Calculation of Characteristics and the Design of Triodes

The primary object of the paper is to present a simple method of designing triode vacuum tubes. It comprises three parts; the first part deals with the calculation of characteristics and constants of the triode from the electrode structures, special considerations being taken for applying the formulas already established for tubes of complicated structures. In the second part the derivation of various working conditions of a triode from its static characteristic is treated, in which the writer worked out a graphical representation of d-c and a-c components of the anode working current at various working voltages. The resulting dynamic characteristic diagram is applicable to any type of triodes in evaluating the working voltages, currents and powers, whether the tube be used as an amplifier, oscillator, or modulator. The third part presents the designing procedure for a typical case in which the use of the triode is indicated and its power output is given. First the working points are determined on the dynamic characteristic diagram so as to give the required working condition; then all the quantities arising in the operation are known in their relative amounts. The type of the tube is selected between the high-impedance type and the low-impedance one, which necessitates technical and economical considerations. Then all the quantities are known in numerical values and characteristics of the tube are determined. The electrode structures are calculated to give the required characteristics.