NBFM or Attenuated Bandage Frequncy Modulation is acclimated in this 27 MHz fm transmitter circuit schematic. This circuit is an appliance by Motorola MC2833 – VHF transmitter with FM accentuation and attenuated bandage in a distinct chip. The achievement ability is 10mW (+10 dBm) and the advantage is 10 – 20m.
P1 is acclimated to acclimatize microphone addition and P2 to acclimatize the deviation. Remember that this 27MHz fm transmitter use NBFM with best 5KHz deviation, this beggarly you accept to use an nbfm receiver to access abundant audio level.
The transmitter is accessible to adjust: trim C9, C9 and C18 for best achievement ability on a bogus 50Ω load. Then accept on a 27MHz radio receiver and acclimatize P1 and P2 untill you access the best modulation. X1 = 27.005 MHz quartz
