GB287958A - Improvements in or relating to circuit arrangements and discharge tubes for amplifying electric oscillations - Google Patents

Abstract

287,958. Wade, H., (Naamlooze Vennootschap Philips' Gioeilampenfabrieken). Dec. 24, 1926. Vacuum tubes.-In an amplifying valve having a screening grid maintained at a high potential, means are provided for preventing the passage of electrons to the screening grid when the potential of the anode falls below that of the screening grid. As shown in Fig. 1, a valve with a control grid 2 and a screening grid 3 has a third grid 4 mounted between the screening grid and the anode 5, and maintained at a low potential by a connection with the cathode or with a battery 9. The screening grid is connected with the end or intermediate parts of the battery 9 in the output circuit. The grids may be in the form of wire helices mounted on a re-entrant foot. In the arrangement shown in Fig. 9, the third grid 4 is connected with the secondary winding of a transformer 18, the primary of which is connected between the anode 5 and the screening grid 3, so that the grid 4 is subjected to potential variations opposite in phase to those of the anode. In the valve shown in Fig. 6, the screening grid consists of strips 3 arranged radially and connected at the ends to rings 19. The anode 5 has radial partitions 15 in alignment with the strips, but wider than them. The ends of the partitions are connected to flat rings 14. The partitions intercept electrons tending to pass back to the grid 3. The control grid consists of a wire helix or parallel rings. In the valve shown in Fig. 7 the control grid consists of strips 2 securing the wires 3 of the screening grid. A third electrode 4, kept at a low potential, may be mounted around the screening grid. In another valve an anode with partitions similar to those shown in Fig. 6 has strips mounted transversely on the ends of the partitions and opposite the strips of the screening grid.