Patent GB-821212-A (GB)
Title: Improvements in or relating to reflex klystrons
IPC: H01J25/24
Filed: 1958-02-04
Abstract: 821,212. Velocity-modulated tubes. WESTERN ELECTRIC CO. Inc. Feb. 4, 1958 [Feb. 11, 1957], No. 3625/58. Class 39(1). A reflex klystron is tuned by moving a flexible wall of the resonator by means of a sleeve surrounding the repeller electrode and having apertures through which the repeller support extends so that the repeller is not moved with the wall. A flexible diaphragm forming part of the vacuum enclosure has a central portion secured to the sleeve and to a tuning member which operates to move the diaphragm, the sleeve and the flexible wall. A cylindrical metal body portion 11 of the tube shown is sealed at one end by a diaphragm 12 and at the other end by a support member 13 and a member 14 to which is sealed a platform 15 supporting an exhaust tubulation 21 and a plurality of metal eyelets 17 through each of which an alloy lead-in conductor 19 is sealed by means of a vitreous bead 18. The body portion 11 has an interior flange 31 having accurately machined upper and lower surfaces 32 and 33 respectively and a machined and polished inner surface 34. A slot 23 passing through the flange 31 forms an output transformer and communicates with a waveguide 24 terminating in a flange 25 and a mounting flange 27 between which are sealed a circular window 28 of insulating material such as ceramic and two resonant irises 26 and 40 designed to maintain the external Q of the cavity resonator constant over substantially the entire frequency band which it is desired to transmit. An electron gun comprising a hollow cathode 35, heater 52, beam forming electrode 42, and accelerating anode 55 carrying a grid 61 is accurately located by means of a flange 62 on the accelerating anode 55 which engages the surface 34 of the flange 31, and is secured by brazing or welding the anode 55 to the surface 33 of flange 31. A flexible metal diaphragm 63 of material such as copper carrying a grid 65 has a flange 66 which engages the surface 34 of flange 31 and is brazed to the surface 32 of flange 31. A repeller electrode 70 is insulated by a sleeve 67 from a support member 68 which is brazed to surface 32 of flange 31. A repeller lead 72 extends through a hole 73 in body 11 and is insulated therefrom by a sleeve 74 which is retained in position by glass beads 75 or by staking. The lead 72 is connected to the repeller electrode 70 by a lead 76 which passes through a hole in the wall of a diaphragm deflecting sleeve 78 and is insulated therefrom by a sleeve 79. The sleeve 78 is brazed to the diaphragm 63 and comprises two portions which when assembled provide a number of slots 85 through which the repeller support member 68 extends. A stop member 86 is brazed to sleeve 78 and bears against support member 68 to prevent excessive flexure of the diaphragm 63. A central portion 89 of the diaphragm 12 extends into the sleeve 78 and is brazed thereto. Movement is imparted to the sleeve 78 by a tuning member 91 having an upper threaded portion 92, a flange 93 which is brazed to the central portion 89 of diaphragm 12 and a lower portion 94 which extends into the sleeve 78. The tuning member 91 is controlled by a differential screw mechanism comprising an internally threaded mbmber 97 which is clamped by a ring 99 to a cylindrical member 95 which is welded or brazed to body member 11. A drive nut 103 engages the threaded portion 92 of the tuning member 91 and the threaded bore of member 97 and is rotated by means of a cover member 107 secured thereto by screws 108. A stop ring 111 prevents excessive movement of the drive nut 103, and a spring 112 bearing against the flange 93 of tuning member 91 prevents backlash in the mechanism. If the diaphragm 12 is made sufficiently flexible, the spring 112 may be omitted, backlash being prevented by atmospheric pressure. An alternative diaphragm arrangement for sealing the vacuum enclosure and transmitting movement to the sleeve 78 is described with reference to Figs. 5 and 6 (not shown). Cooling fins 122 are fixed in longitudinal slots in the body 11.