I'ts more than just changing the crystal. The RF final has to be tuned to that crystal. If you changed just one channel, your final would be close, but from one end of the band to the next, your output would drop considerable, and what was transmitted, would not be clean. Back in the late 60's, I built a transmitter, receiver and five servos from a Royal Clasic kit. There was a lot of fine tuning that went on. I ended up borrowing an O scope from work to get it tuned correctly. That was in the days of citizen band, 27mhz radios. I think the FCC put the kits out of business.

Don