Radio local oscillator circuit

Shown is the local oscillation circuit of the radio . There are waveforms of various frequencies in the sky, such as 1386 kHz, 999 kHz
and 666 kHz of the medium-wave station. These waveforms are received by the antenna into the radio frequency amplifier. The waveform frequency of the intermediate frequency amplifier is 465 kl-k. At this time,
the local oscillator is required to provide the local oscillator signal, so that the waveform signal received by the radio frequency amplifier and the waveform signal of the local oscillator are
calculated to obtain an intermediate frequency of 465 kHz. Signal. For example, if the radio frequency amplifier receives a waveform signal of 1386 kl-lz, the local oscillator provides
a resonant signal of 1386 kHz + 465 klh 1851 kHz. After the mixer, 1386 kHz, 1851 kHz, (1851+1386) kHz and
(1851 -1386) kHz four signal waveforms, and then filtered to select the required 465 kHz intermediate frequency signal. When the radio wants to receive
a waveform signal of 999 kHz, the radio frequency transmitter and the local oscillator can be adjusted so that the local oscillator provides a resonant signal of 999 kHz + 465 kHz = 1455 kHz
, and then the mixer generates another four A waveform signal and filtered out a 465 kHz intermediate frequency signal.