The model TV-101, made by the P.R. Mallory Company, was one of the very first UHF converters offered for sale, in 1952. It was an incredibly popular model, and is seen quite often in flea markets, thrift stores, and antique shops over 50 years later. The TV-101 (or one of its clones) can be found on eBay at almost any time, and generally sell for $5 to $30.
There were two production chassis designs, both instituted in 1952. The earlier model is a three-tube design: a 6AF4 oscillator and 1N74 semiconductor diode mixer, with a 6BK7/6BQ7 cascode IF amplifier and a 6X4 rectifier to provide high voltage from a small power transformer. The later circuit also uses the 6AF4 oscillator and 1N74 mixer, but followed by a 6CB6 IF amp, and with a selenium rectifier stack for high voltage.
All 70 original UHF channels (14-83) were tuned continuously on the big slide-rule dial, and converted to channel 5 (factory setting) or 6. The tuning element was the Mallory UHF Inductuner, which was so successful that it is still available as a component today.
The brown bakelite cabinet is a classic design, and was of good quality. It typically can be polished to a high shine with just automobile polish. I'm told that the circuit was a little hard on the 6AF4 oscillator tube, requiring replacement often.
Mallory also sold the TV-101 to many other companies who needed a UHF converter in their product lineup. Click Here to see a page about the TV-101 with different nameplates ("clones").
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Updated Sept. 6, 2012