[Milsurplus] Navy ATD transmitter

[Meir WF2U]

I actually have an ATD/ARB/LM-20 setup in operation, with the original ATD
dynamotor, remote indicator and the dual ARB control box. The ARB is
completely stock, as issued, so the whole setup is running off 28 VDC. The
two tuning units covering 80 M are on 3570 and 3885 kHz (the CW and the AM
frequencies of the East-Coast "Old Military Radio Net"; the tuning unit
which covers 160 M is on the 160 M AM calling frequency.

The ATD is the heaviest 40 W output transmitter I ever used.. 

Actually, my ATD came with some "hammifications" which didn't make any
sense. It put out a whopping 2 Watts when I powered it up initially, with
the "modifications". Then I restored it to original condition (Mike Hanz
fabricated the antenna terminals for me because the transmitter had a UHF
and a BNC type connector installed). 

On AM I get good audio reports on it and on CW there is only a trace of
chirp.

 

73, Meir WF2U

Landrum, SC

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From: milsurplus-bounces at mailman.qth.net
[mailto:milsurplus-bounces at mailman.qth.net] On Behalf Of Mike Morrow
Sent: Monday, May 02, 2011 1:23 PM
To: milsurplus at mailman.qth.net
Subject: Re: [Milsurplus] Navy ATD transmitter

 

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
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