Patent GB-428911-A (GB)
Title: Device and method of controlling high frequency currents
IPC: H01J25/36
Filed: 1934-10-12
Abstract: 428,911. Cathode-ray tubes. RADIO CORPORATION OF AMERICA, 30, Rockefeller Plaza, New York, U.S.A. Oct. 12, 1934, No. 29277. Convention date, Oct. 23, 1933. [Classes 39 (i) and 40 (v)] [See also Group XXXVI] Cathode-ray tube apparatus comprises deflecting means for deflecting the beam laterally having substantial length in a direction parallel to the beam and so constructed that the velocity of propagation of the deflecting electric wave along them is approximately the same as the velocity of the beam. This construction may consist in coiling or bending back the deflecting members along which the wave travels, or in coating the members with a magnetic material so as to increase their inductance. In one form, Fig. 6, a tube comprises a filament 31 mounted on spring supports, a U-shaped shield 35 and rectangular members 37, 39 having grid portions 40 and having positive potentials applied to them so that they serve as an accelerating electrode. A glass frame 36 has enlarged central portions on which are wound wire helices 42, 43 serving as control electrodes, and provided with leading-in wires 44, 45, 46, 47. Two flat plates 50, 51 mounted on plates 53, 54 supported from the frame 36 constitute the anodes and are surrounded by shields 57, 58 intercepting secondary electrons. Fig. 9 shows the tube connected in circuit as a detector of high-frequency oscillations. The shield 35 is connected to the filament through a resistance 62. Anode 50 is connected through a condenser 66 to the grid 67 of a triode 68, and anode 51 is connected through a battery 69 and condenser 70 to the cathode 71 of the triode. The shields 57, 58 are connected to anodes 50, 51 through resistances 77, 78. A dipole aerial 79 is connected to a Lecher circuit including the control electrodes 42, 43, a short circuiting condenser 80, and a potentiometer 81. In a tube used in an amplifier circuit, one anode is positioned behind the other at such a distance that the anode currents are 360‹ out of phase, or a negatively biassed electrode is interposed between the two anodes. The tube may be used as an oscillator, the anodes then being connected to suitable points on the Lecher system. A wave meter circuit, Fig. 21, comprises a Lecher system 92 of adjustable length including the control electrodes, and a telephonic or metric, detecting means 94, 95. The condenser 97 is adjusted to give a maximum signal and the distance between consecutive positions of the condenser 96 giving maximum signals is then equal to one-half the wavelength of the signals received by the dipole aerial 93. The tube shown in Fig. 6 may be modified by mounting the control electrodes outside flattened portions of the envelope walls. The control electrodes may consist of flattened helices wound around a pair of backbones. A tube for oscillography comprising a fluorescent screen may have four control electrodes. In another form, Fig. 19, each control electrode 105 may comprise a number of wires 106, 107, 108, 109, 110 connected by condensers and having increasing negative bias maintained upon them to alter the velocity of the beam in correspondence with the closer spacing of the members 106 ... 110. Secondary electrons may be collected by the control electrodes or positively-biassed auxiliary electrodes between the anodes. In another modification, a circular filament with an annular troughshaped shield behind it produces an annular beam which normally impinges equally on a disc and a surrounding annulus which constitute the two anodes. A single helical control electrode is surrounded by a cylinder so that the beam passes between them, and any desired voltage is maintained between them. The pitch of the helix near the anode end is increased so that the beam is accelerated and the wave velocity is correspondingly increased.