RE: 4-in-1 Rx crystals?
DougT, In answer to your question, simply put, the answer is no. On the F-40, Walkera, and other identical choppers that use the 4in1 like they are set up, only those transmitters will work. That is because of their screw ball way of modulating the signal. Another radio transmitter will not work even if on the same freq. There are several of the guys that are using different transmitters, but in order to do so, you must change the 4in1 to something like an esky or eflite 3in1 then add the other receiver (Futaba, JR, Airtronics, etc). I hope that this wasn't too confusing. I know that sux, but that is the way with these beasts.