I would like to know if a buddy box system can consist of a futaba 2.4gmaster and a futaba FM slave? Thanks!

Yes it can. I am currently teaching my wife to fly using a Futaba 7C 2.4 as the master and a Futaba 4YF FM as the slave or trainer radio. Just be sure to keep the student or FM antenna collapsed and the FM power switch OFF. If you turn both radios on the receiver will not get a signal (not good). I am not sure the trims will be read by the receiver, but I have not noticed a problem with our trainer...a Midwest Aero-star 60.

The manual for the 2.4 master should tell you what buddy boxes can be used. It varies somewhat from radio to radio. For instance, Futaba's 6-channel FASST radio has a shorter list of acceptable buddy boxes than their 7-channel one does. So the answer to your question is yes, it can consist of this combination, but that doesn't necessarily mean you can use any Futaba FM radio as the slave with any Futaba 2.4 transmitter.

Great...thanks guys!!