[Milsurplus] Re: GP-x Transmitter, RAX Rcvr? + TU Wanted

[Mike Morrow]

Dave wrote:

>I should know better than to call an ATC an "ART-13," 
>Mike.  That's like calling an ATA and "ARC-5."

Hi Dave, I wasn't quibbling over that distinction.  After all, many ATC transmitters appear to have been simply re-marked, often just in paint stencils, as T-47/ART-13 units.  But not all T-47 units were originally ATC units.  I have one such T-47.

The real point was that an authentic WWII AN/ARC-8 installation should use the improved T-47A, not the T-47 or ATC.  Then, many old USN ATC and T-47 units were re-worked into USAF AN/ART-13B units.  To make an AN/ART-13B, the USAF used either original USAAF T-47A units, or USN ATC or T-47 units upgraded to a T-47A.  Early AN/ART-13B units had just a CDA-T (the transmitter remained a T-47A), but later units had a CDA-T plus extended MF range switch (the transmitter then became a T-412/ART-13B).

>Mike Hanz has photo documentation of an ATC installed with RAX 
>in a squadron of PB-4Y patrol bombers.

Yes, I've seen those interesting photos.  I'd rather have a BC-348, were I the radio operator.

>Very late war, to be sure...

I would guess just after the ATC arrived in what, 1943 maybe?

>pb4ylias.jpg clearly shows the nomen tag of the ATC
>and the RAX receivers at the Radio Op desk.

There seems to have been a fair number of PB4Y aircraft delivered to the USN with the same radio gear that Consolidated placed in the USAAF equivalent B-24.  AT least, a good number of original B-24s were delivered to the USN and re-designated as PB4Y.  Had I been a USN aviation radioman, that's the aircraft I'd have liked.  The USAAF AN/ARC-8 was so much better than all that oddball dinosaur goofy gear (especially those Westinghouse antiques) that the USN was putting in their aircraft. 

I think the ARA/ATA, ATC, and the ZB/YG homing system are the highlights of the USN's WWII radio innovation.  Just about all else was significantly dated, awkwardly large, and/or bizarre.  (I can disparage the USN with little guilt, having been Regular US Navy myself.)  The USAAF improved the ATC for their AN/ARC-8, which included the best WWII match for the T-47A, the grand little BC-348.  The USAAF developed a pretty clever auto-tuning VHF-AM set called the AN/ARC-3, and ADF systems like the SCR-269 and AN/ARN-7 that put to shame any USN RDF (Even the USN often used the SCR-269).  All these USAAF sets had long post-war service life. 

The USN was finally reaching its stride at the very end of the war with wonderful modern sets like the VHF AN/ARC-1 (and the related UHF AN/ARC-12), HF AN/ARC-2, and the HF AN/ARR-15 (even though the AN/ARR-15 lacked the 0.2 to 0.55 mc coverage that it should had had).

>I include pby4comm.jpg because it shows the Command 
>Set included the ATB/ARB, with I think is the coolest-looking 
>WWII Command rig, even if it was scarce.

The ATB components, especially the mounting rails, seem to have disappeared to Neptune.  I've only been able to locate an ATB and the metering unit.  I don't care that much for the design.  I'd have expected the ATB and ARB to have at least hade the same shape and form factor, but they are very different.  What was RCA thinking?

IMO, the very late WWII AN/ARC-2 was the coolest HF set of WWII, after the AN/ARC-8.  The AN/ARC-2 seems to have served for both command and liason roles, apparently with limited success.  But some were still flying into the mid-1970s on TS-2A training aircraft at NAS Corpus Christi.  The aviation electronics techs I talked to back then said that getting new parts was problematic.

>I have all three of the tuning units...but have not
>yet done the work to determine which goes with what set.

As a *general* guideline, the USN used the small CU-25 0.2 to 0.6 mc and the CU-26 0.5 to 1.5 mc external tank coils to provide for optional LF/MF coverage in the 0.2 to 1.5 mc range of the O-16/ART-13.  The LF/MF antenna connects to the CU-25 or -26, then the CU-25 or -26 connects to the "loading coil" terminal on the transmittter.  As a consequence, the LF/MF antenna is used ONLY on transmit.  The receiver continues to use the MF/HF antenna.  To get around this limitation, the USAAF developed the optional SA-22/ART-13A antenna switching unit to provide relay-activated antenna switching which allows both the transmitter and the receiver to use the same LF/MF antenna.

The USAF later developed the gigantic LF/MF tank coil and antenna switching unit called the CU-32/ART-13A.  It is something close to being a CU-25 and SA-22 in one (big) box, plus a bogus "RF amps" meter (that doesn't really measure antenna amps!).  The CU-32 provides full functionality with the optional O-17/ART-13A, covering 0.2 to 0.6 mc.

>Is there a nomenclature for the set in the PB4-Ys
>with the ATC and RAXs?  I might decide to do that one
>rather than the AN/ARC-8, just because it was less common.

That would be challenging combo to do right.  It is surprisingly difficult to put together a complete RAX-series.  I have only the RAX-1 CG-46115 receiver with all the correct stuff like the rack mount and dynamotor.  My other RAX-1 units are close to being just ham-molested junk.  Late RAX-1 units have plastic tuning and gain contol knobs, which is off-putting!  Technology-wise, the RAX seems to me to be more matching to a GO, therefore mixing GE and Westinghouse sets!

One of the other big challenges for the ATC installation that is shown in the ATC/RAX-1 photos on Mike's site is the ATC mounting system.  It is using the ATC equivalent of the early rail mounting system that had no shock mounts, similar to the mounting rails found on the GP and the ATD transmitters.  In the JAN system, this was known as the MT-161/ART-13, and it was replaced by the MT-283 and MT-284/ART-13 shock mount system.  I think the USAAF was also responsible for that improvement, but it appears that the USN also adopted the new mount in short order.  I've only seen one ATC with the original MT-161 mount, at Dayton about ten years ago.  I thought about buying it for that reason alone, but didn't.

>That would mean duplicating the RU set...  ah, well.

Save the RU for the GF, GP, and GP!

73,
Mike / KK5F