GB581323A - Improvements in or relating to amplifier valves for high frequencies of the grounded grid triode type - Google Patents

Abstract

581,323. Thermionic valves. LIEBMANN, G., and CATHODEON, Ltd. Nov. 20, 1941, No. 14916. [Class 39 (i)] In a high-frequency triode of the type in which the output is connected between the grid and anode, and the modulation applied to the cathode, the electrodes are in the form of co-axial cylinders and the grid 4, Fig. 1, is conductively secured to a shielding disc 3 between the anode and cathode leads. The shielding effect is completed by a metal cap 9 over the other end of the grid. As shown, the grid supports are carried on the shielding disc 3, and support through mica spacers 5, 6, the anode 8 and cathode 7. The complete mount is supported on the stem 11, and, in assembly, may be secured to a disc 2 sealed through the wall of the envelope 1, with the anode lead connected to a cap 10 at the opposite end. When used with a concentric line circuit, the anode lead may be in the form of a tube sealed through the envelope as described in Specification 553,350, [Group XXXVI]. An alternative arrangement is shown in Fig. 4, in which the anode and cathode are connected, respectively, to discs 22, 23 sealed through the envelope and connected to tubes 31, 32 forming the inner conductors of a concentric line system of which the outer conductors are formed by tubes 33, 34, tuning being effected by adjustable pistons 35, 36. Another arrangement is described, Fig. 2 (not shown) in which all the leads are taken through a moulded glass base of the envelope. In this, the shielding disc has a bent portion isolating the anode lead from that of the cathode. In arrangements where the leads pass out of the envelope at opposite ends the shield may have an upper or lower tubular skirt or both. To facilitate degassing, the discs 2, 3 are preferably of copper and the anode of nickel ; alternatively, the anode may be of iron, preferably an alloy of high magnetic permeability and non-rusting or plated with nickel, and the disc of copper or nickel. A suppressor grid may be interposed between the anode and grid and electrically connected to the latter or to an independent source of potential.