Triode, designed for telephone repeaters, used as a Class A power output amplifier. Manufactured by Western Electric (USA). This type was made from1921 until 1930, replacement tubes were still being made in the '40s. This valve was probably made between 1925 and 1929. 4.2 Volt,1.0 amp directly heated cathode.

Physical Description

Spherical bulb with top tip and 4 pin American UV style base.

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