In 1944, ARC produced a small number of tunable VHF sets for Navy evaluation. There was never a follow-on contract, though the receivers became the foundation for post war ARC VHF sets produced in the thousands. Shown here is almost the entire installation diagramed in the brief supplement to the ARC-5 manual (missing only the T-89 100-125MHz transmitter). From left to right, MD-7 modulator, R-113 and R-112 receivers (C-29 transmitter control and RE-16 antenna relay suspended above), and T-90 transmitter (125-156MHz.) Both the RE-16, T-89, and T-90 used the same antenna relay contained in the more common AN/ARC-3 sets. The RE-16 also contained a 12H6 rectifier used to rectify the carrier for an antenna voltage indication (as opposed to the the usual antenna current meter), and two control connectors so that a normal HF set antenna relay could be daisy-chained through it. That allowed a single C-29 control box to control both HF and VHF sets. Production figures are said to be in the region of 100 or so. Some of these sets received official nomenclature tags and were actually tried out in the Fleet. The 125-156MHz receiver on the left in the photo above is serial number 3! Others, like this T-90 from the ARC Morgue, had only the model number stamped on the outside.

This equipment used a coax connector between sets that was unique to them. It was a sort of home-brew hardline to minimize losses. Photo below, with some new ones below the originals before silver plating is applied. You can see some of the reproduction efforts for these over in Garaj Mahal (under "Coax connectors").



The transmitters were of fairly conventional design, using a MOPA approach with an intermediate 832 frequency multiplier. for the design. As with all the ARC low volume equipment, these are finished like watches and great care was taken to ensure mechanical rigidity. This was especially important since there was no crystal to establish initial stability - the crystal in the enclosure is for calibration only, identical to the lower frequency units.. A Sylvania SD-838 prototype tube was used as the Master Oscillator - a 28v filament triode that was necessitated by the lack of complimentary tubes to use for a series filament string. Data on the tube is pasted onto the glass envelope. More photos of this transmitter are below.

Front view

Top view



Rear top tag



Right side view of interior

Rear view of interior. Serial # is B2, not 82.

Detail of antenna relay
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