This type of valve was called a Tungar bulb; it is an argon filled half wave rectifier diode. Tungar bulbs were mainly used in battery chargers. They were introduced in 1917 and remained popular until efficient solid state rectifiers became available. This example was intended for fairly high voltage use, the maximum output being 90 volts at up to 6 amps. Its RMA type number is 4B26.

Physical Description

Elongated spherical bulb with a short neck with a re-entrant seal with a metal pin at one end and a Mogul Edison screw base at the other. It is in its original box.

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