GB1088945A - Driving device for tuning units - Google Patents

Abstract

1,088,945. Tuning adjustment. R. HOPT. June 25, 1965 [July 25, 1964], No. 26993/65. Heading H3Q. [Also in Division F2] A tuning arrangement comprises a rotatable drum carrying adjusting screws 19 which selectively engage a member 24 to alter the tuning, and a cam 18 with the same number of sections as the number of adjusting screws to lift the member 24 away from the screws while the drum is being rotated by knob 31. The screws have flats 20 on their upper parts so that they can slide non-rotatably in the bottom plate of the cam, and pass through threaded gearwheels 21 for axial adjustment. The appropriate gear 21 meshes with a gear 48 on a shaft 47 driven from a subsidiary knob 43 via gears 44- 46. The shaft 47 is journalled in elongated holes in the tuner casing and the gears 21 and 48 are normally kept in engagement by springs 49. As the drum is rotated, the shaft 47 is forced outward until the next gear 21 comes into position. Backlash between the gears is prevented by springs 22 which force the bottom ends of the screws towards one another. The pin 24 rests on the top ends of the screws except when lifted up by the cam, and is attached to an arm 25 pivoted at 25<SP>1</SP> (Fig. 2, not shown) and bearing a toothed sector which engages a gear 26 on the tuner shaft. A cord 29 wrapped round this shaft at 30 is spring-loaded at 28 to urge the pin 24 downwards against the adjusting screws. The drum is located in each position by a spring-loaded roller 33 bearing on notches in the plate. To ensure that the cam can only be rotated in one direction these notches have sides which are unsymmetrical about a radius of the plate (Fig. 3, not shown). An auxiliary switch 59 for range-changing or voltage switching is operated by an arm 58 which engages a pin 56 that can be inserted in one of several holes 57; the pin and holes are repeated for each position of the drum. Modifications.-The springs 22 can be replaced by a leaf spring 23 (Fig. 3, not shown) mounted on the underside of the plate 16 and urging the screws 19 outwards. The shaft 47 can be driven by a separate knob (Fig. 5, not shown), the shaft being pushed in against a spring to effect engagement of the gears 21 and 48. The shaft is not then movable radially. The cam profile can be symmetrical, in which case the notches engaging the roller 33 may permit rotation in either direction.