A power supply circuit for supplying alternating power to a load, comprising: a source of direct current voltage input between a positive and a negative voltage rail; a pair of class E amplifiers configured to receive the DC voltage and to generate an alternating current output signal, the class E amplifiers being arranged in a push-pull configuration; a first harmonic filter at the output of each amplifier, the first harmonic filter being configured to filter out predetermined harmonic components of the AC signal to generate a filtered AC signal; and an output circuit at the output of each first harmonic filter for receiving the filtered signal and feeding the filtered AC signal to a load, wherein the output circuit includes a single rectifier connected between the negative voltage rail of the source and a point in the output circuit such that if the voltage at the point exceeds a predetermined threshold, the single rectifier conducts to cause at least one of voltage and current to return to the source of DC voltage and clamps the point to a predetermined voltage; wherein each amplifier comprises: a switch connected to a first rail of the DC voltage source; and a resonant circuit connected between the first and a second voltage rail of the DC voltage source, wherein operating the switch energizes the resonant circuit; wherein each amplifier forms with a first harmonic filter and an output circuit a circuit half and a transformer interconnects each circuit half; and wherein a second transformer interconnects the output of each circuit half with the load, thereby providing a balanced load. a source of direct current voltage input between a positive and a negative voltage rail; a pair of class E amplifiers configured to receive the DC voltage and to generate an alternating current output signal, the class E amplifiers being arranged in a push-pull configuration; a first harmonic filter at the output of each amplifier, the first harmonic filter being configured to filter out predetermined harmonic components of the AC signal to generate a filtered AC signal; and an output circuit at the output of each first harmonic filter for receiving the filtered signal and feeding the filtered AC signal to a load, wherein the output circuit includes a single rectifier connected between the negative voltage rail of the source and a point in the output circuit such that if the voltage at the point exceeds a predetermined threshold, the single rectifier conducts to cause at least one of voltage and current to return to the source of DC voltage and clamps the point to a predetermined voltage; wherein each amplifier comprises: a switch connected to a first rail of the DC voltage source; and a resonant circuit connected between the first and a second voltage rail of the DC voltage source, wherein operating the switch energizes the resonant circuit; a switch connected to a first rail of the DC voltage source; and a resonant circuit connected between the first and a second voltage rail of the DC voltage source, wherein operating the switch energizes the resonant circuit; wherein each amplifier forms with a first harmonic filter and an output circuit a circuit half and a transformer interconnects each circuit half; and wherein a second transformer interconnects the output of each circuit half with the load, thereby providing a balanced load.