Guys, Just came into possession of an interesting rig. Front panel and top lid labeling sez it was made for the US Department of the Interior Grazing Service by the Radio Specialty Manufacturing Service in Portland Ore. No dates.
Configured as a transmitter and receiver in a 10.5X19X16 (HWD) steel cabinet sharing some common PS circuits. The xmitter is crystal controlled, 6K6 osc. driving a pair of 807s parallel connected with a pi output tank. Came with a 2558 xtal in place. Modulated by a pair of 6L6s driven by a 6C8 dual triode driven in turn by a 6Q5 triode speech amp which appears to be setup for an xtal mic. Thordarson CHT multimatch mod transformer. The second 807 appears to have been added later (different socket type and odd placement on the chassis). Receiver lineup: 6K7 RF, 6K8 mix/osc, 6K7 IF (freq unk), 6Q7 det/first audio, 6K7 BFO and 6K6 audio out. There is also a 6H6 which appears to have been used in a squelch circuit which I haven't doped out yet. The 6K8 osc. half appears to have been modified for xtal control somewhere along the line with a (5-pin tube) socket added on the front panel. The osc. coil was left in place, however. Frequency range 1.6 - 3.5 mHz according to the receiver tuning dial. Got it with a 2264 receive xtal in place. I would put construction somewhere in the 40s based on the components used which included cloth covered wiring, Sprague "back beauty" paper caps and a couple of knobs on the front which could only have come off a BC-610 TU. Front panel labeling done with neat little engraved Bakelite and metal plates. Cabinet and chassis custom made with a professional look about them. Many tube sockets and other chassis mounted components riveted in place. The chassis does not slide out: access to the underside components requires removal of a bottom plate. Weighs in at about 60 lbs. Oh yes, 80 LV rectifier and a pair of 866 Jrs. Anyone have more on the rig, company, other, etc? Thanks. Dennis D. W7QHO Glendale, CA
