CGr,

There really is not "compatibility" between brands. Some manufacturers do make RF modules that will plug into a different brand transmitter. In all cases, the RF link and receiver compatibility is tied to the module and that is brand specific. The transmitter is only sending instructions to move servos.

You can buy a Spektrum brand DSM2 module to fit a Futaba transmitter. It will only communicate with Spektrum and JR DSM2 receivers.

Hitec has a 2.4 ghz module that fits Futaba transmitters and may already have the one that fits JR module based transmitters. It will only communicate with Hitec Optima receivers.

Hobbico has a (Futaba FASST) module that fits THE PCM10, PCM10S, PCM10SX, PCM10SXII, 10X, 8103, 9103 and 9303 JR transmitters. It will only communicate with Futaba FASST receivers.

The XPS equipment in Vasek's link; plus the modules from Assan, Corona, etc may fit in various transmitters but they are still proprietary systems that only work with their own receivers.