This circuit was found in an American 1980s documentation. The transistorized step is the receiver's last IF and the diode is the receiver's existing detector.
The circuit shown is from an old European publication. In it we have the way to activate a relay...
We found this circuit in a European publication from the 1990s. Transistors are still common types...
This circuit was found in an American documentation and can be added to common amplifiers of any...