Patent GB-804785-A (GB)
Title: Improvements in tuner devices for radio receivers
IPC: H03J7/30
Filed: 1956-12-12
Abstract: 804,785. Adjusting radio apparatus. GENERAL MOTORS CORPORATION. Dec. 12, 1956 [Dec. 15, 1955], No. 37941/56. Class 40 (5). A tuner comprises a primary drive mechanism which may be actuated manually from a plurality of adjustable slide assemblies or by power means that may be engaged with the primary drive mechanism when required. As shown, pre-set manual control is provided by push buttons; continuous manual tuning is also provided. The power controlled mode takes the form of a stop-on-signal device. The tuning of coils mounted on formers 2, 4, 6 is simultaneously controlled by movable cores 14 which have shanks 30 threaded into a ganging bar 28 carried by insulating members 32, 36 in slots in the side frames 18, 20. The primary drive mechanism comprises a treadle-like assembly formed by two transverse rods 44, 46 spaced by two pivoted arms 50, Fig. 4, which are coupled via links 56, 58 to the insulating members 32, 36 carrying the ganging bar 28. Manual tuning (1).-Continuous manual tuning is provided by rotation of a knob 87 connected to a flexible drive 86 which carries a worm engaged with a gear mounted on a sleeve 83 which also carries one plate 78 of a clutch 78, 76. A spring 98 normally forces one clutch plate 78 against the other plate 76 thus transmitting rotation via the shaft 80 to the treadle spacing arm 50. Push button tuning.-The primary drive mechanism is actuated by adjustable cams 39 mounted on slide assemblies 38 controlled by push buttons 60 as described in Specification 649,360. An angled foot 62 on each slide assembly 38 releases the clutch 78, 76 through a system of levers. At the onset of movement of any push button 60 the foot 62 strikes a member 64 on a pivoted clutch actuator 66, one end of which is provided with a radial finger 68 which rotates a second pivoted clutch actuator 70. An arcuate operating cam 72, at the right-hand end of 70, acts upon a roller 110 at the end of a lever 102 located in a groove in the sleeve 83, thus releasing the clutch to disconnect the continuous manual drive. Stop-on-signal tuning.-This is obtained by depressing the push button 128 thus bringing into operation the spring drive mechanism at the left-hand side of Fig. 1. The tuner is repeatedly scanned from the lowto the highfrequency end of the band, being re-cocked by a solenoid 232. A control relay 114, which is energized in this mode, is released by the presence of a signal, stopping the motion. The spring drive comprises a main carriage 124, Figs. 2, 9 and a second indexing carriage 122 pivoted to the main carriage 124 at 160. When the push button 128 is depressed, the main carriage 124 is rotated in a clockwise direction as seen from the left-hand side, through a linkage not fully shown in this abridgment. As shown in Fig. 4, the slide assembly 126 controlled by the stop-on-signal push button 128, is locked in its inward position by a latch 164 engaging a notch. When any other push button 60 is depressed, the latch 164 is lifted by the clutch actuator 66 to allow the spring 238 to return the carriage 124 to its upper (inoperative) position. When the main carriage is in its downward or operating position a cam 158, Fig. 7, attached to the side of the indexing carriage 122 is in contact with the stub shafts 154, 156, projecting from the side of the primary drive. The main driving spring 120 urges the indexing carriage 122 in a clockwise direction as seen from the left-hand side, thus scanning the tuning range via the cam 158 and the primary drive. The motion is governed by an air vane 206 driven by a train of gears as shown in Fig. 9. A shaft 224 pivoted at the front of the main carriage 124 is locked by a pinion engaging the worm 218, used for manual tuning. The gear 190 pivoted on shaft 160 is locked since it meshes with a pinion 228 on shaft 224. The pinion 186 thus acts as a planetary gear rolling around the gear 190 as the indexing carriage is urged downwards by the spring 120. When the device tunes to a signal, the control relay 114 becomes de-energized and allows a detent 250, Fig. 2, to engage the air vane 206 thus arresting further motion. The power tuning scan may be continued by momentarily energizing the control relay by means of a switch 266 controlled by a bar 260. When the carriage reaches the end of its travel an adjustable limit stop 234, Fig. 2, energizes the cocking solenoid 232 by throwing over a switch 230. The solenoid resets the carriage 122 to its operating position by providing a rotary motion to the link 233, Fig. 1, the switch 230 remaining closed until the mechanism has been fully re-cocked when it is opened by a second limit stop 236. A pawl and ratchet gear 184, 178, Fig. 9, disconnects the drive to the air vane governor whilst re-cocking. When the push button 128 is depressed, the clutch 76, 78 referred to under Manual tuning (1) is released by a side tip 130 striking an operating finger 132 on the clutch actuator 70. Manual tuning (2).-Continuous manual tuning is also possible when the push button 128 is depressed. The air vane 206 is locked by the de-energized control relay thus locking gears 200, 198, 194 and 192 (attached to 194). The worm 218 is rotated from the knob 87 via the flexible drive 212, thus driving a train of gears terminated in 176. Since 176 is engaged with the locked pinion 192 it must planet around 192 so causing rotation of the indexing carriage 122 and hence the primary drive. Tuning indication.-The setting of the tuner is indicated by the position of an arm 268 coupled to the primary drive mechanism via a bell crank 284.