[Milsurplus] Opinions on ARR-7, APR and other aircraft receivers

[Ray Fantini]

I wasted a little time researching the B-36, may have lamented before about my wanting an ARC-21 and how the earliest versions still carried ARC-8 systems before replacement with the ARC-21 and then ARC-65 and will propose that the B-36 is the best argument for the superiority of the APR-4 Typical group 1 ECM packages included an APR-4, APT-4 radar transmitter and modulator along with a APA-38 panoramic adapter. The group 2 ECM package was an APR-4 receiver, ARQ-8, APT-5, APT-1 radar transmitters and an APA-38 panoramic adapter. A 1953 pre phase two RB-36 had four Ferret ECM(FECM) positions, a low frequency position (38 to 300 MHz )  with one ARR-5 and two APR-4 receivers, a intermediate frequency position (300 to 1000 MHz) with one APR-4 and one ARR-8, a medium frequency position (1 to 4 GHz) with one APR-9 and the high frequency position (4 to 11 GHz) with a APR-9 so its not uncommon for a mid fifties RB-36F to have at least three APR-4 receivers on board. Because of the issues involved with transmission line length the APR-9 receivers would be located in un- pressurized parts of the ship, but the APR-4 operating at lower frequencies were always in the pressurized part of the ship so no heavy gloves required! 
 Magnesium Overcast, chapter 7, pages 153 to 160 has many pictures, charts and lots of information on electronic countermeasures along with pictures of phase one and two ECM packages and layouts of the four Ferret ECM stations.
With all due respect to you I will stand by my assertion that the APR-4 may be one of the most used and successful aircraft receivers of its time, possibly only surpassed by the BC-348, or maybe the APR-9, then again maybe the ARN-6 and 7 get in there too.
RF 


________________________________________
From: milsurplus-bounces at mailman.qth.net [milsurplus-bounces at mailman.qth.net] On Behalf Of Mike Hanz [aaf-radio-1 at aafradio.org]
Sent: Tuesday, August 28, 2012 4:57 PM
To: Milsurplus at mailman.QTH.net
Subject: Re: [Milsurplus] Opinions on ARR-7

On 8/28/2012 9:57 AM, Ray Fantini wrote:

> With all this discussion of counter measurements receivers I would propose that the Hallicrafters designed receivers were a product line that although they filled a need was a product line that went nowhere.

Many people aren't aware that Hallicrafters was actually an important
ECM development company through the late 1960s.  It later became part of
Northrup.  The AN/ARR-5 was a workhorse that is listed in the standard
equipment compliment for the RB-36 in 1953. So, I'm not sure one could
say that the product line went nowhere. It, like every other product
line, underwent evolution with technology and threat.  The ARR-7AX was a
miniature tube version of the classic SX-28 and persisted in USAF
aircraft through the early 1950s.

>   The entire ARR family was obsolete and surplus by the end of the war and the future was the APR-4 series of receivers.

Well,  I have ARR-* listings through AN/ARR-23 listed as of September
1945, and the list was still growing.  You have to remember that the
technology was all about the threat, and the APR-4 only (belatedly) ran
through 2.2 GHz.  By the close of the Korean war, the threats weren't
your father's Oldsmobile any more.  The APR-4 was insensitive and clunky
to use even with the four band tuning unit.  It produces images like you
wouldn't believe except for the lowest freq TU, which had the advantage
of a normal receiver front end with adequate stage filtering.  The APR-4
usage in US aircraft petered out of common use in the mid 1950s with the
AN/APR-4Y, though it spent a lot of time in foreign countries after
that.  Ya gotta remember that we began flying ferret missions at 60,000
feet by then, and it's pretty hard to tune those beasts with pressurized
gloves on.

> Think the APR-4 and APR-1 was introduced around the same time as the Hallicrafters stuff and although the APR will not cover the low frequencies that the ARR-7 did all the ARR stuff disappeared after the war but the APR-4 went on well into the cold war and the APR-4Y was in service into the late sixties and early seventies. Although not popular with the Ham community due to the relatively low sensitivity and wide bandwidth I would propose that the APR-4 series of receivers may be one of the longest used and best counter measure receivers built. And was the choice receiver until replaced by the early Watkins Johnson/ CEI equipment in the sixties. But this is all just speculation on my part.

I guess I have a slightly different take on the technology, but others
certainly may have different views.  I always considered the *real* long
lasting countermeasures receiver to be the AN/APR-9 series, which began
life as an airborne receiver component of the WWII "Elephant" jamming
prototype.  It had receiver heads that went down into the upper HF
region, and with the APA-69 and ALR-8 add-ons, were a part of a complete
panadapter/pulse analysis system that covered up to 10.750GHz.  In
Alfred Price's Volume 2 of "The History of Electronic Warfare" is
recorded this information:  "The APR-9 was destined to be built in
greater numbers, serve longer, and would spawn more developments than
any other item of equipment in the history of electronic warfare...It
would fly its first operational mission in 1947, and more than four
decades later the equipment remains in service in several countries..."
Its basic architecture was used for many years through countless
follow-ons improvements.

Take a look at the innards of an APR-9 receiver some time.  With the
complex servo cam driven tuning mechanism, it makes an APR-4 look like
Og the Caveman made it...:-)   There are a couple of photos of the
system at http://aafradio.org/countermeasures/APR-9.html  Note the CBY
manufacturer (Aircraft Radio Corporation) on the labels...heh, heh...
Not your average AN/ARC-5...

73,
Mike