Abstract: A process for compensating nonlinearities in an amplifier circuit. An input signal s(t) is amplified to form an output signal y(t) using an amplifier circuit subject to nonlinearities. In accordance with the invention, a predistortion filter is connected upstream of the amplifier circuit. An aggregate signal ##EQU1## is formed in said filter from the input signal s(t) and a predistorted signal x(t) fed back from the output of the predistortion filter, and integrated with respect to time. The predistorted signal x(t) is fed to the amplifier circuit subject to nonlinearities. In this case, the prescribed number n+1 of coefficients k.sub.0, . . . , K.sub.n is determined in accordance with the model ##EQU2## so that for a given input signal x(t) of the amplifier circuit the output signal determined in accordance with the model is essentially identical with the output signal y(t) of the amplifier circuit.

Abstract: In an adjustable vacuum condenser, in which two interengaging electrode systems are arranged in a vacuum-tight housing, the upper electrode system of which is displaceably connected with the cover of the housing via a set of bellows serving as current feed, the interfering self-inductivity is reduced by adapting the outside diameter of the set of bellows and the inside diameter of the electrically conducting jacket surrounding the set of bellows to one another.