DIYbanter - View Single Post - RC transmitter transmits on first harmonic

Daniel

a écrit :

FWIW.. not that it helps:

144 MHz is the American 2m ham band, for which I have a license.. I
left that out. It's not exactly in the band plan for RC aircraft but
it's not like I'd be causing real aircraft to plummet to the earth.

Thanks for the tip about capacitance. There is a trimmer cap on the
board right next to the crystal, I assumed it had something to do with
tuning the feedback but I don't even know what kind of oscillator it
was so I was hesitant to just start twisting knobs.

It is very difficult to get schematics/ service manual in the RC hobby.
Some kind of trade secrets, maybe.

Probably the trimmer cap is there to adjust the frequency shift at
+/-1.5kHz from center frequency. This is the FSK system used in RC
equipments.

Did you used the correct replacement transistor?

Try posting on http://groups.google.com/group/rec.models.rc.air .

Daniel