"M0WYM" wrote in message
...
Having obtained a number of these National drives and
dials I was wondering if anyone knows of a good source of
information on them. I have googled up a number of sites
that mention them in passing but I would like to get more
information. Some of the dials are pre WW11 and made of
Bakelite whilst later ones have black aluminium dials.
They all have the velvet vernier planetary reduction
drive.


Charlie.

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M0WYM
www.radiowymsey.org

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Look for old catalogues. Also, the ARRL has all back
issues of QST on line. National was a heavy advertiser in it
so you can probably find the dials there. They are
definitely in the catalogue section of the ARRL Radio
Amateur's Handbook. The original Velvet Vernier was a plain
dial with the calibrations on the knob skirt. The later
Type-B was an enclosed dial. The original had a fixed
reduction ratio the later ones have a clever moving pinch
arrangement so that the ratio can be changed with a small
lever under the knob. both the skirted and dial types came
in at least two sizes and some other variations.
I don't know exactly when the VV was introduced but it
was made for decades.


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Richard Knoppow
Los Angeles
WB6KBL