LC tone generator for 1750 Hz for repeater keying
This tone call oscillator works with an LC circuit. The generated frequency is approximately sinusoidal and changes within the supply voltage range of 5 to 15 volts by less than 10 Hz. The voltage divider is dimensioned so that the output voltage can be matched to a microphone input.
The resonant circuit capacitor and the coil were soldered out of the 1750Hz call tone unit of an old two-way radio, so that their dimensioning did not need to be taken care of.