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 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

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

"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

All, I've looked over the external driver modification and have chosen
not to do it owing to the mods required to the TU's... at least at this
time. I know for a fact a rather simple xtal control mod was done to
these rigs for CAP. Our Wing had a number of the BC-191s and they
worked OK into the early 60's. Unfortunately, those who would have been
privy to the technical aspects of this don't appear to recall or aren't
around, anymore. All I can remember is that there was a little Bud Box
attached to the lower left side of the transmitter. There was no ARC-5
or anything else of consequence, outboard except I seem to recall that
this crystal oscillator drove the VT-25 (10) oscillator tube and
something about only one wire/connection associated with feedback in the
TU being disconnected? Does that seem plausible? That's all folks........

Jeep/K3HVG

"K3HVG" wrote in message
...
All, I've looked over the external driver modification and have chosen
not to do it owing to the mods required to the TU's... at least at this
time. I know for a fact a rather simple xtal control mod was done to
these rigs for CAP. Our Wing had a number of the BC-191s and they
worked OK into the early 60's. Unfortunately, those who would have been
privy to the technical aspects of this don't appear to recall or aren't
around, anymore. All I can remember is that there was a little Bud Box
attached to the lower left side of the transmitter. There was no ARC-5
or anything else of consequence, outboard except I seem to recall that
this crystal oscillator drove the VT-25 (10) oscillator tube and
something about only one wire/connection associated with feedback in the
TU being disconnected? Does that seem plausible? That's all folks........

Jeep/K3HVG

Pretty fuzzy now, but I did see a couple of commercial fishing vessels with
converted BC-375's (could have been 191's) that were xtal controlled on the
old "AM" marine bands. New data plate on front from some company in Seattle,
Washington. I cannot be sure at all, now, but I always assumed the
commercial modification (I assume FCC approved) was an added 6L6 oscillator
built into the tuning unit, with another control or two and crystal socket
sticking out the front of the tuner box. That was really a long time ago,
and I was pretty green around commercial gear.
Old Chief Lynn, W7LTQ

(my $50 set was in 1949, NOT 1959.... gracious sakes alive)

"Lynn Coffelt" wrote in message
...

"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


My first transmitter was a BC-375-E which I had
modified to work with an external exciter. I used it on AM
with a preamplifier to allow using a dynamic mic instead of
the carbon mic the input stage was designed for. I even had
this thing on sideband using a Barker and Williamson SSB
generator and some self bias for the amplifier stage.
Probaby the only Class-A linear on the air but it worked.
Mostly, I used it for CW where it worked very well.
The exciter was completely home built using an electron
coupled oscillator circuit copied from a General Radio
frequency meter. Given a reasonable warmup it was very
stable.
I still have this rig in storage but its too large for
my current situation.


--
---
Richard Knoppow
Los Angeles, CA, USA

"Richard Knoppow" wrote in message
...

"Lynn Coffelt" wrote in message
...

"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


My first transmitter was a BC-375-E which I had
modified to work with an external exciter. I used it on AM
with a preamplifier to allow using a dynamic mic instead of
the carbon mic the input stage was designed for. I even had
this thing on sideband using a Barker and Williamson SSB
generator and some self bias for the amplifier stage.
Probaby the only Class-A linear on the air but it worked.
Mostly, I used it for CW where it worked very well.
The exciter was completely home built using an electron
coupled oscillator circuit copied from a General Radio
frequency meter. Given a reasonable warmup it was very
stable.
I still have this rig in storage but its too large for
my current situation.


--
---
Richard Knoppow
Los Angeles, CA, USA


SALUTE, Richard!
You really took that great rig for a ride! Mine was also a BC-375E, I
did try the T-17 microphone once with a guy using a NBFM adapter, and he
reported me working just as well on AM as NBFM! (or maybe phase modulation?
who could tell the difference?) CW was best, especially when one could get
the antenna to load where you could hardly find the plate "dip" anymore, and
looong dashes caused the graphite plate to glow a little red! Wow!

Old Chief Lynn, W7LTQ

At least two BC-191/375s made it into the movies....

In the classic John Wayne "Island In The Sky", it's the main
transmitter in a transport plane downed in the snowy reaches of
northern Canada during WW2. You also see a BC-348 and a Gibson Girl in
action.

In the original "Manchurian Candidate", during the climactic scenes
where Laurence Harvey goes to the unused spotlight room during the
convention, there's a BC-191/375 used as a prop in the room. No
connection to the story at all. The set dresser probably thought it
looked enough like PA equipment to pass muster.

--

The original "Flight of the Phoenix" shows an ART-13 but it is not
used in the story.

73 de Jim, N2EY