Abstract: An electron beam tube (1) having an input resonator cavity (2) through which a high-frequency control voltage is applied between cathode (15) and grid (17) of the tube (1), while an annular electrode (8) connected in an electrically conducting manner to the grid (17) of the tube is arranged opposite a metal wall (9) of the input resonator cavity (2) and is connected to a DC power supply lead (11). Interference oscillations are suppressed in that a high-frequency damping material (14) is associated with the DC power supply lead (11) on a part of the length located proximate to the annular electrode.

Abstract: The invention relates to a cathode ray tube having an input resonator cavity which includes a first metal wall (2) and, spaced apart therefrom, a second metal wall (3) each conveying a low electric potential and constituting coupling areas (6, 7) at axially spaced locations, in which areas metal elements (10, 12) conveying a high electric potential are located opposite surface sections (8, 9 and 14, 15) which are electrically connected to the metal walls (2, 3) via insulating dielectrics (11, 13), the coupling areas (6, 7) being separated by a spacing dielectric. A high-voltage stable arrangement which is resistant to temperature fluctuations is obtained in that the spacing dielectric consists of a different material than the insulating dielectrics (6, 7) and has a lower value of the product of loss factor and dielectric constant (tg.delta..times..epsilon.) at a high frequency.