An Analysis of Class B and Class C Amplifiers

A mathematical analysis of the plate-current flow in class B and class C radio-frequency power amplifiers is presented, due consideration being given to the nonlinearity of the tube characteristics and the discontinuity of plate-current flow. A simple and highly approximate equation for the fundamental harmonic component of amplifier plate current in terms of the applied continuous and alternating grid and plate potentials and the load impedance is obtained. Equations for determining the optimum load impedance and proper grid biasing and exciting potentials for maximum power output are derived. Satisfactory agreement is indicated between predicted and experimental outputs for a 500-watt power tube operated over a wide range of exciting and biasing potentials.