GB624969A - Tuning mechanism for radio apparatus - Google Patents

Abstract

624,969. Push-button tuning mechanism. GENERAL MOTORS CORPORATION. July 18, 1947, No. 19255. Convention date, Aug. 3, 1939. [Class 40 (v)] In a push-button tuning mechanism for radio apparatus in which continuous tuning is provided through a clutch, operation of any of the push-buttons automatically affects a clutch disengagement, and removal of a push-button for adjustment purposes causes the clutch to remain engaged. As shown in Figs. 2 and 3, the manual tuning knob 107 operates through worm gearing 67, 99 and clutch plates 69, 83 to drive the spindle 1 of the tuning elements 3. When a push-button 175 is depressed, the rod 327 closes the switch 301 to energize the electromagnet 89 and disengage the clutch plates 69, 83, making the manual tuning inoperative. Simultaneously, the cam 243 is pushed in until it contacts either of the projections 299, which are attached to the sliding racks 289 and 291. Further depression of the push-button rotates the spindle 115 by means of the pinion 121, in a direction dependent upon the setting of the cam 243 until both ends of the cam are in contact with projections 299, at which position the desired tuning point is reached, the tuning elements being driven through the gear-wheels 111 and 77 driving the shafts 47 and 1. When the button is released, it is returned to normal together with the cam assembly by means of the spring 235. Each push-button may be adjusted to the desired station by removing the button 175 which is held in place by a flat spring 215, the adjusting screw 209 being then forced outwards by spring 287. The screw 209 which operates a clamping device retaining the cam 243 in the desired position is unscrewed and the required station tuned in on the manual tuning. The screw is then pushed in and the cam is clamped in position when it contacts both projections 299. With the button 175 removed, no movement of the rod portion 327 occurs to disengage the clutch and by this means the shaft 115 is prevented from rotating during adjustment. The driving mechanism for the tuning pointer and the method of illuminating the dial, pointer and station indicators on the push-buttons are also described.