GB1170422A - Improvements in or relating to Electric Switches - Google Patents

Abstract

1,170,422. Turret tuner switches. GENERAL ELECTRIC & ENGLISH COMPANIES Ltd., and H. B. S. BRABHAM. 2 Feb., 1968 [31 Oct., 1966], No. 49020/66. Heading H3Q. [Also in Division H1] A turret-type switch connected to a radiofrequency tuned circuit for switching inductive and/or capacitive elements comprises a drum 2 housing inductance coils (not shown) connected to stud contacts 5 arranged in axial rows to co-operate with a fixed row of strip contacts 11, the stud contacts having surfaces which in planes perpendicular to the axis of the drum are substantially concentric therewith, and the parts of the strips which engage the studs are substantially convex (as at 13) such that engagement occurs at substantially the same position along the length of the strip regardless of small variations in angular positioning of the drum 2, whereby the inductance introduced into the circuit by the switch is substantially independent of such positional variations. Each stud contact 5 is fitted into a tubular P.T.F.E. bush 8 and is elongated such that the electrical path length inside a stud does not change much with movement of the point of contact across its domed face. The ends of the strip contacts may have a coating of a gold alloy. The convex end of strip 11 may be provided by indentation (15, Fig. 3, not shown) or by contact stud (16, Fig. 4, not shown). To reduce the capacitance between adjacent studs on the drum 2 these may be made T-shaped with relatively small width in the direction of the drum axis (Fig. 5, not shown), and may be curved in this direction to provide point contact when used with a curled strip end 13 (Fig. 6, not shown). The inductance of strips 11 may be reduced by folding them into a V-shape (19, Fig. 7, not shown). The stud contacts may be fixed and the strip contacts rotatable.