I've been asking about this my self. In the code is function button for different modes and functions. One is CW mode which requires the external use of a transistor to hold PTT for a bit while cw code in sent. Then after a bit it times out, unkeying the PTT.?
That's what I understood from reading the comments in the code. It seems to me if you can put the sound of your CW tone on a certain frequency by an offset so it can be heard by another on that frequency and you can hear them, then you are doing CW.
But the others don't think it's that simple. And I haven't tried it yet. I lost a month of experimentation, and traded it for a month of troubleshooting and repair, just to play with it now.
