GB1329920A - Electronic tubes such as tetrodes for very highfrequency operation - Google Patents

Abstract

1329920 High frequency amplifiers THOMSON-CSF 2 Dec 1971 [4 Dec 1970] 56089/71 Heading H3W [Also in Division H1] A high frequency operating tetrode comprises cylindrical electrodes coaxially arranged, within an exhausted enclosure, about the tube axis and consisting, considered successively from the axis of an electron-emissive cathode 21, a controlgrid 22, a screen-grid 23 and an anode 24, together with continuous voltage supplying means for applying to said electrodes convenient biasing voltages. It also comprises input coupling means (not shown) for applying between the control grid and cathode an input high frequency wave, and also output coupling means 120 for extracting an output high-frequency wave between the anode and screen-grid. Tunable coaxial cavities constituted by conductive cylindrical walls 103, 105, 107, 108 arranged coaxially about the axis and prolongate the electrodes to which these walls are connected. A central conductive cylinder 25 coaxially arranged about the axis passes through the cathode 21; the screen-grid 23 is connected to this central cylinder by that one of its extremities which is not connected to cylindrical wall 108. The central cylinder 25 is connected, on the same side as the electrodes, to a conductive cylindrical wall 109 constituting a coaxial cavity with the cylindrical wall 106 extending from the cathode. Ring pistons 111, 112, 113, 114, movable along the coaxial cavities are provided for their tuning, the ring piston 114 movable along that one of the coaxial cavities which is comprised between the walls 106, 109 respectively extending from the cathode 21 and central cylinder 25 is adjusted for ensuring a high frequency short-circuit between the cathode and screen-grid. The coaxial cavity comprised between the walls 105, 108 respectively extending from the control-grid and screen-grid may be tuned for providing a quasi-infinite high frequency impedance between the control- and screen-grids. In the embodiment the cathode is heated by means of a wire mesh 110, a suitable voltage being connected between the coaxial cylinders 105, 106; the various electrodes are maintained in position by means of ceramic rings 44. The Specification also describes what is stated to be a known arrangement (Fig. 1, not shown) in which the electrode connected to the cylindrical conductor arranged within the cathode comprises the control grid.