[ARC5] The AN/APS-13 In Three Different Combat Roles

[Geoff]

When in NY I converted a pair of the ($2 with tubes NIB at Radio Row) 
APS-13's to 420mc transceivers in the late 50's to talk to a friend (and his 
sister a bit later and more often) 4 blocks away. Never did know what 
frequency they were on and just tuned for best 2 way performance.

Later when I was living in MA in the early 60's I used them as a DX chasing 
alert link with a friend about a mile away. I wound up dating his daughter 
also who I still stay in touch with strictly as friends. When I moved to NH 
in 67 they couldnt make the 12 mile trip so a pair of APX-6's were converted 
and they did very well with 32el HB collinears at both ends. No idea what 
frequency they were on either, somewhere around 1215-1250 mc was the goal.

Carl



----- Original Message ----- 
From: "Mike Morrow" <kk5f at earthlink.net>
To: <milsurplus at mailman.qth.net>; <arc5 at mailman.qth.net>
Sent: Monday, January 07, 2013 3:57 PM
Subject: [ARC5] The AN/APS-13 In Three Different Combat Roles


>> When I visited the Hiroshima Memorial museum in Japan, I saw a
>> cylindrical transmitter ( about the size of a quart of milk)that stated
>> was used to trigger "Fat Boy". It appeared to be a vhf transmitter with
>> either a 4-65A or 3x-250 in the final.
>
> That bears no similarity at all to the four units that were used.
>
> It has already been pointed out that four AN/APS-13 units (RT-34/APS-13,
> made by both RCA and GE) were used in the altitude radar triggering 
> system.
> The stock RT-34 operates around 450 MHz, 450 watts peak pulsed, from two 
> small
> 6J6 tubes.  These four sets used in the triggering system had to be 
> altered
> in frequency of operation to prevent mutual interference.  The small 
> antennas
> seen on the bombs are AS-62/APS-13 units.
>
> Here is a description of its use in the bomb trigger system:
>
>  http://cryptome.org/nuke-fuze.htm
>
>> Does this bear any relation to the Buzzbomb one?
>
> No.  The AN/ART-19 is an HF RDF tracking device only.  The AN/APS-13 as 
> deployed
> on the weapons was a pulsed radar that triggered the weapon at about 1900
> feet above ground.  Even modern nuclear weapon re-entry vehicles use a 
> small
> altitude trigger radar.
>
>> Would be interesting to see a diagram of it.
>
> The schematic of the RT-34/APS-13 can be found at:
>
>  http://www.nj7p.org/millist/sch/rt-34.gif
>
> A few more details are at:
>
>  http://www.nj7p.org/cgi-bin/millist2?mode=normal&name=AN/APS-13
>
> A very nice description of the AN/APS-13, with operating manual extracts
> and photos, is at:
>
>  http://www.duxfordradiosociety.org/restoration/equip/aps13/aps13.html
>
> This system, designed to trigger a bell and alarm light in the cockpit
> if a large metal object was detected behind the aircraft, was short-lived
> in WWII service on night fighters like the P-51 and P-61.  It was found
> by the British that its emission could be used by German aircraft with the
> FuG-227 radar detector system to locate any aircraft using the AN/APS-13.
>
> The UK later re-deployed the system, but now configured to detect objects
> in *front* of fighter aircraft, to aid their location of the Fi-103 (V-1)
> targets:
>
>  http://www.hawkertempest.se/ElectronicWar.htm
>
> Anyone familiar with the 1950s-era military radio surplus scene will 
> recall
> that thousands of these were available surplus after WWII for dirt-cheap
> prices (about $1 less tubes).  It is a small unit with a a small built-in
> dynamotor...all similar to but smaller than the RT-7/APN-1 radar 
> altimeter.
> The last one I've bought actually did cost $1 27 years ago...but was in 
> new
> condition, with all tubes.  The advertisements in the ham magazines called
> them "Tail-end Charlies".  I've always considered it an interesting set.
>
> I doubt that there was very much to salvage from the eight AN/APS-13 sets
> that were on those two atom weapons.  :-)
>
> Mike / KK5F
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