K3HVG wrote:
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

The "Surplus Radio Conversion Manual" describes a modification to change
the BC375
oscillator into a buffer amp. It recommends using a external VFO and
suggests using
a SCR 274N or a BC459 or a BC696 (after conversion) as the VFO.

My copy is Volume 2 and is dated 1948.

Cheers
Bill K7NOM