[ARC5] YG,ZB question or two

[Mike Hanz]

On 7/2/2011 1:53 PM, Mike Morrow wrote:
> I believe that the (YE, YG)/(ZB, AN/ARR-1, AN/ARR-2) homing system has
> been very unfairly relegated to obscurity, most like a result of ignorance.
> It was a monumentally important (and simple and inexpensive) technology
> that seems to have escaped all notice in post-war ham press except by
> knowledgeable people like Gordon White in CQ in the late 1960s and Walt
> Hutchens in ER in the mid-1990s.

   Even more remarkable is that the ZB-* was demonstrated to the bigwigs 
in May of 1938 (using an RU, of course), and swiftly began being 
produced by the end of that year for carrier groups.

> I believe that it is impossible to credibly replicate a *historically*
> accurate RU-*/GF-* without ZB-*, an ARA/ATA set without the CBY-46145
> and ZB-*, an ARB/ATB without ZB-*, or an AN/ARC-5 set without the AN/ARR-2.
> That helps to illustrate how essential this homing system was for USN
> carrier-based (and likely, island-based) operations.

That would make sense to me as well.

> I also suspect that all those DU-*/DW-* LF/MF loops were completely
> valueless as soon as the ZB-* was available (pre-war), both for the
> ARA/ATA and the older RU-*/GF-*.

Certainly for the carrier groups, though for smaller aircraft patrol and 
logistics flights to/from carriers I think the loss of value was more 
gradual - not all island bases had YE/YG transmitters. :-)

> That seems apparent because the design
> of the 1940 ARA eliminated the loop antenna connections from the RAV
> CBY-46102 and -46103 to make the ARA CBY-46129 and -46145.  (The only
> real mystery is why the loop connections returned for the R-23 and
> R-24/ARC-5.)

Well, I'm not completely sure I follow - the DU-*/DW-* loop coupler 
outputs used that strange homemade single ended coax cable shown at the 
end of http://aafradio.org/docs/DU-1.pdf and required only a single post 
design on the receiver.  The dual posts were intended to be used with 
the headrest and fuselage loop antennas, if I read the history 
correctly.  Once they fell out of favor, the terminals were questionable 
- though it certainly doesn't explain the reappearance of the terminals 
in the ARC-5.  Interestingly enough, the installation photo of the 
prototype ZB installed on an RU looks like it utilized a DU "coax" cable 
to get from the ZB to the RU antenna terminal!

> It would be great to have more historical details about how and who
> developed the YE/ZB.

According to the NRL book, the drivers were twofold.  Single seat 
fighters used a fixed loop antenna in the pilot's headrest or wound 
around the fuselage, and taking signal strength readings required a lot 
of slewing around to get directions.  Two (and greater) place aircraft 
had the external loops like the RDF-1 and RDF-2 (and eventually the DZ-* 
and the Bendix products), but they paid a penalty in weight and 
aerodynamics.  The solution to both problems was the ZB/YE-YG system, 
though tube technology didn't permit a transmitter with enough power to 
be built until 1937.  If you believe the book, it seems to have been 
developed within NRL, which certainly made security easier to maintain.  
Interestingly enough, there was a version called the YL-YN built in 1942 
for amphibious landings, but it doesn't record how many of them were used.

73,
Mike