Wadley Loop

The Wadley Loop works by:

Unlike other drift-reducing techniques (such as crystal control or frequency synthesis), the Wadley Loop does not attempt to stabilize the oscillator.

Popularly known as the 'Frog Seven', it was one of the first commercial SWL receivers to utilise a triple-conversion superhet circuit with the 'Wadley Loop' system - although such an architecture had been seen in earlier tube radios manufactured for government use, most notably in the Racal RA17.