This circuit for the 40 MHz band was published in Radio Electronics magazine in December 1957. Its purpose was to monitor the signals of the Russian satellite launched at the time.
This circuit with the NE602 was found in the February 1997 Electronics Now magazine. The NE602...
We found this circuit in Radio Electronics magazine from September 1959. The circuit has different...
Found in a 90s Radio Electronics, this circuit uses an AD590 or AD592 for remote temperature...