Complete set, with CBY-23155 remote control above to the right. Still to be fabricated are the connecting cables and flex tuning drive cables from receivers to control box.
On 24 June 1939, the Navy awarded Aircraft Radio Corporation its first
contract for what would become the "command receiver" so well known by countless flight crews and radio amateurs
after the war. This is a relatively complete set of that first production contract, for the RAT
equipment. An earlier one, for the Type K set, was issued in 1937 under a "Confidential" security
label (roughly today's "Secret" level) but that was for a small quantity prototype run for
evaluation purposes and was never fielded as was the RAT. (See
ARC Type K for photos of the
receivers from that earlier set. It was a prototype set that had many of the same features but had a slightly different size and shape.)
The contract included a similar series of RAT receivers nomenclatured RAT-1, the only difference being the operating voltage of 28 volts
rather than the 14 volts required by the RAT sets. Serial numbers for those started at 1 as well.
As far as documentaion for this set, it gets a little complicated. There were two "official" manuals issed for the set, with a four page insert (presumably for the Preliminary RAT manual)
that covered installation of the first RAT set - nomenclatured XRAT - the "X" being a Navy expedient for identifying an operational prototype that was generally
issued in small quantities for Fleet evaluation. The Preliminary manual does not contain anything about the 28 volt RAT-1 set, and therefore has fewer pages in it. The Preliminary
manual (including the XRAT installation insert) is located HERE.
A copy of the Final manual is located HERE, and it has a paper tag glued on the front cover that sort of admits, "Oops,
we neglected to issue this manual without an official Navy number printed inside, so here it is:" (NA 08-5Q-137) There are some interesting characteristics of the RAT that are not shared
with the hundreds of thousands of command receivers which followed. The
first is the frequency range - 13.5-20MHz and 20-27MHz. The unusually
high frequency range hints at a surveillance role rather than normal
Navy communications. In today's parlance, it might be known as an ELINT
receiver, but there is some debate over the conclusion, as some aircraft transmitters of the 1930s like the GO-**
had bands extending to 27MHz., and the full frequency range set later provided by ARC (nomenclatured RAV) included eight receivers
topped off by a pair thet were identical to the two RAT-1 (28 volt) receivers except for the nomenclature tag. The jury is still out. Other differences in the RAT set from later receivers include serial number
tags for the local control boxes, black lacquered local tuning knobs,
and ceramic tube sockets rather than mica filled phenolic. Also note
the lack of covers for the A/B tel. switches on the front of the receiver
rack. Later racks extended the threads on the switch so that a small cover
could be screwed on to prevent inadvertant toggling.
The tube lineup was the same as the later ARA and SCR-274N sets, which meant
the 12SK7 used as the RF amplifier was being pushed a bit hard to get up to 27MHz.
Production figures are hard to come by for this and the RAT-1 set, but the consensus
seems to be narrowing to about 50 for each set, based on the remaining set and peripheral serial numbers.
I'm keeping a list of the surviving sets, so if you have one, please send serial
numbers and accessories (all ownership data is being kept confidential unless the owner
permits sharing this information.) Other views of this set can be seen below. These receivers do not have a great deal of selectivity,
requiring the preselector suspended above them to be halfway useful on
the amateur bands. The preselector was made from a scrapped ZB-3/ARR-1 shell to
maintain the same "look" as the rest of the WWII sets. The "dial lock" at upper right
is actually a push-pull band switch from a scrapped Tektronix scope plug-in for the two bands being covered. The RATs are being
used with much lower B+ to ensure their preservation for posterity...the capacitors are over eighty years old. They work fine in this
mode, though an amplifier is necessary to get enough drive for earphones or speaker. The
RL-5 interphone amplifier to the right is being pressed into service for that purpose.
The dynamotors shown below are not original, as the finish on the originals is gloss black, not black wrinkle. One original has been found for this set to date, but I am still looking for another if one happens to pop up in your junk box.
