Abstract: To increase the frequency without restricting the power and vice versa, of vacuum tubes such as triodes and tetrodes for high-frequency amplification, especially for radio and television broadcasting designers are often limited by the relatively high output capacitance between the anode and the grid of the tube. To reduce this capacitance, especially when the tube is in a circuit for extracting energy from coupled cavities, the cavity coupling is integrated into the tube itself.

Abstract: The present invention concerns a grid amplifier tube producing with an approximately constant gain at least a combination of a first signal for a short duration and a second signal for a longer duration. The maximum voltage of the first signal is higher than the maximum voltage of the second signal. To improve the efficiency of the tube, the anode polarization voltage is adjusted to a level enabling the tube to operate as a class B, AB or C amplifier and to produce the maximum voltage of the second signal but not the maximum voltage of the first signal. The class of the amplifier is made to vary towards class A for the duration of the first signal so that it produces the maximum voltage of the first signal. For this purpose at least one of the polarization voltages of the electrodes of the tube is made to vary. The present invention finds particular application to television transmitters operating in negative transmission systems.

Abstract: In an electron tube with coaxial electrodes comprising an anode, a cathode and at least one grid, the base of each electrode being connected to the outside through a connection, there is mounted between the base of the grid and said connection a solid annular piece having a duct for the passage of a cooling fluid, said duct being connected to at least one fluid inlet tube and one fluid outlet tube.

Abstract: An electron tube with a cathode cooling device comprising an anode, a cathode and at least one grid in which the cathode is connected to an output connection through at least one skirt. Inside said tube, at the level of the connection between said skirt and said output connection, a tubular element is provided comprising a spiral shaped part which is extended by at least one inlet tube and one outlet tube emerging on the outside, said tubular element having a cooling fluid flowing therethrough.

Abstract: The means providing capacitive decoupling between the inside cylinder and a grid electrode are disposed at about one fourth of the wavelength of the highest operating frequency from the tube end of the inside cylinder. This is a current node, and dielectric losses at the highest frequency are thus greatly reduced. The match is less good at lower frequencies, but the corresponding dielectric losses are much less at lower frequencies. The first piston provides capacitive coupling between the first and second cavities whereby the entire outside cylinder may be maintained at ground potential.

Abstract: A directly-heated cathode for power electron tubes such as triodes, tetrodes or pentodes comprises a cylindrical sleeve constituted by a lattice of crossed wires forming the emissive portion of the cathode and by two conductive plates attached respectively to each end of the sleeve. In order to permit free deformation of the cathode, a flexible metallic bellows element is fixed between one of the plates and the corresponding end of the cylindrical sleeve.

Abstract: A frequency band filter includes a plurality of coupled elementary resonator cavities defined by pistons disposed within a coaxial line. The position of the pistons along the line is adjustable thereby providing selectable tuning.

Abstract: A coupling electrode is placed within the vacuum envelope of an electron tube of coaxial geometry which is insulated from the anode of the tube by means of an insulator. The insulator is joined to the coupling electrode and the anode of the tube by means of flanged collars. One of these collars may serve to connect the coupling electrode to one or a number of external circuits. A capacitive coupling is established between a top cap of one grid of the tube, namely the grid cap located nearest the coupling electrode, and the coupling electrode. The distance and therefore the coupling capacitance between the grid cap and the coupling electrode can be made variable by mounting the coupling electrode on a deformable metallic bellows element.

Abstract: A flat grid of pyrolytic graphite is obtained by cutting a disc from a cylindrical blank followed by deformation under pressure and by means of a partial vacuum. The grid is then machined and stretched within a stressing frame which also serves to mount the grid within the electron tube.

Abstract: A device for suppressing parasitic oscillations in electronic power tubes of coaxial structure. It is constituted by an electrically conductive component of cylindrical form with a flange, containing an odd number of resonant circuits of the RLC type, with distributed constants. Each circuit comprising at least one inductance coupled to at least one capacitor. The latter are respectively constituted by an opening and a slot in said component. The circuits are tuned to the range of frequencies of the parasitic oscillations.

Abstract: A cylindrical grid for an electronic tube, a triode or tetrode, of high-power design. It is constituted by a mesh-type structure of pyrolytic graphite, the meshes being substantially of equilateral triangular shape in all cases.

Abstract: The present invention relates to an electronic tube with cylindrical electrodes. In tubes of this kind, where the cathode generally consisting of a wire mesh 1, the space located within same is tightly coupled with the other inter-electrode spaces of the tube. The invention, in order to avert parasitic resonances at the harmonics closest to the operating frequency, which can occur in said space in operation, provides for the arrangement in said space of a certain number of metal sleeves 8, 9 and 10 coaxial with the electrodes, constituting low-inductance coaxial line sections.Application to high-power, short-wave (20 MHz) triodes for transmitting applications.