Audio high frequency generator circuit

The audio and high-frequency signal generator is shown in the figure. It can output audio signals, 465kHz mid-spectrum amplitude signals, and 52.5Hz4-16Q5kHz
high-frequency amplitude modulation signals. VT1 and others form a high-frequency oscillator, and the oscillation
frequency is composed of G, L. Decide. The audio signal generated by the music integrated block
is output from the jack XS on the one hand, and
modulates the high-frequency signal through R and c1 on the other hand to generate an amplitude modulation wave. Potentiometer
RP is used to adjust the size of the audio output signal. Medium and high
frequency signals are directly radiated and output by the magnetic antenna. The size of the output signal can be adjusted by changing the distance and relative position between
the signal generator
and the receiver. The magnetic rod in the magnetic antenna has
70 turns around Wl and 20 turns around W2. G is the tuning capacitor. Changing
C3 should cover 460kHz-1610kHz. Otherwise, it can
be achieved by increasing or decreasing the number of Wl turns. Y is the bias resistor, adjust Yong so that the VT1 collector current is 0.8~1. 2mA.