[Milsurplus] [ARC5] Opinions on ARR-7. (Excerpt From Secret WWII Publication)

[Mike Hanz]

On 8/27/2012 10:12 PM, Mike Morrow wrote:
> >From "Graphic Survey of Radio and Radar Equipment Used By the Army Air Forces,
> Section One, Countermeasures Equipment", dated 1 February 1945 (SECRET):
>
> "RADIO RECEIVING SET AN/ARR-7
>
> "Radio Receiving Set AN/ARR-7 is an airborne intercept receiver covering
> the frequency band 550 kc. to 28 mc.  The set has been adapted from a
> Hallicrafters SX-28 receiver omitting the band switching units used in
> the commercial receiver for reception above 28 mc....
> ...Power is obtained from Rectifier Power Unit PP-33/AR
> for 110 volt, 60 c.p.s. operation or from PP-32/AR for 85-100 volt, 400 to
> 2600 c.p.s. operation.
>   
> "...It operates on AM, FM
> and CW..."
>   
> Notice that the mythological PP-33/AR 60 c.p.s. power unit is mentioned
> in the description.  I suspect it never saw deployment...the publication's
> description for the companion AN/ARR-5 mentions only the PP-32/AR.

Great catch, Mike!  I did briefly look at that yesterday, but missed the 
PP-33/AR designation...I think partly influenced by its errors - look at 
http://aafradio.org/countermeasures/ARR-7.jpg and see if you can detect 
a presence of the "omitted" 21-42MHz band on the bandswitch. :-) Oh, and 
the claim for FM reception must have assumed slope detection - there 
certainly isn't a switch position for it.  What they may have meant was 
that for frequencies above 28MHz, the ARR-5 is used, and that does 
include an FM capability.
> Mike Hanz wrote:
>> "If you can't hear 'em,
>> you can't jam 'em..." :-)
> One must wonder what transmitter would have been intended for jamming
> anything within the MF/HF spectrum of the AN/ARR-7.  There were jamming
> tuning units for use with the SCR-287-A (BC-375-*) that covered all
> together from 2 to 30 MHz:
>
> There was also a proposed AN/ARA-3(XA-1) jamming modulator for use with
> the SCR-278-A.  I could swear I've heard of a MD-30?/ARA that was actually
> used, bt I can't find any record now.

I started to mention the mod kits for the usual cast of HF aircraft 
transmitters, but my note was already getting a bit long.  I even have a 
schematic here for modifying the little ARC ATA transmitters for jamming 
service...go figure. :-)   They used a CUO 631597 "coupling unit" to tie 
the noise source to the normal modulator in whatever rig was being used 
as a jammer.  In addition, there were nomenclatured jammers that covered 
the ARR-7 range to one degree or another - I posted a listing of them 
from a 1944 Navy pub at http://aafradio.org/docs/Countermeasures.pdf - 
but it does *not* include everything the Army was using at the time.  It 
includes an improbable AN/ART-1, which required 30 *kilowatts* of 440 
volt 60 Hz power in the aircraft.  A bridge too far, perhaps.  I know 
that the flight tests with the prototype of the AN/ARQ-11 in my 
collection required the mounting of *two* Onan engine generators in the 
bomb bay, and it only needed a little over 5 kilowatts of 400Hz power.

> My sentimental favorite airborne jammer is the RT-45/ARQ-1 (14 to 50 MHz).
> I wonder if any were ever actually used.  I like your 2010 response to a
> posting on the Antique Radios forum:

Sheesh.  I need to be more careful.  I didn't think anyone actually ever 
read anything I wrote, let alone remember it for more than a day.  At my 
age, I'm beginning to worry that the time will come when I will 
vociferously disagree with one of my old posts, forgetting that I wrote 
it...:'(

I like the ARQ-1 as well.  It is one of those radio sets that can be 
described as "cute" - http://aafradio.org/countermeasures/ARQ-1.jpg has 
a photo.  I can't ever recall seeing one that wasn't NOS, but I think 
its original purpose was overtaken by events before fielding. A lot of 
that sort of thing was happening in the countermeasures world during the 
war.

> I guess that the JAN "AN/ALx-xx" nomenclature appropriate to all this 
> stuff was not yet in use by the end of WWII.

Correct.  There was a postwar hole in ECM equipment development that 
didn't get plugged until the Korean War caught us without much of a 
capability, thus the feverish return by the military to Radio Row to 
purchase "war surplus" to fill the gap.  The ALA, ALR, and ALT stuff 
didn't start appearing until the 1950s.

73,
Mike  KC4TOS