RE: futaba 6channel 2.4ghz rx compatible with 7ch 2.4ghz?
If your question is do the transmitter and receiver have to have the same number of channels, then the answer is no. A seven channel transmitter will work with a six channel receiver. A seven channel receiver will work with a six channel transmitter. In each case, however, you would only have six channels available and would in each case be limited in the controls available(aileron, throttle, etc.).