|[AMRadio] Need ID Help for 1930's Transmitter|
n3rht at yahoo.com
Tue Sep 12 22:34:09 EDT 2006
As I mentioned on one of these lists, I found a 1930's
transmitter at the Butler hamfest. At first, I thought
it was homebrew, but looking it over, it's definitely
commercial or a kit. It's built to high standards and
there's no extra holes or poor parts choices or
unprofessional work of any kind. But so far I am
unable to identify it.
It was designed to have 3 19 inch rack panels--PS,
exciter and final (bottom up) But the PS is missing. I
guess if something has to be missing, that would be my
choice since I have a good stock of power supplies and
parts for same. The TX is all black wrinkle, chasses
panel and rack. The rack looks to be the original,
The final deck has a socket for a single tube with the
large, twist-lock base and 2 plate-cap-size
connections for plate and grid caps. Not many tubes
fit that description, so I am thinking maybe an 810
goes there? The Eimac tubes are out because they used
a pin for the grid--not a full-size plate cap. The
final deck has a filament transformer (I haven't
checked the voltage yet) and 3 large coils--one is
copper tubing, one is a plug-in type with center link
that looks something like the old B&W "B" coils and
the third one is on a large EFJ ceramic coil for under
the chassis. Two of the 4 steering-wheel type knobs on
the front are labeled ANTENNA so I think the final
incorporated some sort of antenna tuner. The other two
are labeled PWR AMP GRID and PWR AMP PLATE. The
variable caps on the final deck are all Cardwell. The
final deck has 2 meters, Triplett 0-100ma and 0-300ma.
The exciter has a 47 xtal oscillator driving an 807
buffer and what I assume should be an 807 output tube
(but it came with a 5933 in that socket). It has three
4-pin plug-in coils mounted on standard Hammarlund
1.25 inch forms, one in front of each tube. The
exciter also has 2 meters. One is a Triplett 0-100ma
that can be switched into 5 different positions of the
exciter circuit. The way this switch is implemented is
one of the things that makes me think this thing is
commercial--each connection is implemented on a 1/4
inch jack and the wires from the switch go to plugs
plugged into each of these jacks. The other meter is a
Weston 0-600V meter that was probably a repair job--it
has multiple scales on it and looks like the meter
from an old VOM. The 3 variable caps on the exciter
deck are all Hammarlund. They have knobs with metal
skirts with dial scales on them and are not labeled.
In general, the wiring is simple and high-quality.
Mica TX caps are used throughout, along with National
RFCs and EFJ parts in all the right spots. All the
parts are name brand.
So that's the whole story. If you think you might be
able to help ID this rig and you'd like a look at it,
please send me an e-mail and I'll send you a picture.
I've already checked Moore's book and it's not in
there. The next step is to go rooting through all the
magazines but maybe someone will recognize it before I
have to do that.
73, Don Merz, N3RHT
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