Patent GB-814500-A (GB)
Title: Improvements in or relating to tuner devices for radio receivers
IPC: H03J5/12
Filed: 1957-02-27
Abstract: 814,500. Adjusting radio apparatus. GENERAL MOTORS CORPORATION. Feb. 27,1957 [March 9,1956], No. 6568/57. Class 40 (5). A tuner may be controlled by a power or manual drive through a common clutch or by one of a plurality of pre-set push-buttons. As described, the power drive has stop-on-signal facilities. The tuning of coils 10, 12, 14 is simultaneously adjusted by movement of iron dust cores 16 having shanks threaded into a ganging bar 18, which is linked to a treadle-like rod assembly 26 controlled by push-buttons 46 as described in Specifications 649,360, 660,480 and 804,785. Continuous manual tuning.-Rotation of a knob 94 coupled to a worm 100 causes rotation of the worm-wheel 98, attached to a clutch plate 58 and a sleeve 59, all loose on a shaft 34. The clutch 56, 58 is normally held engaged by a spring 62, hence the manual drive may be transmitted via clutch plate 56, fast with shaft 34, to the end member 32 of the treadle assembly. Push-button tuning.-When any push-button 46 is depressed a projecting foot 90 engages one of the curved fingers 88 on the transverse bar 84, rotating it about a rod 85. A cam arm 82, Fig. 3, at the right-hand end of the bar 84 moves over a roller 92 at one end of the clutch actuator 70, the other end 72 of which is pivoted in a slotted bracket 76, so that the clutch actuator 70 is moved to the left. The sleeve 59 passes through an opening 78 in the clutch actuator 70, the opening having teeth 80 which extend into an annular groove 60 of the sleeve 59. Thus rotary movement of the bar 84 results in release of the clutch by axial movement of the sleeve 59. Further movement of the push-button 46 results in the treadle assembly 26 driving the cores 16 to a predetermined setting as described in Specification 649,360. Stop-on-signal tuning.-Fig. 2 shows how axial movement of the shaft 102 is translated into rotary movement of the treadle assembly 26 by the worm 100 acting as a rack on the worm-wheel 98. A Y-shaped member 110, pivoted at 114, has pins 120 projecting into an annular groove 108 at the inner end of the shaft 102 so that a spring 122 stretched between member 110 and the frame may be used to provide power tuning. The motion is governed by an air vane 184 driven by a gear train from a pivoted carriage 132 coupled to member 110 by a link 118. When a signal is tuned in a control relay 220 is released, thus allowing a detent 224 to engage the air vane 184 to arrest the motion. The power tuning scan may be continued by momentarily energizing the control relay by means of a switch 260 manually actuated by the bar 268. Fig. 8 shows the gear train wherein two plates 136, 138 fixed to the frame carry the carriage 132 pivoted on shaft 164 and attached to the link 118 by an extension 196. The gear 170, loose on shaft 164, is fixed to the plate 138 by a screw 171 so that it behaves as a rack driving the pinion 150 as a planet wheel as the carriage pivots about 164. The drive from pinion 150 is transmitted to the air vane 184 via a friction clutch 152, 154 and the rest of the gear train. A pawl-andratchet gear 160, 156 provides one way motion so that no damping is imposed when re-cocking the driving spring 122. This is achieved by solenoid 124 energized by a switch actuated by lugs on the side of the carriage 132. The solenoid 124 attracts a plunger 126 attached to a link 128 which is coupled to an extension 190 on the carriage 132, thus pulling the carriage backwards until a further lug de-energizes the solenoid. A projection 218 on the link 128 releases the clutch 56, 58 via a pivoted sector 208 (Fig. 3) when the solenoid 124 is energized, thus preventing the treadle assembly 26 being simultaneously re-set. Since the worm-wheel 98 may be controlled by rotary or axial movement of the worm there is no positive co-relation between the spring drive and the treadle assembly 26, hence the latter is re-set by a further solenoid 228 energized by a switch 246 actuated by pin on a member attached to the end of assembly 26 when the cores are fully forward. The solenoid 228 attracts a plunger 230 which is coupled to a slide 242, similar to those operated by the push-buttons 46, via a bell-crank 238 and a link 240. When the solenoid 228 is energized the clutch 56, 58 is released by the slide 242 by means of one of the curved fingers 88 (see push-button tuning). The solenoid 228 is released when the tuning rod assembly is re-set by the opening of switch 246 by a further pin.