GB278317A - Improvements in or relating to thermionic valves - Google Patents

Abstract

278,317. Tourne, C. Sept. 30, 1926, [Convention date]. Addition to 273,293. Vacuum tubes. - A valve with means for renewing a filament according to the parent Specification, has an additional clamp for gripping the filament. As shown in Figs. 1 and 16, the movable clamping system consists of a main clamp 8<1> and an auxiliary clamp 8<11> in planes at right angles, the fixed clamp 8 has flat and inclined portions 15, 14 respectively, and the guide tube 7 is flattened at the end, and is recessed to receive the end of a spring 19 gripping the filament 5. In order to renew the filament the clamps 8', 8<11> are lowered by means of the soft iron rod 10, the clamp 8<11> engaging one of the parts 15, 14 and the clamp 8<1> engaging over the part 14 with the flattened end of the tube 7. Movement in the reverse direction causes the filament to be gripped first by the clamp 8<1> and subsequently by the clamp 8<11> and the filament is unwound from the bobbin 6. The end of the clamp 8 may be shaped so as to form a hook on the end of the filament and facilitate engagement, with the movable clamp. In order to prevent displacement by vibration the bar 10 may be formed with a recess with which a stud 24 on a spring 25 engages. The filament may consist of a cable of fine wires. In a. modification the fixed and movable clamps are mounted from the ends of a bulb and the grid and anode are supported from the bulb at intermediate points. In a further arrangement two or more bobbins are provided for renewing several filaments, and a reduction gear is interposed between the bar 10 and the movable clamps.