Electron tube 4CX250B is forced-air cooled, 250-watt plate dissipation,external anode, and ceramic and metal radial beam tetrode The electron tube 4CX250B/7203 is a forced-air cooled, 250-watt plate dissipation, external anode, and ceramic and metal radial beam tetrode. The superior construction of the 4CX250B makes it ideal for use as a grid driven RF amplifier or oscillator, or an AF power ...