Changing tx crystals?

[foufly]

Some quick advice please guys. Can I change a Tx crystal ,40 mhz to 35 mhz in futaba transmitter ,without retuning it  and without problems? My impression was it can't be done......?

[electrotor]

Physically it can be done and the tx would work after a fashion. However the tx circuitry will be designed and tuned to work optimally on 40MHz. Even retuning will not necessarily work satisfactorily. It's not just about spot frequency and power output. You could end up with a tx emitting harmonics of 35MHz which the 40MHz circuitry could not adequately filter out. In addition the spot frequency on 35MHz may occupy a larger bandwidth than the regulations permit and you could end up affecting the channels either side of yours.
Bottom line - don't do it.

[Coyote]

40 mhz is for surface rc control, not airborne use so its not to be done anyway

[foufly]

Thought not, thanks.