This converter has coils according to the reception and converted frequency bands. We found it in the October 1989 Radio Electronics magazine in an article that teaches its construction.
This circuit is from a 1967 documentation. It consists of a sensor for memories used at the time....
We found this circuit in the November 1992 issue of Radio Electronics magazine. The circuit has...
Found in EEE documentation, this circuit can have the duration and frequency adjusted separately....