circuit diagram of rc helicopter

Hi
I am trying to make my own transmitter that should work with 40MHZ OOK reciever for RC helicopter. I have found this circuit from net.
../imgqa/eboard/Antenna/rf-zqdbrbdc3wu.gif

but i dont understand this well or how to conver it to 40mhz.
can some one point me to a nice circuit for 40mhz band transmitter.
input to the transmitter is a digital PCM scheme

thanks

This is a VERY basic transmitter for OOK but it will probably work despite it's limited capabilities (output power, frequency agility, modulation). Replace the 27.145 MHz crystal with the wanted 40 MHz frequency (if you can find one), perhaps tweak some values for frequency tweaking and you're off to go.

thanks radio head. can you explain to me the two inputs B3 and B2 pins on the micro. As far as i can understand, PCM PWM both require only one digital input (i.e the data stream). so what is the other input for?


thanks

ok thanks
I understand it better now. The other line is just to turn the modulator on / off