[ARC5] SCR-183 / SCR-283 Info

[arc5 at ix.netcom.com]

The SCR-183 (12 volt, BC-230 transmitter) and
SCR-283  (28 volt, BC-430 transmitter) don't get nearly the
respect and interest they deserve.   They saw service from 1932 
until well after WWII, and longer service than that in smaller-
nation air forces.  They are an excellent design
* for the mission for which they were intended. *
They got some bad press because they got deployed 
inappropriately in some high-profile cases.
They are lower-power than the SCR-274N and ARC-5
and were less available in the surplus market, so most
of them have gone to grief by now.  
That's too bad, because it's a cool set.  

The Army and Navy sets were identical, at first.
The design originated with Aircraft Radio Corporation
in 1932 with the Navy "GF" (at the time, GF was the 
designation for the complete set including receiver.  
"RU" was the receiver alone.  
The designation changed to "GF" being just
the transmitter with the next itteration, GF-1).

The Army copied the 1932 design nut-for-bolt under 
Order Number SC. 132311, June 1932
 and designated it SCR-AA-183.  
That's right, folks: SCR-274N was not 
the first time the Signal Corps copied 
a design A.R.C. had done for the Navy. 
This early design suffered from problems with the
plug-in tuning unit coil tapping mechanism, 
and with tube quality issues.
In 1934, the Navy had A.R.C. completely overhaul
the design of the GF transmitter and produce the 
GF-2, which is the higher-power P-P 837 transmitter 
with which we are familiar.
The Army, having far less money to throw around
(they don't call it "spending like a drunken sailor"
for nothing),  incorporated the mostly mechanical
improvements between GF and GF-1, 
built some false-starts like transmitter BC-AA-200,
but eventually nudged the design to June 1935's SCR-AE-183
and the set stayed basicly the same until the last production runs
(-AR and -AS) in the first year of the war.

Things get very muddy between -AA and -AF.
A.R.C. made the 1932 -AA, based on the GF,
then handed it off to Western Electric and Graybar
in 1934, which then became the -AB.  Weco built 
the -AD in June of 1934 and the -AF in July of 1935, 
and all were basically the 1932 design from the old GF, 
bad coil tap contacts and all.
In the middle of this, in June of 1935, A.R.C. produced the
mechanically improved -AE model, which went on- with
minor differences- to be  the standard design 
to the end of production.  
But that's all another (long) story.

Mike Hanz has been exceedingly kind and generous 
with time and help on the SCR-283 set I'm building.
Here's an "intermediate" stage:

http://home.netcom.com/~arc5/SCR-AH-183/183a.JPG

and the latest improvements:

http://home.netcom.com/~arc5/SCR-AH-183/183STEEL.JPG

The dynamotor is a later, unpainted version.
I'm considering remounting and compacting the set.

On to your transmitter.  
You'll need a proper tuning unit.  Please send a photo
of the nomenclature plate of the unit you have, since 
there's just a chance it's an early one that will work.
Here is the diagram and notes for connecting your transmitter.
Your BC-430 is the 24-volt version, and only the 
tube fil wiring will be different: 

http://home.netcom.com/~arc5/SCR-AH-183/BC230TX.JPG

Parts lists are at:

http://home.netcom.com/~arc5/SCR-AH-183/230PAR1.JPG

and

http://home.netcom.com/~arc5/SCR-AH-183/230PAR2.JPG

Tubes:  The original tubes have become little golden gods to 
the audiophools, but don't give up.  Many tubes will work 
fine in this circuit.  I've wired 6AQ5s as triodes (screen to plate)
and mounted them in old four-pin sockets.  They neutralize and
tune-up just like the expensive tubes.  The set will put out a
mighty 3-4 watts carrier.  Don't laugh; I've been working 
100-200 mile AM contacts on our local nets with it.
With proper tuning and a good power supply, the rig is surprisingly
stable though, as with any MOPA rig, there will be a certain
amount of "chirp" on CW.  Not bad on mine.

If you're interested in going further, I can give you a lot more info.

Right now, gotta get the kids to bed. :)

73 OM DE Dave AB5S

p.s. Here's another project that's proceeding apace 
with Mike's kind help:  My Navy ATB / ARB, 
which is on the air making contacts:

http://home.netcom.com/~arc5/ATBARB.JPG