Year of the RAT



On 24 June 1939, the Navy awarded Aircraft Radio Corporation its first contract for 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.)

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 suggests a surveillance role rather than normal Navy communications. In today's parlance, it would be known as an ELINT receiver. Other differences 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 set, but they vary between 50 and 150. 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 for the two bands being covered. The RATs are being used with 28 volts B+ to ensure their preservation for posterity. 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.



Left side view of the complete set



Right side view of the complete set



Left side nomenclature tag



Right side nomenclature tag



Shock mount nomenclature tag
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