High-performance experimental power triodes

The plate current, transconductance, gain-bandwidth products, and power output capabilities of small planar triodes have been increased by nearly tenfold over that obtained from present day tubes of comparable size and weight. In the new experimental tubes, the cathode can supply a cw current density of 2 amps/cm². A closely spaced, rigidly supported grid structure can provide a transconductance of 0.75 mho. The output capacitance is low enough to render a gain-bandwidth product of 16 Gc at 1.3 Gc. In this frequency range, the cw power output capability is 1 KW and the pulsed power output capability in a 10% bandwidth circuit is 5 KW.