Found in 1968 Mullard documentation, this circuit uses period components. The transistors are matched pairs and the sensor is an Indian photocell of the time.
This field strength meter for the 11-meter range was found in Radio Electronics magazine from...
The output stage of this amplifier can operate at high voltage. The transistor must be a high...
This article is from an old publication from 1978. The transistor can be a BC548 and the power...