The radio microphone broadcast in the UHF band
The radio microphone is schematically shown in figure 1 works broadcast in the UHF band. The audio signal received by the microphone M1 is amplified by the transistor VT1, and is supplied to the varactors VD1, VD2 for frequency modulation of a high frequency generator.
High frequency generator wireless microphones performed on the transistor VT2. The oscillator frequency is set trimmer capacitor C5 in the range 88-108 MHz, if necessary, the oscillator frequency can be changed squeezing or stretching the coil windings L3. Power wireless microphones can be realized from the battery Krone, 9 volts. If the generator capacity exceeds 10 mW, the supply voltage should be lowered in order that the power did not exceed 10 miliwatt, how to use the microphones in this range with a capacity of over 10 mW are prohibited.