This simple receiver of two transistors for the 80-meter range was found in an American documentation from the 1980s. The transistors admit equivalents and the antenna must be long.
The circuit is from 1968, but we can use a modern one like the 741. The symmetrical power supply...
This circuit was obtained from an English magazine from 1981. The magazine no longer exists, but...
The circuit shown, found in French documentation from the 1970s, functions as a variable...