Question about Futaba 9c 50 mhz output.
First, please remember, I'm not affiliated with Futaba in any manner any more. Next, please know i'm not trying to be argumentative. Believe me, i spent WAYYYY too much time working with this stuff when i was still at Futaba. This will be my last post on the topic, and please don't take that as 'blowing you off', but this hobby is supposed to be for fun now, and arguing semantics over regulations just isn't my idea of fun. :-)
"(b) An R/C transmitter which incorporates plug-in frequency
determining modules which are changed by the user must be certificated with the modules. Each module must contain all of the frequency determining circuitry including the oscillator. Plug-in crystals are not considered modules and must not be accessible to the user. "
Crystals in the US are secured in a holder, covered with a cap, or glued in place as required by FCC.
FCC most clearly states right here that yes, changing a crystal IS a change and is not allowed.
The US Futaba service center has a certification for radio service, including modification, which IS from the FCC and which is "policed" by the FCC. do I recall the type of certification, or even am I sure which head technician holds the license specifically? sorry, no.