Harmonic Generation

When plate current in a vacuum-tube amplifier flows for only a portion of the grid-excitation cycle, harmonics appear in the output circuit. The magnitude of any one of these harmonics depends upon the fraction of the fundamental cycle during which plate current flows. In the gradual transition from perfect class A to extreme class C operation, the magnitude of the nth harmonic goes through a series of n-1 maxima. To derive the maximum output for any given harmonic, the proper angle of plate-current flow must be chosen. In the present paper the case wherein the plate load is a large pure resistance to all frequencies is considered first. The results of this analysis are then carried over to the case of the tuned-plate-circuit load by the introduction of a simple function. Experimental verification of the analysis is made for harmonics up to and including the ninth.