Directly heated triode designed to give satisfactory performance as a general purpose amplifier with its filament operated on an AC supply. 1.5 V directly heated cathode, manufactured by RCA, Harrison, NJ, U.S.A. Anode voltage 180V. Amplification factor 8.2.

The low voltage high current (1.5 V, 1.05 A) filament was designed to minimize temperature fluctuations during the AC cycle and produce a magnetic field that would compensate for the alternating electric field produced by the AC supply.

These valves were used in the RF and audio stages of early AC radios. An indirectly heated valve (UY227) had to be used as the detector but it cost about twice as much as the UX226 so it was only used where it was essential. Once the cost of indirectly heated valves fell, the UX226 became obsolescent. It was renamed 26 in the 1930s and continued to be made for replacement use until the 1950s.

Physical Description

Conical glass bulb with 4 pin UX style base.

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