National TVB-1
The National Company, of Malden Massachusetts, was a major maker of Ham Radio equipment, with about 30 years' experience when they jumped on the television bandwagon in the late 1940s. In addition to boosters, National also produced whole TV sets for several years.
The TVB-1 was National's first TV booster, made in 1949, and its circuit design reflected Ham Radio state of the art for VHF amplifiers. To cover the wide frequency range, there were two 6AK5-based amplifiers, one each for the high and low TV channel groups. A variable capacitor tuned each tube grid, and a switchable tapped coil provided broadly channelized tuning for the plate. A 3-position switch selected the desired band, and the "off" position bypassed the amplifiers. A separate power switch meant you could keep the tubes lit and ready at all times (common for Ham gear, but hardly necessary for TV watchers). DC voltages are created straight from the AC line with a selenium rectifier, with a small transformer for the tube filaments. The chassis is of a thick grade of steel, plated with copper.
The cabinet is standard brown bakelite, with plastic knobs. The cabinet is the same as used in National's "Select-O-Ject" audio filter, a Ham radio accessory. The knobs are typical National knobs of the period, but in brown rather than the usual National gray color. The TVB-1 sold for $39.95.
Updated February 29, 2007