GB400319A - Improvements in or relating to short wave oscillators and apparatus for use in association therewith - Google Patents

Abstract

400,319. Thermionic valves. MARCONI'S WIRELESS TELEGRAPH CO., Ltd., Marconi House, Strand, London.- (Assignees of Hansell, C. W.; Port Jefferson, Long Island, New York, U.S.A.) May 23,1932, No. 14595. Convention date, June 24, 1931. [Classes 39 (i) and 40 (v).] An ultra-short wave oscillator comprises a discharge device having an anode and cathode the electrodes being so arranged and dimensioned that the time of flight of an electron to the anode is substantially one-half (or an odd multiple thereof) of the period of oscillation of the anode and any extension of it, considered as an electrically oscillating body. In one construction, an anode 4, Fig. 1, shaped as a hollow water-cooled tube, as shown in Fig. 1a, surrounds a cathode 2 and grid 16. The anode extends outside the bulb and the distance to a plate 90 is made an odd number of quarter wave-lengths of the oscillations desired. A source 80 keeps the grid-anode potential difference constant, and the cathode is connected to earth through a resistance 60 and capacity 70, thus varying the effective gridbias. In another construction, Fig. 2, the indirectly-heated cathode 2 and the grid 16 are supported from a pinch 10. The anode 4 surrounds them and is supported from a pinch 12. The anode 4 is made one half-wave length long, and a potential is applied to it at its mid-point. The anode may extend outside the bulb. The grid-bias may be made more negative after oscillations have commenced by coupling a rectifier capacitatively to the anode and applying the rectified output to the grid or by connecting the grid to the cathode through a resistance through which the anodecathode current flows. The oscillations may be modulated (1) by means of a key in the anode lead, (2) in telephony by the Heising system in the lead connecting the source of plate potential through a choke to the plate, (3) by connecting the source of plate potential to the plate through the secondary of a transformer the primary of which is modulated, (4) by applying high or low negative potentials to the grid by means of a key and so preventing and permitting oscillation, (5) by modulating the potential difference between grid and cathode, (6) by applying modulation input to the grid of a valve whose plate is connected to the cathode of the oscillator and earthing the grid of the latter. Dimensions of an oscillator constructed in accordance with the invention and as shown in Fig. 2 are given. Specification 379,395 is referred to. The Specification as open to inspection under Sect. 91 also comprises.a receiving arrangement for ultra-short wave oscillations consisting of a thermionic valve having a negatively biased plate, the plate lead coupled inductively to the aerial and earthed through condensers at two different points, and a positively biased grid, the grid lead being in series with the telephones and connected to earth through condensers at two different points. This subject-matter does not appear in the Specification as accepted.