[ARC5] R23 repair, dynamotor mounts, questions...AN/ARN-9

[Mike Morrow]

>> I grew up with the ARN-14/ARN-18 and the ID-249.  
>> They were around for a very long time!!!

Not "were" around...the system is still in universal service.  The sets you mention are only improved versions of the USAAF SCS-51 ILS, which by end of WWII used the six-channel RC-103 VHF localizer (BC-733-*) and the three-channel R-89/ARN-5 UHF glide slope, both going to the I-101-* cross-needle indicstor.  That 70-year-old gear would work as well today at a modern airport as long as the airport's ILS transmitters are on one of the few available on the old BC-733-* and R-89.

Description of the Air-Track ILS may be found by google-ing "Air-Track landing system".  Attached is a 1939 ad by the Air-Track company.

The USN implemented the airborne part of this ILS with the ZA, ZA-1, ZAX, and AN/ARN-9 equipment.  The ground portion was the YB (and -1, -2, -3), which consisted of
YC localizer transmitter (300 to 800 kHz),
YC glide-slope transmitter (90 to 95 MHz),
YD marker-beacon transmitter (300 to 800 kHz).

The YD was always the same frequency as the localizer YC, and was tone modulated to indicate aurally to the pilot that he was over the start of the runway and doud begin his final descent to the runway.  Because there could be  multiple runways or a need to approach from the opposite end of the runway, the YD was portable in a motorcycle sidecar or jeep so the very important marker beacon could be positioned at the start of the runway.  Somewhat awkward system!

The YB (YC, YD) could also be used at sea with the YD positioned permanently.

So is that weird or what?  :-)

Mike / KK5F