Optimum Operating Parameters for Class AB Amplifiers†

A theoretical analysis of the plate efficiency and output of a tube operating as class AB radio-frequency amplifier is made. Optimum values of load, C bias, and grid excitation voltage have been calculated which will give maximum output for a given plate loss. Also under these optimum operating conditions the behaviour of a class AB amplifier is analysed in respect of second harmonic distortion. Ready tables and charts are designed from which these optimum operating parameters and the second harmonic content can be readily evaluated.