GB746753A - Improvements in or relating to valves of the travelling wave type - Google Patents

Abstract

746,753. Travelling wave tubes. TELEFUNKEN GES., [formerly TELEFUNKEN GES. FUR DRAHTLOSE TELEGRAPHIE]. Sept. 30, 1952 [Oct. 1, 1951], No. 24410/52. Class 39 (1). In a travelling wave tube supporting means for the gun electrodes project from one side of support member 1 and tube 3 in which the helix 4 is located extends from the opposite side of member 1, the member 1 extending perpendicular to the tube axis, and the gun and its supports are enclosed in a tube envelope portion 14 which may be formed in part by common supporting member 1. In one form metal rods 2 serving as gun supports and leads are sealed through glass or ceramic envelope base 1. They may be spaced unequally around a circle, rod 2 connected to helix 4 in particular being widely spaced from the other rods. Glass envelope portion 3 which is in contact with the helix 4 directly or through intermediate angularly spaced insulating strips is sealed to base 1 using a jig to make it accurately concentric with the circle of rods 2 and with its axis parallel to rods 2. The gun electrodes comprising indirectly heated cathode 7, wehnelt cylinder 6 and anode 5 are assembled as a unitary structure by ceramic supports 9, 10 and mica member 11 mounted on three supporting rods 12, and this structure is then threaded over three rods 2 and attached thereto by eyelets 13. Alternatively rods 12 may be dispensed with and the insulating members 9-11 assembled directly on to rods 2, but this is not preferred. The assembly can be precision checked by shining a beam of light through a hole in the centre of cathode 7 along the axis of the system. After final adjustments the envelope is completed by sealing glass, ceramic or metal bulb 14 to base 1 at 15, the device is evacuated and sealed off at 16. In a modification operating with an external coil or magnet for focusing a high-beam current, supporting members 2 are secured to base 1 but do not pass through it, and separate current leads to electrodes 4-7 are taken through the envelope portion near the cathode. If base 1 is of metal, a similar construction is used to the latter case, separate current leads being taken through a glass base at the upper end of 14. In another modification, rods 2 are dispensed with and the gun structure carried on rods 12 is mounted by securing ceramic member 9 to an accurately ground part of the metal base 1 or to an accurately ground intermediate member mounted on the base. The helix may be replaced by any other form of retardation line.