[ARC5] Pilot's control box, CZR-23214...and ZB discussion!

[Mike Morrow]

>...the ZB series of radio equipment comprised the AN / ARR-1,

The ZB-series was the original USN version.  The AN/ARR-1 was the JAN
nomenclature of the later versions, which were essentially the same
as the original ZB but had the tuning dial calibration showing "34" to
"58" rather than the actual "234" to "258" MC.  Tricky!

The USN ZB-series was used primarily with the RU, ARA, and ARB receivers.
USN AN/ARR-1 sets were likely intended for use with the R-24/ARC-5, except
that the whole "homing adapter with BC band receiver" system was replaced
by the R-4/ARR-2 homing receiver which combined both parts into a more
versatile single package that would fit in a command set receiver rack slot.
USAAF AN/ARR-1 sets were intended for use with the BC-946-B in the SCR-274-N,
but I have documentation that shows B-29 aircraft using their AN/ARR-1 with
the AN/ARN-7 ADF receiver.

The homing adapter, the control box such as you have a part, and an antenna
relay are the three major parts of a full ZB-* or AN/ARR-1.  But the control
box and antenna relay were completely unnecessary if the homing adapter was
used with the ARA, ARB, AN/ARC-5, or the SCR-274-N systems.  That's likely
why the homing adapters are so very common, but the control box and antenna
relay are not.

>...essentially a frequency converter from the carrier frequency of around
>230 MHz...

A carrier set between 234 to 258 MHz was modulated by a BC band signal.
The homing adapter demodulated that signal to produce the BC band signal,
which could itself be either keyed CW or modulated AM voice.  Adapter
output was fed to a broadcast band receiver input to present an audio 
signal to the pilot.

>This was part of a very clever system for advising aircraft where their
>aircraft carrier was when they had to return.

There were some AN/ARR-1 systems installed on USAAF aircraft.  Many of
the AN/ARR-1 components have USAAF order numbers on them.  In the Pacific,
the system could have helped find that island on which one was supposed to
land.

There has been some speculation on this list that the USAAF P-38 aircraft
that intercepted IJN Admiral Yamamoto may have been equiped with a ZB or
AN/ARR-1 to help navigate so accurately those hundreds of miles of Pacific
that the P-38s covered.  One pilot's statement said that a special navy
compass was used (which could have referred to a ZB), but there seems to be
little to substantiate.  The P-38 pilots claim to have flown at low altitude
for the mission, so a ZB would not be long useful under those circumstances.

Mike / KK5F