Hi there Alfred,
The best way I have found for dealing with this is not to reconfigure the standard messages. Just use the standard messages and the normal FT8 QSO protocol.
Have your macro panel on display 2 - so that “Gen. msg” and “Free msg” appear. In your Free msg field, have your SOTA reference, preceded by the word ‘SOTA’ - ie “SOTA G/SP-015”.
At the end of your QSO, you will send “M1EYP OE1SQA/P RR73”, then you will receive the final message from the chaser station: “OE1SQA/P M1EYP 73”. While you are waiting to RX this final message, check the “Free msg” box, and also Enable TX - then after the other station has sent 73, you will immediately send your SOTA reference.
The other station may acknowledge, but usually won’t, so you go back to sending CQ - you’ll need to remember to check the “Gen. msg” box during the RX cycle, otherwise you will just send the SOTA ref again!
When you have found a slot on the band and start calling CQ, that is a good time to self-spot, using the comments field to advise the datamode (because you can only spot the mode as “data”), the spot frequency and transmit cycle:
“FT8 - 1435Hz - TX even” (eg)
