The German magazine Funk Amateur of April 2006 had a interesting design: (...)

The DK1HE "Superdipper" "Dipit"?. Yeah, it's a fantastic idea!. It's
like manually rotating a little forth and back the tuning knob, 400
times a second. A little drawback is its (understandable) complexity.
And it goes up to only 42MHz. The english version is in
www.qrpproject.de/UK/DipItUk.html
If I can't find an already chewed design, I may end up building this
thing, plus some ideas from the DUBUS VHF UHF Technik book by DL7QY,
reaching 1GHz but with the aforementioned amplitude clipping at low
end.
If this is NOT what you have, then I will gladly accept your offer!
Thank you for answering!.
Daniel Perez