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Friday, May 6, 2016

Polyvaricon Reduction Drive

Oh man, we need more of these.  Many more.  Unfortunately, this may be the only one.   I pulled this out of an old piece of mystery-gear given to me back in 1994 by my friend Pericles HI8P.   Look at that:  dual turning rates, solid construction, and very small.   This device seems destined to go into my W4OP-built Barebones Superhet (in the background).


  1. Cool! My next rig will have a flywheel mechanism. I've been obsessed with that lately/

  2. Commercial product? Link to source?

  3. Dex - you talking to me? I'm trying to figure out how to use the flywheel from an early 40s Zenith, so I guess it is a commercial product, hi.

    73 de Steve N8NM

    1. No, Steve. That was a query on the reduction drive, Lots of product used flywheels, mostly on string-to-drum, but they were simple - not 'mechanisms', and largely household multi-band BC/SW sets where a rapid transition of the span was desirable and bandwidth/accuracy (AM) not particularly critical. SSB/Ham is a different story. Good luck! :)

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  5. What about the reduction drives in old UHF tuners? They were pretty horrible, but that was something commonly available at one point. I don't remember if there was any eduction at first, but if you backed up, the reduction would kick in. Annoying but it got you to the approximate place fast, then slowed down to get precision.

    It's a little late with varactors taking over, but there was a time when the average AM/FM portable's multi section variable capacitor included a small reduction gear. If analog portables were still common, that would be something to watch for, but they aren't that common anymore.


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