Explainer: The FRG-7's Wonderful Wadley Loop

The famous Yaesu FRG-7 receiver used the ingenious Wadley Loop. What is it and how did it manage to keep the receiver so stable? Learn more here as I run through a spreadsheet simulation.
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[@w2aew]

Thanks Peter - I love the FRG-7 too. I've done a few videos on it on my channel too - including a "how to use" video, and one that goes through the architecture. Thank you for the mention!

[@wa7215]

As the old saying goes, ..”one ‘picture’ is worth, a thousand words”
Well done, with your ‘visual, spreadsheet’ explanation, of how the ‘wandering’ VFO frequency error, is negated, through the use of a lower, and crystal-locked, difference, frequency, being derived through the lower mixer, from the same, original single ‘wandering’ output, from the first VFO. 😉

[@acestudioscouk-Ace-G0ACE]

So that's how it works! Thanks Peter.

[@MirlitronOne]

Nice one, Peter. I've been meaning to model the Wadley Loop in a spreadsheet for some time, but couldn't figure out a good way to lay out the calculation - yours does the job very clearly. It's a very clever system but you need hands-on experience of the FRG-7 to appreciate it fully (preferably with three hands!). Thanks de M1GWZ.

[@Steve-GM0HUU]

Spreadsheet is a good idea Peter. I still have an old RACAL RA117E that uses the Wadley Loop. Many years ago I remember pouring over the manual to figure out how it worked. So long ago I had forgotten. Thanks for the reminder.
Now I am wondering if NE602 mixer ICs could be used to make a slightly more modern version of a Wadley Loop HF receiver.