US2297152A - Automatic radio tuning control - Google Patents

Description

Sept. 29, 1942. w. L. JACKE AUTOMATIC RADIO TUNING CONTROL Filed Nov. 20, 1928 2 Sheets-Sheet l V A/WAIAI ir/I INVENTOR mLL/AM L JAG/(E 3 2956 54 27 45 W0 fa ATTORNEYS.

p 9, 1942. w. L. JACKE 2,297,152

AUTOMATIC RADIO TUNING CONTROL Filed Nov. 20, 1928 2 Sheets-Sheet 2 fife 7o 4 cu [o INVENTOR. MAL/AM L. JAG/f5 ATTORNEYS.

Patented Sept. 29, 1942 AUTOMATIC RADIO TUNING CONTROL William L. Jacke, San Jose, Calif., assignor to Philco Corporation Application November 20, 1928, Serial No. 320,667

37 Claims.

My invention relates to improvements in automatic radio tuning controls, and it consists in the combinations, constructions and arrangements hereinafter described and claimed.

An object of my invention is to provide an automatic radio tuning control in which the desired station may be automatically tuned in by the mere pressing of a push button, whether this push button is carried by the set itself or is dis- "posed away from the set, as, for example, in another room. This permits the set to be worked by a remote control.

The device makes use of a plurality of push buttons, each one of which designates a particu lar station. These push buttons are so interconnected as to cause. the releasing of all of the push buttons when a master push button is depressed. Furthermore, the pressing of a different push button will release the previously depressed one, and in this way a new station may be tuned in at will.

A further object of my invention is to provide a device of the type described in which the set is disconnected while the device is tuning in a new station, thus eliminating any noise which would result as the tuning mechanism passes by the undesired stations.

Other objects and advantages will appear as the specification proceeds, and the novel features will be particularly pointed out in what I hereinafter claim.

My invention is illustrated in the accompanying drawings forming a part of this application, in which Figure 1 is a front elevation of a radio panel board showing the device operatively applied thereto;

Figure 2 is a section along the line 2-2 of Figure 1;

Figure 3 is a section along the line 3-3 of Figure 2;

Figure 4 is a detail section of a portion of the device;

Figure 5 is a front elevation of another portion of the device;

Figure 6 is a section along the line 6-6 of Figure 5;

Figure '7 is a rear elevation of Figure 1;

Figure 8 is a wiring diagram;

Figure 9 is a section along the line 99 of Figure 8; and 2- Figure 10 shows a panel board for the remote control.

In carrying out my invention, I make use of a escutcheon plate 2, this plate and panel board having aligned openings designated by the reference numeral 3' for permitting access to stops hereinafter described. In this way the stops may be adjusted and tightened from a point exterior of the set. The plate 3 normally covers the aligned openings 3', and this plate has windows in which the call letters of the stations are placed. A window 4 in the escutcheon plate 2 permits the numbers on the dial 5 to be read. The plate 3 has clips 2' that yieldingly engage with the walls of the openings 3'. In this way the plate is removably secured to the set.

The dial may be manually adjusted by means of a turning knob 6. Reference to Figure I shows that the knob 6 is connected to the dial 5 by a sprocket chain 1 and bevel gears 0.

The dial 5 is mounted upon a shaft 8 that carries the usual gang condensers l0 which are used for tuning in the proper stations.

I provide electrically-actuated means for tuning in the desired station. This means is controlled by a plurality of push buttons II. The push buttons close a circuit to a motor 12 (see Figure '7), and this motor has a friction wheel l3 contacting with the periphery ofthe dial 5 (see Figure 2). The dial is connected to a shaft ll by means of gears l5, l6 and IT. The shaft is insulated from its supporting frame. The shaft ll carries stop pins I8 which in reality are set screws. These set screws are mounted in bushings 83 which in turn are mounted on the shaft, and the set screws extend through the bushings and bind upon the shaft. These set screws extend radially from the shaft I4 and are arranged in a predetermined manner so as to cause the condensers N to tune in the station in question when the set screw associated with this station strikes a small lever 19. There is a set screw l8 and a bushing 83 for each station, and there I is a lever I! for each set screw. Each lever I9 The push button II has a shaft 20 that is provided with a conical-shaped portion 2 I, a reduced portion 22, and a shoulder 23 engageabl with the lever IS. A spring 24 urges the shaft 20 toward the left in Figure 8. The shaft carries a conductor 24 and has its right-hand end secured to a plunger 25 of a solenoid 26.

When the push button II is manually depressed, the conical-shaped portion 2| rides Over a keeper 21. Figure 2 shows the keeper disposed 1, panel board I, and upon this board I mount an on the right-hand side 01 the conical-shaped portion 2|, while Figure 8 shows it disposed on the left-hand side. The keeper 2! is common to all of the push buttons and is urged in a counterclockwise direction by a spring 28. As the push button H i depressed, the shoulder 23 is moved away from the lever l9 and permits a spring 29 (see Figure 8) to swing the lever into vertical position. Th keeper 21 prevents the shoulder 23 from moving the lever I9 back into inoperative position. The lever carries a stop 30 that limits the movement of the lever and holds it in a vertical position. One side of the lever is provided with an insulating portion 3| for preventing the set screw l8 from making an electric circuit until the set screw occupies the position shown in Figur 8.

I will now describe the wiring so as to set forth how the set operates. This wiring includes a switch 32 that is actuated by solenoids 33 and 34. The switch has a rockable member 35 made of insulating material, and the cross section in Figure 9 shows how this member is disposed between conductor clips 36 and 31. Figure 8 further shows how this same member 35 i disposed between a pair of clips 38 and a third pair of clips 39. The member 35 carries two conductors 48 and 4|. The conductor 4| electrically connects either the clips 38 or the clips 39, whil the conductor 40 connects only the clips 36 and 31 together.

When the push button II is depressed, the conductor 24' is moved against a conductor strip 42, and this closes a circuit from a wire 43 through a wire 44, a frame 45, shaft 28, conductor 24', plate 42, wire 46, solenoid 33, wire 41, and wire 48. This energize the solenoid 33 and swings the member 35 into the position shown in Figure 8.

The current flows through the solenoid only so long as the push button II is kept manually depressed. The pressing of the push button is only momentarily done, and when it is released, the

, spring 24 will move the shaft 20 so as to free the conductor 24' from the plate 42, thus breaking the circuit through the solenoid. As already stated, the movement of the shaft 28 to the right permits the lever I9 to swing into an upright position, and the keeper 21 prevents the return movement of the shaft 20.

The throwing of the member 35 to the left in Figure 8 causes the conductor 48 to electrically connect the clips 36 and 3'! together and the conductor 4| to connect the clips 39 together. The current will now flow from the wire 43 to the motor l2, and from the motor through wire 49, clips 39, conductor 4|, and wire 48. This causes the motor to rotate the dail 5, and in doing so the shaft I4 is rotated until the set screw l8 associated with the vertically-extending lever l9 strikes the latter, as shown in Figure 8. This close a circuit from the wire 43 through the wir 44, frame 45, lever l9, set screw l8, wire 50, clip 36, conductor 48, clip 31, wire solenoid 34, wire 52, and back to the wire 48. The solenoid 34 is energized and will swing the member 35 so as to move the conductor 40 away from the clips 36 and 31, and to move theconductor 4| from the clips 39 to an electrical engagement with the clips 38. The clips 38 are connected to th filament or horn circuit of the radio set by mean of wires 53.

Th motor I2 is practically brought to an instantaneous stop when the set screw l8 strikes shut off from the motor, and there will therefore be no undue strain upon the latter.

When another push button II is depressed, the conical-shaped member 2| associated with this push button will move the keeper 2! clockwise about its supporting shaft 54, and this will free the conical-shaped member 2| associated with the former push button, which will permit the spring 24 to return this push button to normal position. In this way any station may be tuned in and the other one automatically disconnected. The rest of the operation is the same as already described.

In case the operator wishes to manually operate the set by means of the knob 6, he depresses a release push button 55 (see Figures 1 and 3). This push button 55 extends slightl in advance of the push buttons H, and is provided with an enlarged portion 56 that ha a conical-shaped end 51 for moving the keeper 21 clockwise for freeing all of the push buttons The shaft of the push button 55 passes into an opening 85 in the plate 42, which prevents the shaft from closing a circuit. Th panel board of the set carries an ofi-and-on switch controlled by a knob 86, and also carries a volume control knob 81.

I also show a remote control for the radio set which permits a loud speaker to be placed in as many rooms as desired and the set controlled from these rooms without the necessity of the operator tuning the set by means of the push buttons II or the tuning knob 6. In Figure 10 I show a panel 15 carrying a number of push buttons 16, a volume control knob 11, and an off-and-on switch 18. The call letters of stations are disposed in panels 19, and these are associated with push buttons I6.

One of the push buttons 16 is shown in Figure 8. When this push button is depressed, it will close a circuit from the wire 43 to a wire 80, and thence through an insulated contact 84, the push button 16, the frame 15, the wire 8|, solenoid 26, wire 82, and back to the wire 48. The solenoid 26 is energized and moves the plunger 25, which in turn moves the shaft 20. The solenoid 26 merely takes the place of the manual pushing of the button The rest of the operation is identical to that already described.

In Figure 3 I have shown a solenoid 26 associated with every other push button II, which means that only half the number of stations can be tuned in by the remote control than can be tuned in by the push buttons II. It is obvious, however, that the solenoids 26 may be staggered with respect to each other so as to associate a solenoid with every push button I The setting of all stations may be done by adjusting the set screws l8 on the shaft l4. After this is done, the mere pressing of the push button will tune in the desired station. The automatic tuning device is small and compact and can be applied to a radio set and occupy unused space in the set. The apparatus is located di rectly under the drum dial and gang condensers, in a space usually found vacant in most sets.

All noise or clicks caused in running over intermediate stations is eliminated when tuning from one station to another, as the radio receiver is automatically disconnected during the working of the mechanism and automatically connected again when the new station is tuned in. The radio receiver may be tuned independently of the automatic control by pressing a center button or the lever i8. At the same time, the current is relea e,

Although I have shown and described one embodiment of my invention, it is to be understood that the same is susceptible of various changes, and I reserve the right to employ such changes as may come within the scope of the invention as claimed.

I claim:

1. An automatic radio tuning control comprising a tuning element, electrically-actuated means for tuning said element, manually-controlled means for closing a circuit to said electric means and including a plurality of push buttons, a keeper common to all of the push buttons for holding a depressed push button in operative position, an electrically actuated switch for closing a circuit to said tuning element actuating means and to the radio circuit, said push button when depressed closing a circuit for actuating said switch, said switch closing a circuit to said tuning element actuating means, and opening the radio circuit, a lever associated with each push button and being free to swing into operative position when its push button is depressed, a plurality oi stops associated with said levers and being swung into engagement therewith when said levers are in operative position for preventing further movement of said tuning element, said stop when contacting with said lever closing a circuit to said switch for causing it to disconnect the tuning element actuating means and to close the radio circuit, said switch when actuated opening the, circuit through said stop.

2. An automatic radio tuning control comprising a tuning element, electrically actuated means for tuning said element, manually controlled means for closing a circuit to said electric means and including a plurality of push buttons, a keeper common to all of the push buttons for holding a depressed push button in operative position, an electrically actuated's'witch for closing a circuit to said tuning element actuating means and to the radio circuit, said push button when depressed closing a circuit for actuating said switch, said switch closing a circuit to said tuning element actuating means, and opening the radio circuit, a lever associated with each push button and being free to swing into operative position when its push button is depressed, a plurality of stops associated with said levers and being swung into engagement therewith when said levers are in operative position for preventing further movement of said tuning element, said stop when contacting with said lever closing a circuit to said switch for causing it to disconnect the tuning element actuating means and to close the radio circuit, a solenoid for actuating said push buttons, and a remote control push button for closing a circuit to said solenoid.

3. An automatic radio control comprising a tuning element, electrically-actuated means for tuning said element, manually controlled means for closing a circuit to said electric means and including a plurality of push buttons, a keeper common to all of the push buttons for holding a depressed push button in operative position, an electrically actuated switch for closing a circuit to said tuning element actuating means and to the radio circuit, said push button when depressed closing a circuit for actuating said switch, said switch closing a circuit to said tuning element actuating means, a lever associated with each push, button and being swingable into operative position by its push button, a plurality of stops associated with said levers and being swung into engagement therewith when said levers are in operative position for preventing further movement of said tuning element, said stop when contacting with said lever closing a circuit to said switch for causing it to disconnect the tuning element actuating means.

4. In an automatic tuning radio control, a rotary element having a plurality of stop members, a plurality of push buttons, each having associated therewith a member for cooperation with said stop members to limit the movements of the said rotary element, common means for holding said push buttons in depressed position in which said associated members are operative with respect to said stop members, and a release push button movable against said holding means for causing it to free all push buttons, thereby to render the stops inoperative.

5. In an automatic radio tuning control, a push button having a shaft, a circuit closed when said push button is entirely depressed, spring means for opening said circuit when said button is released, a keeper for preventing the entire return movement of the push button, an electrically actuated switch operated when the push button circuit is closed, a tuning element, a motor for tuning said element, said electric switch closing a circuit to said motor when said push button circuit is closed, a stop operatively connected to the tuning element and being movable thereby, a lever swingable into operative position when said push button is depressed, said lever being positioned in the path of the stop for limiting the movement of the latter, said electric switch closing a circuit back to itself when said stop and lever contact for causing said switch to close the radio circuit, open the motor circuit, and to break the circuit through the electric switch.

6. In an automatic radio tuning control, a push button having a shaft, a switch closed when said push button is entirely depressed, spring means for opening said switch when said button is released, a keeper for preventing the entire return movement of the push button, an electrically actuated switch operated when the push button switch is closed, a tuning element, a motor for tuning said element, said electric switch closing a circuit to said motor when said push button switch is closed, a stop operatively connected to the tuning element and being movable thereby, a lever swingable into operative position when said push button is depressed, said lever being positioned in the path of the stop for limiting the movement of the latter, said electric switch closing a circuit back to itself when said stop and lever contact for causing said switch to close the radio circuit, a second push button movable for releasing the first push button and lever, a second stop and lever associated with the second push button for causing the tuning element to stop at a different position.

7. An automatic radio tuning control comprising a tuning element, means for actuating the same, a plurality of push buttons controlling the actuating means, a plurality of stops associated with the push buttons for limiting the movement of said tuning element, levers associated with said push buttons and being swin able into the paths of said stops, and means for swinging all of the levers out of the paths of said stops with the exception of the lever associated with the push button depressed.

8. An automatic radio tuning control comprising a tuning element, means for actuating the same, a plurality of push buttons controlling the actuating means, a plurality of, stops associated with the push buttons for limiting the movement of said tuning element, levers associated with said push buttons and being swingable into the paths of said stops, and means for swinging all of the levers out of the paths of said stops with the exception of the lever associated'with the push button depressed, and means for. releasing the depressed push button, said means being actuated by the depressing of another push button.

9. An automatic radio tuning control comprising a tuning element, means for actuating the same, a plurality of push buttons controlling the actuating means, a plurality of stops associated with the push buttons for limiting the movement of said tuning element, levers associated with said push buttons and being swingable into the paths of said stops, and means for swinging all of the levers out of the paths of said stops with the exception of the lever associated with the push button depressed, and means for releasing the depressed push button, said means being actuated by the depressing of another push button, and a remote control for actuating said push button.

10. In a radio receiver, an adjustable tuning element, stop means for limiting the adjustment movement of said element, said means including a member movable with said element, and a second member adjustable into the path of the first member, an electric circuit including said members, and an insulator effective to prevent closing of said circuit by contact of said members except when said members are in the interlocked or operative positions.

11. In a radio receiver, an adjustable tuning element, stop means for limiting the adjustment movement of said element, said stop means including a rotary member movable with said tuning element, and a hinged member adjustable into the path of said rotary member, said hinged member being adapted to be engaged by the rotary element whereby further movement of the latter is prevented, an electric circuit including said members and adapted to be closed when the members are in the interlocked position, and an insulator element carried by one of said members and preventing contact therebetweenexcept in the interlocked position.

12. In a radio receiver, a panel, a tuning element, and means for controlling the adjusted position of said element including a plurality of adjustable elements located adjacent said panel, said panel having an opening affording access to said elements for adjustment purposes, and a detachable cover-plate normally closing said opening.

13. In a radio receiver, the combination with a panel, of a tuning element, means for controlling the adjusted positions of said element including a plurality of adjustable elements arranged in a spaced series adjacent the panel, said panel having an aperture afiording access to said adjustable elements, a series of manuals adjacent said opening and occupying positions corresponding relatively to the positions of said adjustable elements, and a plate detachably secured in a position overlying said panel opening and having areas adapted for reception of various designations respectively corresponding in position with said manuals.

14. In an automatic-tuning radio control, a tuning element, a motor for operating said element, a motor control switch, and electrical means for actuating said switch, a manuallyactuated switch adapted for momentary contact to actuate the said electrical means to close the motor switch, and a third switch adapted to be closed as a result of the resulting motor actuation to thereby re-actuate the said electrical means to open the motor switch.

15. In an automatic-tuning radio control, a motor driven tuning element, a loudspeaker, an electric circuit for controlling the motor, an electric circuit for controlling the loudspeaker, a multiple-circuit switch associated with said circuits and including a pivoted element, and a pair of electrodynamic actuators for selectively controlling said element and attached to the latter symmetrically with respect to said pivot, said circuits being so associated with said switch, that when said element assumes one position the motor circuit is energized and the loudspeaker circuit broken, and when said element assumes another position the motor circuit is broken and the loudspeaker circuit energized.

16, In a radio tuning control, the combination with a tuning element, of means including a pair of interengageable stop members for limiting the adjustment movements of said elements; an

electric circuit including said members, a switch controlling said circuit, and electrical means for shifting said switch; whereby when said switch is closed interengagement of the stop members energizes said electrical means to open the switch and break the circuit.

17. In a selective setting system for a radio receiving set, which set includes an adjustable tuning element shaft; an-electric motor for rotating said shaft, a frictional driving connection between said motor and said shaft adapted to permit over run of the motor when the shaft is held, a plurality of rotatably adjustable stop members carried by the shaft, a corresponding plurality of stops selectively actuatable to move from inoperative position into operative position to be engaged by and positively stop corresponding shaft carried stops, a plurality of electrical circuits adapted to be selectively operated to move selected stops into operative shaft stopping position and to energize the motor to start shaft rotation, and an electrical circuit formed by the engagement of a shaft-carried stop member with the stop previously selected and moved to operative position, to cause de-energization of the motor.

18. In a selective setting system for a radio receiving set, which set includes an adjustable tuning element shaft; an electric motor for rotating said shaft, a frictional driving connection between said motor and said shaft and adapted to permit over run of the motor when the shaft is held, a plurality of rotatabiy adjustable stop members carried by the shaft, a corresponding plurality of stops selectively actuatable to move from inoperative position into operative position to be engaged by and positively stop corresponding shaft-carried stops, a plurality of electrical circuits adapted to be selectively operated to move selected stops into operative position and to energize the motor to start shaft rotation, an electrical contact carried by each shaft-carried stop member, another electrical contact corresponding to each of said first named contacts and adapted to make with its corresponding contact when the corresponding shaft carried stop memto cause de-energization of the motor.

19. In a selective setting system for a radio receiving set, which set includes an adjustable tuning element shaft; an electric motor for rotating said shaft, a plurality of rotatably adjustable stop members carried by the shaft, a correspond- 5 ing plurality of stops selectively actuatable to move from inoperative position into operative position to be engaged by and positively stop corresponding shaft carried stops, a plurality of electrical circuits adapted to be selectively operated to move selected stops into operative shaft stopping position and to energize the motor to start shaft rotation, and an electrical circuit formedby the engagement of a shaft-carried stop member with the stop previously selected and moved to operative position, to cause de-energization of the motor.

20. In a selective setting system for a radio receiving set, which set includes an adjustable tuning element shaft; an electric motor for rotat- 2 tation, an electrical contact carried by each shaft-carried stop member, a corresponding electrical contact carried by each of said selectively actuatable stops and adapted to make with its corresponding contact when the corresponding shaft carried stop member engages its stop, and

an electrical circuit formed by closure of said contacts and adapted to cause de-energization of the motor.

21. The combination of a radio receiver having a tuning shaft, electromagnetic mechanism for operating said shaft, a series of separately adjustable stops movable into and out of operative position, a plurality of members movable with said shaft and each adapted to engage one of said stops for limiting the rotary movement of said shaft to predetermined amounts, said stops being substantially immovable when engaged by said members, so that said shaft is stopped mechanically in selected tuning position, selectively operable electromagnetic means for controlling the position of each stop, and means for automatically stopping the operation of said mechanism in response to the stopping of the shaft in tuning position.

22. The combination of a radio receiver having a tuning shaft, electromagnetic mechanism for operating said shaft, a plurality of electromagnetic devices for limiting the rotary movement of said shaft to predetermined amounts, each device representing a station to be tuned in, a plu- 6o rality of hand-operable members, one for each of said devices, a pair of normally open switches associated with each member and adapted to be closed by said member when the same is actuated,

one switch of each pair energizing one of said devices and the other switch energizing said mechanism, and means whereby the first mentioned switch of each pair is closed in advance of the other switch for energizing any one of said devices in advance of said mechanism.

23. The combination of a radio tuning shaft, a set of movable stops arranged in a row adjacent said shaft and spaced axially thereof, said stops representing certain stations, a plurality of radially and axially spaced means on said shaft for engaging said stops, electromagnetic means for operating any stop to arrest said shaft in predetermined tuning position, means whereby any operated stop remains in stopping position even when said electrommetic means is deenergized, and other means for moving any actuated stop to normal inoperative position.

.24. In a selective setting system for a radio receiving set, which set includes an adjustable tuning element shaft, an electric motor for rotating said shaft, a driving connection between said motor and said shaft adapted to permit overrun of the motor when the shaft is held, a plurality of rotatably adjustable stop members carried by the shaft, a corresponding plurality of stops selectively actuatable to move from inoperative position into perative position to be engaged by and positively stop corresponding shaftcarried stops, a plurality of electrical circuits adapted to be selectively operated to move selected stops into operative shaft-stopping position and to energize the motor to start shaft rotation. and means controlled by the engagement of a shaft-carried stop member with the stop previously selected and moved to operative position, to cause de-energization of the motor.

25. The combination of a radio receiver having a tuning shaft, electromagnetic mechanism for operating said shaft, a series of separately actuable stops movable into and out of operative position, a plurality of members movable with said shaft, each-adapted to engage one of said stops when in operative position for limiting the rotarymovement of said shaft to predetermined amounts-and each being adjustable with respect to said shaft whereby each desired position of said tuning means may be adjustably predetermined, said stops being substantially immovable when engaged by said members, so that said shaft is stopped mechanically in selected tuning position, selectively operable means for controlling the position of each stop, and means for automatically stopping the operation of said mechanism in response to the stopping of the shaft in selected tuning position.

26. A radio receiver having a rotary tuning shaft, means for manually operating said shaft in either direction from one extreme position to the other, a normally inoperative device ad- Justable to stop said shaft in predetermined tuning position, means whereby said device is always free to be adjusted to station-selecting position without preliminary operation of said manual shaft-operating means, said device normally permitting manual operation of said shaft to any position, and a manually operable member adapted to be mechanically connected with said device for adjusting said device to stop said shaft, said member being mounted independently of said device and movable relatively thereto.

27. The combination of a radio tuning shaft, means for manually operating said shaft, a pinrality of members movable with said shaft, each member representing a selected station, a spring finger associated with each member and normally out of operativerelation thereto, whereby said shaft is normally free to be rotated by hand in either direction through its whole tuning range, said fingers being individually operable, a manually shdable pin mechanically associated with each finger for moving the latter to operative position, each pin representing the same station as the associated member, and cooperating means on each member and its finger for stopping said shaft in predetermined tuning position for the station represented by the actuated finger.

28. In a radio tuning device, a series of movable members representing certain stations, a rotary tuning shaft provided with stop means comprising portions arranged in axial and radial displacement on said shaft, a hand knob for rotating said shaft in either direction, and a manually operable push-button mechanically associated with each member for moving said member into the path of said stop means to stop the shaft in tuning position for the station represented by said member, all of said members being mounted independently of said manually operable pushbuttons and adapted to engage the latter in a separable connection.

29. In a radio broadcast receiving set having a unitary tuning system and a manually operable shaft for adjusting said tuning system, means including manually adjustable stop members adapted to be set at predetermined positions corresponding to exact broadcast station frequencies and adapted to lock said adjusting means when said tuning system is adjusted to said station frequencies, means whereby said adjusted members remain in station-selecting position when manually released, and means independent of said members for operating said shaft until arrested by an adjusted stop member, said stop members being incapable of operating said shaft.

30. A combination including a rotatable member; a plurality of adjustable positioning elements mounted on said rotatable member; each positioning element having a set-screw for affixing said element in a pre-determined position on said rotatable membem'a cover plate apertured to expose said set-screws; an index-tab holder attached to said plate and positioned so that an index-tab placed in said holder will prevent at least one of said set-screws from being exposed through said cover plate.

31. A tuning unit for radio apparatus, including a movable tuning element, drive means for said element, switch means for controlling the operation of said drive means, a plurality of manual means each adapted to condition the switch to initiate drive upon actuation of said manual means, stop means including a member mechanically connected to said tuning element for limiting the movement of said element to a predetermined position, an electrical circuit for conditioning the switch to stop said drive means when said circuit is energized, said circuit including said stop means, and said stop means being constructed and arranged to energize said circuit when said tuning element has reached said predetermined position.

32. A tuning unit for radio apparatus, including a movable tuning element, drive means for said element, switch means for initiating and controlling the operation of said drive means, stop means including a member mechanically connected to said tuning element for limiting the movement of said element to a predetermined position, an electrical circuit for conditioning the switch to stop said drive means when said circuit is energized, said circuit including said stop means, and said stop means being constructed and arranged to energize said circuit when said tuning element has reached said predetermined position.

33. A tuning unit for radio apparatus, including a movable tuning element, drive means for said element, stop means movable between operative and inoperative positions for limiting the movement of said tuning element to a predetertion at which said member will stop, an apertured plate providing access to said adjustable means, and an index-tab holder so positioned with relation to said plate thatan index-tab placed in said holder will prevent the adjustable means from being exposed through said plate.

35. A tuning unit for radio apparatus, including a movable tuning element, drive means for said element, stop means movable between operative and inoperative positions for limiting the movement of said tuning element to a predetermined position, resilient means tending to move the stop means toward operative position, means restraining said stop means against the'action of the resilient means, and a manually operable element adapted upon actuation to both initiate the drive and to release the stop restraining means, whereby said tuning element will be stopped at said predetermined position under the influence of said stop means.

36. In a selective setting system for a radio receiving set, which set includes an adjustable tuning element shaft, an electric motor for rotating said shaft, a frictional driving connection between said motor and said shaft adapted to permit over-run of the motor when the shaft is held, a plurality of rotatably adjustable stop members carried by the shaft, a corresponding plurality of stops selectively actuatable to move from inoperative position into operative position to be engaged by and positively stop corresponding shaft-carried stops, a plurality of electrical circuits adapted to be selectively operated to move selected stops into operative shaft-stopping position and to energize the motor to start shaft rotation, and means controlled by the engagement of a shaft-carried stop member with the stop previously selected and moved to operative position, to cause de-energization of the motor.

37. In a selective setting system for a radio receiving set, which set includes an adjustable tuning element shaft, an electric motor for rotating said shaft, a plurality of rotatably adjustable stop members carried by the shaft, a corresponding plurality of stops selectively actuatable to move from inoperative position into operative position to be engaged by and positively stop corresponding shaft-carried stops, a plurality of electrical circuits adapted to be selectively operated to move selected stops into operative shaft-stopping position and to energize the motor to start shaft rotation, and means controlled by the engagement of a shaft-carried stop member with the stop previously selected and moved to operative position, to cause de-energization of the motor.

WILLIAM L. JACKE.

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