[ARC5] IFF Sets

[Edward Greeley]

Ah, confusion reigns! First, the SCR-717 was an S band surface search 
radar, while the AN/APS-15 was an X band surface search radar of 
slightly later vintage and much better performance from a resolution and 
accuracy standpoint. There would have been no reason for an APS-15 to be 
used as an "add-on" to an SCR-717. Both sets had similar functions: 
airborne ground surveillance and targeting.

As for the AN/APX-15, its  purpose was as described below by Mr. Morrow 
for use with the AN/APQ-13. I'm sure the APX-15 could have been used 
with either the SCR-717 or the APS-15 as well.

The APS-15 was, basically, a repackaged APQ-13 and both sets, I believe, 
were called "H2X" or "Mickey" by the Brits.

As a matter of absolutely no interest to anyone I'm sure, I had a nearly 
complete APS-15, and the MG set to run it, back in the late '60s. I 
planned to use it on my boat. Problem was, it was complete EXCEPT for 
the rotary coupler and feed horn (or was it a dipole feed?) for the dish 
antenna. Never could get hold of suitable "plumbing" for the thing at a 
price I could afford...oh, well, gone but not forgotten.

Ed Greeley


Mike Everette wrote:

> APX-15... are you sure it was not an APS-15?  (Yes, I know the difference between the two designations, in the JAN system.)
> 
> I ask, because among my dad's WW2 radio and radar school notes is a folder on the AN/APS-15A which was an add-on for the SCR-717 system.  I have not looked at this material in a really long time, and it would take some time to find it among my "library," but I recall that this was described as a blind-bombing device.
> 
> This folder consists mostly of hand written class notes, with a few printed sheets.  It's nowhere near as comprehensive as his material for the SCR-717, which takes up the major portion of his radar school manual.
> 
> Dad was trained to work on B-29 equipment and deployed to the CBI in the fall of 1944.  If there was an APX-15 system it would seem logical that he would have been trained on it before leaving the States... maybe, anyway. When the B-29s moved to the Pacific he stayed behind in India to work on AI and IFF gear, much of it on night fighters (both US and British a/c as he was on a joint base), but also installing equipment on B-24s on their way to China.  He apparently ended up with a lot of time on his hands and actually spent a lot of it flying the Hump as a radio operator on C-46s.
> 
> 73
> 
> Mike
> W4DSE
> 
> --- On Sun, 12/23/12, Mike Morrow <kk5f at earthlink.net> wrote:
> 
> 
>>From: Mike Morrow <kk5f at earthlink.net>
>>Subject: [ARC5] IFF Sets
>>To: arc5 at mailman.qth.net
>>Date: Sunday, December 23, 2012, 1:19 PM
>>Jeep wrote:
>>
>>
>>>...the current system for MIL is pretty much the same,
>>
>>with Mode 2/B
>>
>>>being the mil only discreet codes for air defense
>>
>>uses.  The Civil
>>
>>>Mode A (mode 1)  and C (mode 3) are used, with
>>
>>mode C including your
>>
>>>altitude info (via an encoder).
>>
>>Then in the 1960s, the military added Mode 4.  The late
>>Vietnam-era AN/APX-72
>>included Mode 4, but a KIT-1A/TSEC encoding "computer" was
>>required to be
>>attached.  The AN/APX-72 is doubtless flying still
>>today...and swimming as
>>well.  My missile submarine used the AN/APX-72 as its
>>IFF set for (very rare)
>>work with aircraft.  Its fuses were normally pulled to
>>prevent unintended
>>transmission from the unit.  It got the Communications
>>officer on my sub fired
>>when it was determined he had gotten one day ahead of where
>>he should have
>>been in the daily destruction of the coding cards.
>>
>>In my collections, I find the old RT-82/APX-6 to be a far
>>more interesting
>>piece of hardware than the RT-859A/APX-72.  :-)
>>
>>I also have the ABK-* IFF (a.k.a. the SCR-595-A) and the
>>SCR-695-A IFF (a.k.a.
>>the ABF-*).  I'd like to find a complete (with original
>>tubes) AN/APX-2
>>someday, as well as a AN/APX-44.
>>
>>There was an interesting IFF set of a sort designed to add
>>on to the AN/APQ-13
>>bombing radar on B-29s called the AN/APX-15.  It
>>produced a warning display
>>when radar return that was characteristic of the propellars
>>of certain classes
>>of Japanese aircraft was detected.  I don't know if any
>>were ever deployed.
>>
>>Mike / KK5F
>>______________________________________________________________