Regency db-400
I.D.E.A. of Indianapolis Indiana, began making the db-400 booster in about 1949. This was their second TV booster, and their first bakelite-cabinet model, and its styling and basic design lasted for a couple years (a long time in the short history of TV boosters). I.D.E.A. marketed their products under the Regency brand name. The db-400 and its successors were heavily marketed in the TV industry trade press.
The circuit consists of two identical 6J6-based amplifiers, one each for the high and low channel groups. Four coils are tuned by moving powdered-iron cores in and out (permeability tuning) by rotating the single tuning knob. A switch selects the circuit needed, and turns the unit on or off. The "ON" position turned on the booster's tubes' filaments but passed the antenna signal straight through to the TV set -- in effect, a "standby" position. The ubiquitous selenium rectifier made the plate voltage, through a small transformer.
The cabinet is standard brown bakelite, with plastic knobs. The typical variations in the swirling of the brown bakelite made for a nice pattern, usually called "mahogany," though I have seen units that were so dark as to be nearly solid black. By contrast, an ivory version in a Plaskon cabinet was also available.
Updated March 5, 2016