[Milsurplus] ZA Receiver/Indicator

[Mike Morrow]

Robert wrote:

>I have the Instruction Book available.  Like most radio and radio related 
>instruction books, it says nothing about specific installations (type of 
>aircraft).

The ZA is the USN's version of the pre-WWII commercial Air-Track ILS.  The ZA manual specifies its use with various models of the RU as the localizer receiver.  You have the glide path receiver.

I've owned a couple of pieces of the ZA system.  Both items had the aircraft type indicated in white paint or ink lightly stamped on the case.  My receiver unit has PBY-5A on it and, IIRC, the impedance adapter had PBM on it.  That agrees with Jack's statement about patrol aircraft usage of the ZA or ZA-1.  Take a closer look at the case of your item for a such a marking, and let us know what you find.

The Air-Track Company developed an improved ZAX system that became the AN/ARN-9, but all use of Air-Track systems seems to have been dropped by mid-war.   The Air-Track ILS was tricky, uncertain, complex and awkward to use.  Better than nothing, I guess.

Mike Hanz has some wonderful photos of the electronics installed in a 1944 PB4Y-2:
  
http://aafradio.org/sidebar/PB4Y2_Line_Maintenance_Manual.html

The picture of the R-23/ARC-5 found there shows an unconnected MX-19/ARC-5 Air-Track ILS adapter installed that should have connected the R-23 as the localizer receiver to an Air-Track ILS (the AN/ARN-9 version).  It not being connected, and no AN/ARN-9 components being shown, would seem to indicate that the Air-Track system had been dropped before 1944.

The technology of the Army Signal Corps' excellent, easy-to-use, but very different SCS-51 ILS system (RC-103 localizer and AN/ARN-5 glide slope) became the standard that remains in worldwide civil and military use today.

Mike / KK5F
PS:  I'm seeking any AN/ARN-9 info that others may wish to share.  Not much is out there.