[Milsurplus] Navy ATD transmitter

[Mike Morrow]

I believe that the ARB was the only receiver designated for use in those few
instances where an ATD to be used.  The list of aircraft vs. radio gear in
the USN document that Mike Hanz has at

 http://aafradio.org/docs/1943-Navy-radio-gear.html 

has three examples for the ATD.  The ARB is specified in each.

The ATD was designed with the ability for pilot control of its four channels.
To accompany that, a receiver with pilot control capability would be required.
Not only does the ARB provide that, it also covers precisely the frequency of
operation provided by the standard ATD.  (I doubt many of the very rare
CRR-47211 9050 to 15800 kHz ATD tuning units were ever made.)

Unlike the ARB, the liaison-service RU-19 and RAX-1 have no pilot control
capability.  Use of these receivers would require using the ATD in strictly
a liaison service role with a non-pilot operator.

In an unrelated area, the standard stuff issued in an ATD set included the
CRR-47206 LF/MF antenna coil (200 to 540 kHz) but *not* the actual transmitter
tuning unit CRR-47207 for that range.  Instead, the CRR-47208 (540 to 1500 kHz)
tuning unit was standard.  That would seem another indication that the USN
thought that having communication capability in that range of frequencies was
of some value.  USN receivers, including the ARB, almost never omitted broadcast
band coverage.  Army Signal Corps receivers almost never included BCB coverage.

I've accumulated a set of the following NOS items that I would like someday
configure together:
(1) ARB, with accessories.
(2) ATD, with accessories including 200 to 540 kHz transmitter tuning unit.
(3) ZB-3,  The ARB comes with mounts for the ZB, and requires no ZB control
           box or ZB antenna switching relay.
(4) LM-20, A CFI is mandatory for a set like this, unlike a set that uses the
           ATC which could be precisely set at 5 or 10 kHz intervals without
           an external CFI.

The RCA ARB and the Bendix ATD are closely matched in coverage, capability, and
technology.  But when matched with the Collins ATC, the ARB was clearly far from
the same level of advanced technology and engineering.  The ATD was a white
elephant after the ATC was available.  Actual flying ATDs must have been very rare,
which is why today ATDs are usually NOS.  Perhaps so many have survived the ham
hack threat because it never was very attractive for ham use.

Mike / KK5F