An instantly operational (0.1 sec.) 250 watt UHF communications and telemetry power tube

A discussion of the design objectives of a power tube for use with a solid state device driver is presented. In particular, the limiting element has been the cathode heating time. Heater-on to operational time for conventional power tubes has normally been 30 to 45 seconds. Push to talk operation suggests heater-on to operational time of 0.1 seconds. Such a tube has been designed and developed. The design approaches attempted and the final results are presented. Numerous illustrations are included. The final cathode structure, when incorporated in a 250 watt UHF radial beam tetrode power tube, has demonstrated satisfactorily the objective of an instantly operational requirement. Furthermore, the tube has retained its original UHF electrical characteristics. In communications and telemetry service a power tube with this design feature can result in a major conservation of power during stand-by periods, and the ultimate life of the system may be greatly extended when the duty cycle is favorable.