This interesting reflex receiver used a different component, which at the time was showing up. The receiver is from a 1924 documentation and used a sodion tube.
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...