Most things are easy to work out in FLDIGI, but I just tried working a station that was working RTTY split, listening 1 up. You can certainly do this via settings on your radio but FLDIGI allows you to set different rx and tx freqs too – which is easier as it’s just point and click:
- select the tx freq and press the ‘Lck’ button – this fixes the tx
- clicking anywhere on the waterfall after you’ve pressed Lck now sets the receive
Don’t forget to unclick Lck when you’re done.
I got this from the manual here (funnily enough).