Characteristics of the UV-858 Power Tube for High-Frequency Operation

This paper indicates the need for high power vacuum tubes for high-frequency transmission, and discusses new factors most important in the design of a tube for this usage. Older types of tubes were built with high efficiency, low-frequency use in view, with the result that when applied to high frequencies they were severely limited by allowable operating voltage and by large internal capacitances and inductances. However, by operating class B amplifiers and thus dispensing with the power modulator, and by minor sacrifices in efficiency in class B or class C operation, it is possible to design a tube having greatly increased high-frequency rating, although it has no usual advantage at low frequency. The actual design of such a high-frequency tube and the resulting characteristics and ratings are given for the UV-858 Radiotron. From these data some of its important uses are indicated and its possibilities in such uses may readily be estimated. Results of special tests involving new phenomena, possible for the first time with this tube, are given.