Abstract: A transmission line cavity comprises an outer conductor and a center conductor. The cavity is in combination with a source, such as a power tube, for establishing electromagnetic waves within the cavity. The impedance of the center conductor may be changed, for example by changing the series inductance, to vary the resonant frequency of the cavity.

Abstract: An improved high power electron tube has at least one grid electrode. The grid electrode is formed from a one piece cylindrical member, closed at one end, having an outside diameter, D. The cylindrical member has a plurality of arcuate, circumferentially elongated apertures extending therethrough. Each of the apertures has a length x and a width y wherein the length x is greater than width y, and wherein the length x is not greater than 0.55 times the diameter, D, of the electrode. The width y, of each of the apertures is not greater than 0.1 times the diameter D, of the electrode.

Abstract: Coaxial, one-quarter wavelength resonant primary and secondary resonators are employed in conjunction with a tetrode tube to provide, for example, 55 Kw (kilowatts) of output power for VHF, high-band television broadcasting. Coupling between the two resonators is accomplished by connecting an inductance between the center conductors of the resonators. The effective inductance of this connection is varied (and thus the coupling of the resonator circuits is also varied) by the addition of a variable capacitor in series with the inductive connection.