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Old November 5th 07, 06:47 PM posted to rec.radio.amateur.boatanchors
Lynn Coffelt Lynn Coffelt is offline
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First recorded activity by RadioBanter: Aug 2006
Posts: 9
Default BC-375 "surplus" w7kgv 1948


"K3HVG" wrote in message
. ..
Lynn Coffelt wrote:
Keith Martin, W7KGV used a rig that was a wonder to watch. Whole

garage
floor covered with used automobile batteries, charger working 24/7 for a

few
days, then the fun began!
BC-375 (from B-17's and B-24's) ran off 28vdc. Motor generator

turned
out 1000vdc for the rig. Basically an MOPA (remember????) with a VT-4C
oscillator and another for PA. (now the VT-4C's around are for

audiophile's
output tubes... some now referred to as 211's)
The MOPA transmitter worked on all bands, with proper tuning unit,

up
through 20 meters. Best output was on lower bands, 40 meters was Keith's
favorite, as his "off-center fed extended Zepp" antenna fit on his lot,

with
just a little over on the neighbor's lot.
Keith could contact "ZL's" in the evening, with reports ranging

from
336 to 589C. (Honest operators always included the "C"in the signal

report,
as the BC-375 had a distinctive "yooup di dit dit" which the "C"

designated
as a chirp, but was closer to a Yooup) It got really distinctive when

the
batteries ran low, and the filaments dimmed and the motor generator

almost
stalled on long CW dashes.
Keith eventually mastered a "bug" and increased his operating speed

so
more than one contact could be made before the batteries went dead

again.
Receiver was the venerable BC-312, which had a handy crank on the
tuning knob to follow the "state of the art" signals as they drifted

around
the band.
Some, who disliked drifting around on the bands, invested in a pile

of
FT-243 surplus crystals for other rigs, that didn't eliminate the

friendly
and reasuring "chirp", but didn't make drifting so much of an issue.

Old Chief Lynn, W7LTQ




Lynn, Not a few of us currently have BC-375's and '191's on the air,
regularly. With a bit of tweaking, FMing can be "minimized" but they
still drift. I'd like to find the xtal control mod that CAP used in the
50's for these rigs! Power supply wise, fortunately, currently there
are supplies capable of running (at least) the DY-88 24v dynamotor and
ac HV supplies are also around for both. They do present a very
impressive setup when the BC-348 or BC-342 are included, along with the
other SCR- accouterments. Look for some of these on the Old Military
Radio Net, an East Coast, early morning net on Saturdays on 3885.

One can't buy a new and complete SCR-284 for about $100 anymore, but
nice gear does show up from time to time. I was lucky and got a new
one a few years ago.... a time machine, to be sure! de Jeep/K3HVG


Wow! I'm going to have to try listening! I don't remember hearing a
BC-375 on AM phone!
Around 1959 I got mine new and complete for $50. Another young man had
just paid $75 for it and decided he didn't want it any more. After using it
a few months, I tore it up for parts and ended up with a push-pull final
amplifier. (using the VT-4C's, of course, and the plug-in coils borrowed
from another friend's BC-610) Always had some remorse about parting out the
BC-375 with it's tuning units, and antenna tuner, but sure had a lot of fun
building stuff with the parts.
The modulation transformer worked great in a much later (1958) home
brew 15 meter rig. Oh, how the bands rocked in those days!
Old Chief Lynn, W7LTQ