[Hallicrafters] Grommets for tuning caps

[Mark Shaum]

----- Original Message -----
From: "Roger D Johnson" <n1rj at adelphia.net>
>
> I'm not sure exactly what function these grommets served. All of the
> high end receivers I've seen have the tuning capacitor bolted firmly
> to the chassis. I replace the old grommets with a stack of washers the
> same thichness.
>
> 73, Roger

I have several low to mid range receivers of various brands with the
tuning capacitors mounted on shock mounts of some form.  On the SX-43
that happens to be open in front of me, the main tuning capacitor is
shock mounted but grounded to the chassis with several copper straps.
The bandspread capacitor, however, is firmly bolted to its subchassis.

I surmise that the shock mounts are to minimize microphonics and/or
assist with control of backlash in the tuning mechanicals.  One little
All American Five genre set I have with a built in speaker howled like a
banshee when I tightened up the screws going through the (dried out)
rubber grommets a bit too much.

73! - Mark
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Mark Shaum K9TR
email: k9tr at dtnspeed.net
http://www.qsl.net/k9tr
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