[Milsurplus] Re: [ARC5] SCR-274-N Transmitter Dial Accuracy

[Michael Tauson]

On Sat, Jul 5, 2008 at 5:31 AM, Mike Morrow <kk5f at earthlink.net> wrote:

> I've come across several SCR-274-N transmitters with that legend in
> yellow impressed on the tuning dial.

Since I've been out of the collecting game for a while, I don't
remember seeing it before.  All of my previous equipment and manuals
went to the Smithsonian in 1985.

> I have the same opinion that Dave Stinson just expressed, that these
> specs were somewhat arbitrary and of "no never mind" in real use.

This is bad.  We agree on something.

> I have often wondered how the users of the MF/HF commands sets
> netted the receiver to the associated transmitter,

During tuning, they would likely use an LM or BC-221 as John suggested
with the final netting to the bossman during runup as Neil suggested.
Since the aircraft's own transmitters and receivers would have been
tuned to each other by the techs on the ground, the presumption can be
made that their equipment would be pretty close to begin with.

> I doubt that any other contractor produced the extremely broad diversity of output in
> such gigantic quantity.

They had help.  Colonial comes to mind.

> Certainly WE was without any doubt a far far more important contributor to the war effort
> than our favorite A.R.C. was or could ever have been.

I'm trying hard to think of a case of an airplane that flew during the
war that had WE equipment in it but no A.R.C. equipment.  Bendix maybe
with their SCR-522 but no instances of WE come to mind.

The AAF rejected the BC-942 & BC-950 in favor of keeping the SCR-522,
in part because it worked anywhere in the 100-156 MCs range on all
channels, something the WE transmitters failed to do.  The Navy picked
it up then A.R.C. did some redesign so it would work with the ARC-5
system and handed it back over to WE to build, even with the channel
frequency limitations.  This was later addressed with the variation on
a theme called the T-126.

The T-23 was an improvement over the very limited ARC-4 but, like the
ARC-4 and the SCR-522, suffered from channel deficiency.  That problem
begat the Collins ARC-1 for the Navy and Sylvania(?) ARC-3 for the AAF
which increased the channel count to 10 and 8 respectively.

As to the ARR-2 ... I keep associating that with RCA for some reason
even though I know better.

> lives of the beacon band receivers.  They produced the ultimate MF/HF
> command set just at a time when the sun was setting on MF/HF use for
> "command" communications.

Well, "sunset" was delayed a bit longer than one might think.  The
ARC-2, ARC-39 and HF elements (plus the T-23) of the ARC-5 sets
continued in service into the 1960s for local air-air and air-ground
communications.  They didn't have the power to handle liaison work
(10w out vs 100+w out) but they certainly had enough to communicate
locally including the ground elements shoujld there be some need to do
so.  In the mixed ARC-5/Type 12 system I'm assembling, the T-19/R-26
pair is being set up for 3105 KCs which seems as good a frequency to
use as any other.

On the other talon, the R-23A was, as you noted, in service for quite
a while - into the 70s at least.  Not bad for a receiver originally
conceived in 1935.

Oh, yeah.  The original A.R.C. Command Sets were the SCR-183 & GF/RU.
The Type K equipment replaced them even though the earlier Model D
based equipment served well into WW II.

BEst regards,

Michael, WH7HG