GB485626A - Improvements in or relating to thermionic valves - Google Patents

Abstract

485,626. Thermionic valves. RUDKIN, E. P. Nov. 20, 1936, No. 31774. [Class 39 (i)] A thermionic valve arrangement comprises an evacuated envelope within which are arranged a rectilinear cathode, a control electrode, a main anode 2 an auxiliary anode 3, the control electrode comprising parallel plates 1 electrically connected and arranged at rightangles to the length of the cathode 4, so as to divide the electron stream into a plurality of striµ. The anode 2 consists of a number of parts, preferably in the form of cylinders, and each part has a surface parallel to the cathode and normal to the adjacent control electrode part, which is preferably in the form of an annulus and is arranged in a plane which passes medially through the corresponding anode part. The auxiliary anode is situated beyond or between the main anode parts, and it may consist of a cylinder to which the main anode parts are insulatingly attached or it may be in the form of a wire mesh. A screen grid 6 having its wires arranged opposite the control electrode parts may be provided; other grids may be arranged similarly between the cathode and control electrode and/or between the latter and the anode, for reducing the anode impedance of the valve. The control electrode serves to vary the current to the main anode parts by both deflection and intensity control of the electron striµ and the arrangement may be used as an amplifier, in which case the main anode parts are preferably several times wider than the corresponding auxiliary anode parts. In a modification, suitable for use as a super-heterodyne mixer valve, there is provided a second electrode forming the injector electrode and comprising a series of plates, which are arranged similarly to and in line with the plates of the control electrode and are situated between this electrode and the anode. Screen grids inserted between the electrodes reduce the internal impedance and inter-electrode capacity of the valve, and auxiliary focusing electrodes, in the form of plates provided with rectangular apertures, may be arranged adjacent the cathode so as to assist in the formation of the electron striµ which are directed against the edges of the control electrode plates. In addition, the cathode may be rendered emissive only in those parts adjacent the apertures in these auxiliary electrodes. Variable-mu characteristics may be imparted to the device by suitably shaping the main anode parts 2.