[ARC5] Original Design Purpose: RAT, RAV, RAX

[Mike Morrow]

Dave wrote:
 
> But again- whatever their original design role, I stand by the use
> of these sets in an ELINT role at some point.  

I wouldn't disagree.  In fact I once thought that the receivers covering
13.5 to 27 MHz had that role as a primary design feature.  But now,
I'm leaning to a conclusion that receivers covering up to 27 MHz were
**originally** designed for liaison service, but their design subsequently
supported some ELINT service.

Robert provided this info from SHIPS 242A:

> All ten GO models covered 300-600 KC.  GO covered 4000-13575 KC (the 4000 
> may be a typo, but as it was the only model made by CHS it may be correct).  
> GO-1 thru GO-3 covered 3000-13575 KC.  GO-4 thru GO-6 covered 3000-26500 KC. 
> GO-7 thru GO-9 covered 3000-18100 KC.
> The receiver listed for GO thru GO-8 is RU Series.
> For GO-9 is RU-18, RU-19 or RAX-1.

I was very surprised that the mid- to late-1930s GO-4 to GO-6 transmitters
were designed with 26.5 MHz as the upper operating range.  I now suspect that
the RAT was **originally** designed to provide coverage above the associated
RU's 13.575 MHz to support the full range of these GOs, i.e., for use as a 
liaison receiver.  This seems supported by the frequency at which coverage
begins in the RAT: 13.5 MHz.  That's almost exactly where RU coverage ends.

The RU receivers that were paired with the GO-series, though locally controlled,
still used receiver control boxes at the operator's position.  Likewise, the RAT
could be locally controlled at the reciever front panel, OR controlled from a
control box/tuning head, presumably still at the operator's position.

It would then be logical that A.R.C. or the USN expanded the RAT design to
the RAV as a system that could replace the RU plus RAT as liaison receivers
covering the full GO transmitting range.  Since all receivers at the
operator's position could now be locally controlled at the receiver's front
panel, NO remote control boxes are provided in the RAV system.

It would also be logical that a competing system covering the same frequency
range as the RAV would be desired for liaison receiver use...hence the far
far more successful GE RAX which covers the same frequency range and is also
designed only for local control.

My point is that, in my ignorance of the existence of production transmitters
for the USN that covered up to 26.5 MC, I had never seen any liaison role
for receivers covering above 13.5 MHz.  Knowing now about the USN's flirtation
with liaison transmitting equipment operating up to 27 MHz, one may reasonably
(if not correctly) explain the existance of RAT, RAV, and RAX receivers with
coverage to 27 MHz as justified on nothing more than a need for such coverage
in liaison set service.  No ELINT purpose need be assumed to explain the existence
of these receivers.

The later GO-7 through -9 transmitters, as well as the ATC and ATD, greatly
reduced the upper frequency of operation.  One might conclude that the attempt
to use frequencies as high as 26.5 MHz was not successful or not worth the
effort for the existing level of technology.  Yet the legacy of the original
need for coverage to 27 MHz for liaison use survived in the RAX and RAX-1 design.

Although the RAT and RAV were failures (judging on the acquisition of only
fifty or less of each) in the original liaison role, at least three of the RAV receivers (CBY-46104, -46105, -46106) became well-known ARA receivers without
any change except nomenclature label ("PART OF ARA" versus "PART OF RAV").
The first two RAV receivers (CBY-46102 and -46103) became ARA receivers
(CBY/CCT-46129 and -46145) after the antiquated loop antenna posts and switch
were removed.  (Oddly, those same loop antenna posts and switch re-appeared 
on the later R-23 and R-24/ARC-5.)

> And there is this: We have lots of original wiring diagrams for using
> the ARB and R-26 in a liaison role; why don't we have any for RAX?

Robert cites from SHIP 242A the RAX-1 as a liaison receiver for the GO-9.  I
think that Mike's PB4Y-2 photos clearly show the RAX-1 as a liaison receiver
for the ATC.  There must somewhere be radio system installation diagrams that
show this...but I don't have anything.

But that's not too unusual.  For an unrelated system, the use of the AN/ARR-1
with the CBY-46145 or BC-946-B (in which an AN/ARR-1 control box or antenna
relay is neither required nor desirable), or even the USAAF use of the AN/ARR-1
with the SCR-269 or AN/ARN-7, pictures can be found or recovered aircraft
examined which show the expected configuration, even though I personally have
never come across any associated wiring diagrams.

I'm cross-posting to the ARC5 list just to solicit other views on the 
**originally** intended role of the RAT, RAV, and RAX.

73,
Mike / KK5F