A tetrode in a holder, manufactured by Marconi Osram in England, introduced in 1927.

Tetrode (or screen grid tube) is used in high frequency amplification. Feed back from anode to control grid was virtually eliminated by uising a screen grid between them.

A 6 volt dull emitter filament operating with a current of 0.25 amp.

Physical Description

A double ended, double base tube with three pins at one end and two at the other.

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