FM modulation signal modulation and transmission circuit

Shown is an FM modulated transmitter circuit . This circuit is mainly
composed of Kolapu oscillator VI'l, buffer amplifier VT2 and output amplifier. This circuit has the characteristics of high oscillation frequency stability and can be used to transmit modulated signals .
    The audio signal (AF) is added to the negative terminal of the varactor diode via the coupling capacitor (Ol UF) and the inductor (2 mH). When there is no signal input
, the junction capacitance of the varactor diode is the initial value and the oscillation frequency is 90 MHz. When the audio signal voltage is added to the varactor diode, the junction capacitance of the
diode controlled by the audio signal, so the oscillation frequency modulated by the audio signal . The VT1 emitter outputs the modulated oscillation signal, which
passes through the output amplifier VT2 and then is sent to the transmitting antenna through the transformer.