GB262115A - Improvements in thermionic valve generators and circuit arrangements therefor - Google Patents

Abstract

262,115. Soc. Francaise Radio Electrique. Nov. 25, 1925, [Convention date]. Addition to 256,653. Thermionic generators, particularly for short waves, are arranged so that the plate, the high and low tension sources, and other bulky apparatus are at earth potential so far as high-frequency currents are concerned, thereby reducing dielectric losses. For the single-valve arrangement shown in Fig. 1, the earthed filament battery 2 is connected to the filament 10 through coils 9 (shown as straight wires). The plate 12 is connected to earth through an ammeter 3 and high-tension source 1, the large shunting-condenser 4 maintaining the plate at zero highfrequency potential. The grid 11 is connected to earth through a coil 9<a> (shown as a straight wire), a high-frequency ammeter 8, a direct-current ammeter 7 and grid-leak 5, the usual condenser 6 being shunted across the elements 5 and 7. In this way all the apparatus except the filament 10, grid 11, and inductances 9, 9<a> carry substantially no high-frequency potentials. The coils 9, 9<a> are tightly coupled and no capacity beyond the interelectrode capacities need be employed. A grid condenser 14 may however be used for increasing the wave-length, or a coil 15 for reducing it. The additional coil 15 may form an extension of the grid coil 9<a>, the grid being connected to an intermediate point of a short-circuited coil. Fig. 4 shows a symmetrical arrangement of two valves. 13, 13<1>. The plates are connected to each other and are earthed through the source 1 shunted by the condenser 4. The filament supply passes from the earthed battery 2 through the coils 9. 9<1> in parallel. The grid circuits comprise the coils 9<a>, 9b and the common grid leak 5 and condenser 6. Points of opposite potential may be used for exciting symmetrical aeriaJs.