Masco MTB-13X
The The Mark Simpson Company (MASCO) was a long-time manufacturer of commercial audio equipment, specializing in PA systems and components. I suspect they got caught up in the excitement and possibilities of the post-war television boom, and jumped into the TV booster market with this little wooden boxed unit.
Like most early TV boosters, this is a simple circuit, with capacitor tuning and a switch for High and Low channel ranges. This one shows its late-1948 origins in the omission of channel 1. Two separate 6AK5s were used, one each for high and low bands. The extra "Fine Tuning" control at the lower left is a variable inductor in the plate circuit of the High Band amplifier tube, to improve the gain. Probably to save money, the unit uses a transformer only for the tube filaments, creating the 120 volt DC plate supply directly from the AC line. MASCO's circuit design got them in some trouble with Consumer Reports, since chassis mounting screws on the back of the all-wooden cabinet were connected directly to one side of the AC line, thus earning it a "Not Acceptable" rating. (Later versions are said to have resolved this issue.)
MTB-13X boosters must have sold pretty well anyway, since this model remains quite available even today. MASCO went on to make several more booster models over the next few years.
Updated May 16, 2004