Patent GB-442326-A (GB)
Title: Improvements in and relating to circuit arrangements for thermionic valves
IPC: H01J21/14
Filed: 1935-02-15
Abstract: 442,326. Thermionic valves. NAAMLOOZE VENNOOTSCHAP MACHINERIEEN-EN APPARATEN FABRIEKEN MEAF, 30, Croeselaan, Utrecht, Holland. Feb. 15, 1935, No. 4983. Convention date, Feb. 23, 1934. [Class 39 (i)] A circuit for amplifying transmitting or receiving ultra-short waves comprises a four electrode valve having a cathode, a control grid, an accelerating grid and a braking electrode so that the electrons transverse a control space, an acceleration space and an exciting space. In one form, Fig. 1b, a valve 1 comprises a flat cathode 2, control grid 3, accelerating grid 4 and braking electrode 5. Metallic bands connected to these electrodes form Lecher systems 7, 8 and 9, 10 sealed into the tube wall at potential nodes, in the vicinity of which the potential leads are connected. The Lecher systems are so arranged that the acceleration space between the grids 3 and 4 is completely out of resonance with the wave length excited. The control grid is given a weakly negative bias and is placed as near the cathode as possible whilst the brake electrode also is given a weakly negative bias. If the valve is used as an amplifier, the input is applied to the Lecher system 7, 8 and the output taken from the system 9, 10. In a modification the four electrodes are concentric cylinders and are coupled to two pairs of concentric cylinders forming two Lecher systems. Fig. 3b shows such an arrangement. A filamentary cathode 15 is surrounded by a control grid 16 with extensions 26, 261, an accelerating grid 17 with extensions 27, 27<1>, and a braking electrode 18. Insulating members 28, 28<1> support and space the two grids and serve to de-tune the accelerating space. The Lecher systems are short-circuited at their ends by condensers formed by the flanges 29, 29<1> on the control grid extensions, the flange 31 on the braking electrode and the plates 30 and 301. The members 271 and 18 are continued as an energy line 32, 33 terminating in an aerial 34 and counterpoise 35. To reduce the current taken by the accelerator grid prior to excitation, the electrons may be deflected, for example by a magnetic field. In one form, Fig. 5, a flat cathode 39 and plates 41 produce two cathode beams which pass through apertures in the accelerating grid 42 and after traversing the excitation space are deflected by a magnetic field or by negatively biassed auxiliary electrodes 45, so as to fall on the grid 42. For push-pull usage, two sets of flat electrodes, one on each side of a cathode may be used, or the arrangement shown in Fig. 5 may be divided along the line X .... X. The Specification as open to inspection under Sect. 91 comprises also a modification of the construction shown in Fig. 1b in which the electron source is a hot wire situated in a recess in the cathode plate 2, and a modification of the valve shown in Fig. 3b, in which the plates 30,31 are sealed by an annular glass member, and the members 34, 35 are sealed by another glass member so that the braking electrode 18 with the plate 30 and the member 32 forms the envelope of the device. This subject-matter does not appear in the Specification as accepted.