This circuit was found in a 1945 publication. The circuit has 4 tubes and can operate as a multi-test and a signal tracer with listening in a loudspeaker and also a radio receiver. Inputs are for audio and RF signals.

This circuit was found in a 1945 publication. The circuit has 4 tubes and can operate as a multi-test and a signal tracer with listening in a loudspeaker and also a radio receiver. Inputs are for audio and RF signals.