[Milsurplus] airborne radio activity

[David Stinson]

Marty R's GI-stuff haunt wrote:
> 
> Yo ARC5 Dave
> 
> Let me excerpt from
> 
>   US Army in WW2 - Sig. Corps, The Outcome, P. 501
> 
>   ...that by 1943 the old high frequency aircraft radio SCR-274 had yielded
>      to the VHF SCR-522 which leaped up to the 100 to 156 megacycle
>      range...


This is a good example of how one must be careful with "history."
From this excerpt it would be easy to assume that all 
SCR-274Ns had been scrapped to Radio Row by 1943.
This is conclusively not the case;
the system continued in use long after that.
The two systems were not mutually exclusive.
Both were often installed in the same aircraft. 
They served different functions dependent upon 
the particular mission needs.  And we must give 
weight to the surviving documents as primary sources.
For example- the B-24 erection manuals dated April of
1943 specify SCR-274N as the command radio.
Later bomber documents show the
installation of SCR-522, but only in addition to 
the already existing SCR-274N. 
Any system in a bomber required time, parts and attention
to maintain.  Were the 274N "obsolete," it would have been 
removed and the 522 installed in its place.  
But this did not happen in bombers.  
The 522 was added on because the added capability was needed.

In a posting I did a couple of months ago, I documented 
that VHF was primary on the northeastern seaboard of the U.S.,
in *southern* Britain, the front lines and conquered areas of the ETO.
You still had to have pilot-accessable HF just about everywhere else,
including many civilian airfields in those areas 
and the Army Airways stations along the way.

In tactical aircraft assigned to western Europe, 
coordination with the Brits was important and space was limited.  
The 522 was the logical choice.
An western ETO P-47 might fly from an airfield in Normandy
to the front and back.  VHF would keep him in touch 
all the way, so SCR-522 was best.  However- if you were
going to move a flight of P-47s from North Africa to Sicily 
or southern Italy, or go on U-boat patrols in the Caribbean,
pilot accessible HF would have been absolutely vital.

Even in the western ETO, VHF was not at all universal early on.
Most of the British aircraft that fought the Battle of Britain
did so with the old, crystal controlled HF TR-9.
It took American mass production to get the 522 in most 
aircraft and this did not magically happen overnight.
 
> Hey on REPEATERS.  PLEASE note the twin SCR-522 set-up (later called
> ARC-10 ala WB5CAB) was a RELAY not a repeater.  You set your 522 to
> receive & transmit on ONE freq & the "over channel relay" would send &
> receive on another freq. 'way removed. 
> Half duplex, one channel button for the circuit.
I sure would like to see a manual on this.  I'd especially
like to see how they did the carrier operated relay to do 
the PTT on the transmitting set.  Does anyone have one of these books??

> By the way your "radio horizon" stuff is well taken, well done.  It
> flys in the face of my pal's saying "we were VHF to England (in 3/45)
> all the way to Berlin."
Well, I don't think he's intentionally fabricating anything.
60 year old memories are misty, smoky things.  Perhaps 
they were talking to forward tactical VHF stations and
they in turned relayed to the rear, but I'd think such a 
system would have been unreliable for liaison work.
The tactical system operators were not trained to 
handle that kind of traffic.
Bombers certainly did use the 522 to talk to their fighter escort
and to the escort controllers.  The 274N would have talked to 
fighters in, say, late 1942.  Then after the 522 became widely
installed the bombers would have installed one, at least in 
their lead ships.  Later they all would have wanted one and 
likely got them by late 1944 or early 1945.
 
> AAF loved "rolling their own." An example is procurement of scads of
> Jefferson-Travis JT-350s for HF installs in radar-service small-trucks.
> Field expedients!  Neat!!!

Yes indeed.  You give a great example of why you can 
"never say never" and "never say always" about this stuff.
Someone out there was using his head and cobbling up 
whatever worked with whatever he could get.
For example- I have photos of SCR-274N and AN/ARC-6 (not 5)
both being used as Air Traffic Control stations in forward
airfields.  And the SCR-522 was cobbled for ground use
long before the "official" ground version came out.

73 DE Dave AB5S