I.V. Sivchek - Post-graduate Student, St. Petersburg State Polytechnical University. E-mail: cotgreat@gmail.com
V.A. Sorotsky - Dr. Sc. (Eng.), Head of Department, St. Petersburg State Polytechnical University. E-mail: sorotsky@mail.spbstu.ru

New results were published recently which showed that the class E mode known for its rather high efficiency due to switching power loss decline, can be realized in power tube amplifiers. This solution is an extraordinary one as well as original because the power tubes till the recent time were not regarded as a switch-mode devices. At the same time taking into account that some types of power tubes are capable to provide output power in the load as high as hundreds kilowatts at frequencies up to several tens of megahertz, it is evident that neither IGBT nor MOSFETs still can not compete with them in terms of these parameters. Power tubes are able to withstand short-term overcurrents and overvoltages as well as excess losses, thus enabling the class E mode with its rather high values of peak-factors to be combined with the effective use of the devices in terms of output power. The aim of the paper is to provide an improved mathematical model of the class E power tube amplifier as well as methods of its calculation taking into account the voltage drop across the switched on vacuum tube. The paper represents a model of class E amplifier with a harmonic form of the output voltage. Methodics of single-cycle and push-pull circuits design have been developed. Adequacy of the analytic model has been verified by computer simulation. In particular it has been shown that the difference between analytically obtained and PSpice simulated values of efficiency does not exceed 3%.