FM vs. PCM trainer compatibility ??
I don't know about the Futaba models sold in Europe, but over on this side of the pond, as long as both radios are made by the same manufacturer, they should be compatible. For example, the radio that I have when I learned to fly is a Futaba 8UAPS (PCM). The other training Futaba radio that was available at our club was a Futaba Conquest II FM (production started and stoped in the 80's). My instructor set up my 8UAPS as a master and set the Conquest as the slave and we never had any problem. The Conquest did not even have on board battery and TX module. The power is supplied by the master.