Class-A Push-Pull Amplifier Theory

Two tubes operating in push-pull, class-A1, will produce more than twice the power output of a single tube using the same operating voltages, and with optimum load values in each case. This is demonstrated analytically by means of an equivalent circuit. The change in load impedance seen by one tube due to the effect of coupling to the other tube is considered and used to explain the results obtained. Experimental data are presented to verify the theory.