GB684041A - Improvements in or relating to the tuning mechanism of radio apparatus - Google Patents

Abstract

684,041. Radio receiving apparatus. ELECTRIC & MUSICAL INDUSTRIES, Ltd. April 26, 1951 [April 26, 1950], No. 10226/50. Class 40 (v). A tuning mechanism comprises a number of adjustable elements mounted on a movable carriage, in which movement of the carriage brings the elements successively into circuit and, at the same time into position for adjustment by manual tuning means. As applied to a superheterodyne receiver, coil formers 5 are mounted between a rear disc 3 and front disc (not shown) whereby upon rotation of shaft 4 they may be brought successively into circuit by engagement of corresponding contacts 11 with a set of fixed contacts 12. Each former carried a pair of variable inductances, respectively, for aerial and oscillator circuit tuning, having ganged iron cores which may be adjusted by means of threaded rods 13 passing through corresponding holes in the front disc. Attached to each rod 13 is a conically-shaped cam 20, the end 14 of which forms one member of a dogclutch ; the other member 15 is attached to the tuning device 17, being normally held out of engagement by a spring. Depression of the device 17 causes the member 15 to engage which ever of the tuning elements has been brought into circuit, adjustment of this element being then effected by rotation of the device 17. The tuning position is indicated by means of a fixed scale and a pointer, Fig. 1 (not shown) coupled to a bell-crank follower member 21 which rests on the surface of the cam 20 concerned; alternatively, each of the spindles 13 may carry a separate circular tuning scale,