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" 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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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

Richard Knoppow wrote:

SNIP

I don't know exactly when the VV was introduced but it
was made for decades.



Richard,

Thanks for the info, I will see what I can find. I have put up some
information and pics of the ones that I have at
http://www.radiowymsey.org/newsblog.htm . Mine with dials are the
original design - the earliest drive has 'patent pending' on it
whilst the rest have a patent number so I might be able to get a
date from that.


Charlie.

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Hi Charlie:

I suspect that the VV dials with the GE knobs are from the BC-191/BC-375
tuning units. They were made by GE and used the particular VV drive you had
phtos of (ceramic spacers). They probably began production in the late
1930s.

73, Colin K7FM

COLIN LAMB wrote:
Hi Charlie:

I suspect that the VV dials with the GE knobs are from the BC-191/BC-375
tuning units. They were made by GE and used the particular VV drive you had
phtos of (ceramic spacers). They probably began production in the late
1930s.

73, Colin K7FM



Colin,

Thanks very much for the info, it certainly looks as if you are
correct judging from the pictures I have googled of the two radios.
I also have one of the locking knobs shown on the BC 375.



Charlie.

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There may have been another distinguishing feature of the GE VV units. It
is all a little vague, but I recall that the shafts for the knobs on the GE
units were slightly smaller than the standard 1/4" shafts.

73, Colin K7FM

COLIN LAMB wrote:
There may have been another distinguishing feature of the GE VV units. It
is all a little vague, but I recall that the shafts for the knobs on the GE
units were slightly smaller than the standard 1/4" shafts.

73, Colin K7FM



Colin,

That's right, the shaft is 3/16 inch diameter - the 'output' are 1/4
inch, I assume in order to couple to standard variable capacitors.
But I think that may have been a standard feature of the VV as the
older ones I have also have a 3/16 inch shaft.


Charlie.

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