This is an amplifier circuit intended for modulating transmitters. The 5-tube circuit is from an American manual from 1947. The power supply uses a transformer.
This S-meter circuit was found in a 1976 publication. The circuit is used to measure the signal...
Several versions of this circuit can be found on this website. This makes use of FETs that can...
With the circuit shown in the figure we have a frequency modulation which is produced by a...