[Heathkit] What is a Harmonic Drive Part # 467-1?

[Chris Codella, W2PA]

Bob is right.  The whole thing is platic.  The knob itself snaps onto 
the knob housing.  The knob skirt is simply decoration that covers the 
dark green plastic skirt.  The skirt doesn't actually rotate when fixed 
properly.  No amount of fiddling with it would eliminate the backlash 
for me.  It's not really backlash (which usually means the dial snaps 
back in the opposite direction from the way you've been turning) - it's 
more like "play" or "slippage", where, after tuning in one direction, 
tuning in the opposite direction produces no effect for a little ways.

It goes together like this (working outward from the front panel): dark 
green housing, then decorative metal skirt, then flexible inner spline 
gear with the "cup" pointed toward the front panel is slipped over the 
shaft and the inner, toothed part of the housing, then the knob is 
snapped onto the housing by just pushing it in.

Quite a few people (including me) replaced this drive with the one that 
Swan used on their transceivers.  It's basically the same kind of drive 
as is used on the HW-101, but has an extra outer knob-ring that you can 
grab and rotate for a 1:1 tuning rate. 

73,
Chris, W2PA

Bwana Bob wrote:
> The Harmonic Drive was the original vernier tuning drive used on the 
> HW-100. It was only used on this radio. It was a very simple mechanism 
> with a plastic flexible spline gear that attached to the VFO capacitor 
> shaft. The internal teeth on the spline gear meshed with teeth on the 
> outer knob housing, which was fixed to the front panel. Cams on the 
> tuning knob pushed against the spline causing it and the VFO shaft to 
> rotate. It was reliable, but tended to have a lot of backlash unless 
> one tinkered with it. When Heath replaced the HW-100 with the HW-101, 
> the dial drive was replaced by a more conventional set of 
> series-connected planetary ball drive ("Jackson Drives"). Heath 
> published instructions for converting an HW-100 to an HW-101. This 
> involved some pretty extensive rework.
>
>                     73,
>                     Bob WB2VUF
>
> jeremy-ca wrote:
>> Its a knob with a seperately rotating skirt but I'm missing the 
>> intended application nor do I understand how it works!?!
>>
>> Carl
>> KM1H
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