Sharp cut-off tetrode, used for amplification in radio receivers and audio amplifiers, manufactured by Marconi Osram Company (UK) in 1933.

Tube is known as catkin tube, used as Class A R. F. amplifier.

The name "Catkin" derives from the prefix "CAT" used on the Cooled Anode Transmitting Valves made by Osram, Catkin being a diminutive of it. They were expensive and troublesome in production and were only produced for about two years.

4 volt indirectly heated cathode.

Physical Description

Five pin European style base with top cap. External anode construction with protective ventilated housing (Catkin). Perforated metal cover to protect the external anode.

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