[HBR] HBR Dials...

[hbr@mailman.qth.net]

In a message dated 3/16/02 4:54:24 PM Eastern Standard Time, 
gswynar@durham.net writes:

> Greetings to the Group from a New Subscriber...
>  
>  An absolutely STUPID question, I'm sure, but where in the world do
>  contemporary builders of HBR receivers find all of those N.O.S./N.I.B.
>  "Eddystone 898" dials these days...?

Apparently a lot of those dials have been hoarded for many years. They show 
up on eBay fairly regularly. I used to see them quite regularly at hamfests 
around here (EPA) but haven't been to a 'fest in several years.
>  
>  And what are they getting them for in terms of $$$...?

The highest price I ever saw was $280 (not a typo) for a mint one on eBay. 
$50-100 is more like it. 
>  
>  They sure are good-looking!

They are nice dials but have some quirks:

- They really need a high-quality coupling. There's a Millen coupling that is 
a form of Oldham's coupling that is recommended. I think the number is 39016 
or 39006

- The output shaft is way above the input knob, requiring a subchassis or 
other method. Careful mechanical and chassis design is needed to avoid 
backlash. Need 
to cut several odd-shaped holes with good precision to mount it.

- The dial has is a combination of pinch-drive, gears and strings. The little 
round 0-100 dial visible through the window turns in the opposite direction 
of the knob.

But they do look cool.

I have found that the very best easily-available dials/drives for homebrew 
projects 
are to be found in WW2 surplus. Only problem is that you get an integrated 
capacitor/drive assembly. 

My favorite is the capacitor from a defunct BC-221 or LM freqmeter. These 
have a 
100:1 gear reduction drive and are about the best quality imagineable. Next 
come the capacitors in ARC-5 transmitters. Also useful are the capacitors 
from TCS receivers. 

73 de Jim, N2EY