GB449655A - Improvements in or relating to electron discharge devices - Google Patents

Abstract

449,655. Thermionic valves. STANDARD TELEPHONES & CABLES, Ltd., 63, Aldwych, London. Sept. 20, 1935, No. 26103. [Class 39 (i)] Valves suitable for push-pull amplification at ultra-high frequencies contain in a single enclosing vessel several electrode units each comprising a cathode, a control electrode, an anode, and a fourth electrode between the control electrode and the anode, and the fourth electrodes of all the units are united to form part of a single structure extending to the wall of the vessel to separate the vessel into two portions, one containing the mutually insulated anodes and their separate leads and the other the control electrodes and cathodes and their leads. Two helical screen-grids 42, Fig. 1, are connected to a flanged shielding disc 37 extending across the vessel 10 and co-operating with an external metal shield 51. Outside the grids 42 and in the space below the disc 37 are helical suppressor grids 32 and anodes 34 with cooling fins 35. Inside the grids 42 are control grids, consisting of longitudinal rods, and central filamentary cathodes. The anode leads 36 pass through the bottom 12 of the vessel 10, and the control grid and filament leads through the top 11. The suppressor grids are connected to the cathodes. In a modification in which the shielding disc extends across the vessel at the bottom of the electrode units and is connected to the suppressor grids and in which the electrodes are positioned by upper and lower slotted insulators, the screen-grids 42, Fig. 8, and suppressor grids 32 consist of arched wires extending around the cathodes 19 from parallel metal plates 68, 74 forming a condenser coupling between the grids 32, 42. The control grids 25 are helices supported by flanged metal plates 47 and the anodes 34 have cooling fins 35 formed as shown. A getter of magnesium strip is supported on a small disc below the shielding disc. In another modification, the plates forming the condenser coupling extend as flat or curved discs across the vessel to act as the shielding disc, are relatively positioned at their edges by insulators and carry arched wires 42, 32, Fig. 10, forming screen and suppressor grids between each control grid 25 and anode 34. The wires 42 of each screen-grid may be mounted on a small plate adjustable on the disc 37 which extends across the vessel. In another modification, (Figs. 14 and 15, not shown), the plates carrying the screen-grids and suppressor grids are replaced by concentric cylinders with correspondingapertures for the electrode units, the outer cylinder having a flange extending to the enclosing vessel.