GB437788A - Improvements in or relating to electron discharge devices and electrical oscillation generators incorporating the same - Google Patents

Abstract

437,788. Thermionic valves; valve generating and modulating circuits. MARCONI'S WIRELESS TELEGRAPH CO., Ltd., Electra House, Victoria Embankment, London.-(Assignees of Hansell, C. W. ; Port Jefferson, Long Island, New York, U.S.A.) March 20, 1935, No. 8731. Convention date, March 20, 1934. [Classes 39 (i) and 40 (v)] A short-wave high-frequency generator consists of a cathode 2, perforated anode 4 and a negatively-biassed deflecting electrode 6, which as shown extends symmetrically about the anode from the side nearer the cathode to the side remote therefrom. The electron stream from the cathode is accelerated by the anode and due to inequality of potentials in the anode flows say to the right and is deflected round the right-hand part of the electrode ; as it impinges on the stream from the cathode the stream flow around the right hand part deflects the new stream past and forms a flow around the left hand part, this process being repeated and giving rise to the desired oscillations. These are taken up by the support for the anode and may be radiated directly or through a transformer 17 to an antennµ 23. A shield 12 protects the upper pinch 5 from bombardment. The electrode 6 may be of metal or of insulating material which may become charged unevenly and improve working thereby ; if of glass the surface is coated with carbon to reduce secondary emission. Radiation may be increased by suitably dimensioning the anode so that its natural oscillation period corresponds to the frequency generated; or the deflector electrode 6 may be so tuned, or an external radiator may be coupled to the deflector or anode and tuned to the frequency or a harmonic. A condenser 13 with sliding contact 14 is used for tuning in the output circuit. Modulation of the oscillations may be effected by varying the potentials of the anode or electrode or of both to produce keying or modulation of the frequency or amplitude or both; speech waves applied to a microphone 18 and amplified by a valve 19 may be used with the Heising method, CH being the choke. The potential of the deflecting electrode is controllable through the key 22 and, relay 21. Specification 380,201 is referred to.