Meaning of beam-power tube

beam'-pow•er tube"

Pronunciation: (bēm'pou"ur), [key]
— Radio. Radio.
  1. a vacuum tube in which the stream of electrons flowing to the plate is focused by the action of a set of auxiliary, charged elements, giving an increase in output power.
Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease.