Lost Transmiters>>>>help!!!!!!!!
Airtronics and JR both FM shift in the same direction, and are compatible (channel numbers may change though)
Futaba and Hitech both shift in the same direction, but opposite JR and Airtronics. So Futaba and Hitech are compatiable with each other, but not with the two above.
Hitech has a transmitter that is switchable from JR/Airtronics to Futaba shift, so it can drive any FM receiver out there.
The above applies to FM only.
PCM is a differnet ballgame, no one is compatible with anyone else there (as far as I know).