High frequency VCO circuit with frequency from 3 to 30MHz

The function of the capacitor is to provide positive feedback between the emitter and base of the transistor
. The reactance of the oscillation frequency uses a low resistance value of several hundred, in order to prevent
changes in Tr and curve parameters from having an impact on the resonant circuit. This is a characteristic of this circuit . The resonant
frequency changes with the change of the coil V-, varactor = electrostatic capacitance of the tube.
    Using vcl and capacitor well connections can reduce the adjustment range of the varactor diode
. Because if the variable range t is expanded, the noise of the oscillation output will increase.
The oscillation output undergoes impedance transformation through a small-capacity capacitor, so that it is not
affected by the capacitance change.