Triode amplifiers in the frequency range 100 Mc/s to 420 Mc/s

Concentration of effort on the design of valves suitable for the shorter decimetric wavelengths during the war years resulted in there being very few valves available for use in the frequency range 100 to 420 Mc/s other than expensive all-glass ¿disc-seal¿ or ¿lighthouse¿ types. This state of affairs was particularly noticeable in the case of small transmitting amplifiers. It has been found possible, by careful attention-to the geometry of electrodes and leads, to design triode valves capable of operation at frequencies up to 420 Mc/s in grounded-grid circuits, and yet mounted on conventional pressed-glass bases, and using only the recognized techniques of receiving-valve manufacture. This paper outlines the design features requiring special consideration and gives some of the results achieved with various special valve types.