jacks to the 817 6pin miniDIN data connector. The DB9 shell holds a tiny circuit which is used to translate RTS activity on the COM port into PTT signal. That will connect to any standard COM port. Of course COM ports are an endangered species now so I have a USB<>RS232 adapter. This one is fully supported under Linux and appears as /dev/ttyUSB0. I have fldigi set to PTT the 817 using RTS on /dev/ttyUSB0. Plug the USB<>RS232 cable in, plug the jacks into the PC, plug the DB9 into the other end of the USB cable, fire up fldigi and … digimode joy!
You need to play with the audio levels on the PC output mixer. These are fiddly to adjust. Also you have to play with the menu options on the 817 for the DIG mode. Do all this at home where you can check the TX signal is clean. In the field having checked the antenna is OK is plumb all the bits together and on a clear freq send PSK idles (i.e. just key up) and then using the 817 ALC display check the ALC metere shows no reading with the power level set to max. Job done!
The down side is that you cannot monitor your TX signal but if there is no ALC indication and is a power out indication you can be sure you are transmitting something.
Sounds harder than it is. Like everything to do with SOTA, it’s harder in the field than in the shack so practice setting up in the garden. Practice and practice then it will be easy in a howling snow storm at the top of a 10 pointer.
If you don’t feel competant at making a cable then email me off the list and we can discuss that as I have all the bits here.