US2153865A

US2153865A - Tuning apparatus for radio receivers

Info

Publication number: US2153865A
Application number: US160233A
Authority: US
Inventors: Adolph E Gersch
Original assignee: Stewart Warner Corp
Current assignee: Stewart Warner Corp
Priority date: 1937-08-21
Filing date: 1937-08-21
Publication date: 1939-04-11
Anticipated expiration: 1956-04-11

Description

April 11, 1939. A, E. GERSCH TUNING APPARATUS FOR RADIO RECEIVERS Filed Aug. 21, 1937 5 Sheets-Sheet l 7 Ta/ ram Lido hi". Game/z,

April 11, 1939. A: E. GERSCH TUNING APPARATUS FOR RADIO RECEIVERS Filed Aug. 21, 1937 v 5 Sheets-Sheet 2 ,amzaz,

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MEN Q April 11, 1939. A. E. GERSCH 2,153,865

TUNING APPARATUS FOR RADIO RECEIVERS Filed Aug. 21, 1937 Sheets-Sheet 3 Y I l! 25476 47 42 520M235:- 624050/4 l 'Ge ac/z,

, April 11, 1939. A. E. GERSCH TUNING APPARATUS FOR RADIO RECEIVERS 5 Sheets-Sheet 4 Pawerl/ha Filed Aug. 21, 1957 (idol obi? (f 671561 4 April 11, 1939. A. E. GERSCH I TUNING APPARATUS FOR RADIO RECEIVERS Filed' Aug. 21, 1957 5 Sheets-Sheet 5 I daaZ/afz E Ga e/z wwgm Patented Apr. 11, 1939 TUNING APPARATUS FOR, RADIO RECEIVERS Adolph E. Gel-sch, Chicago, Ill., asslgnor to Stewart-Warner Corporation, Chicago, 111., a

corporation of Vir Application August 21, 1937, Serial No. 180,238

- ,16 Claims. (Cl. 250-40) This invention relates .to new and improved tuning apparatus for radio receivers and more particularly to means whereby a. radio receiving set may be automatically tuned to a desired frequency by a selective manual control.

The present-day radio receiver comprises as its .tuning element a multiple unit variable condenser which varies the capacity in a plurality of circuits simultaneously by means of the rotation of a single shaft. The usual tuning control for variation of frequency comprises a rotatable knob which 'serves either directly or through a speed reduction means to rotate the condenser shaft. A calibrated dial is driven from the condenser shaft so that the user may observe the tuning operation and locate the desired station frequency.

While some such dials carry the radio station designations to assist in tuning, this is generally impractical due to the large number of such stationsand due to the fact that such a dial becomes obsolete with changes of frequencies or of station call letter assignments. When the dial is merely calibrated in frequencies, it is necessary for the user'to know the operating frequency of the desired station and to observe the dial carefully and to adjust it slowly when near the desired frequency. The large number of stations on the air renders it diilicult to memorize the frequencies of all stations which it may be desired to receive from time to time.

It is an object of the present invention to provide tuning apparatus for radio receivers whereby the apparatus may be easily and rapidly tuned to a desired station frequency.

It is a further object to provide such tuning apparatus provided with a pluralityof manually operable controls, each of which serves to tune the apparatus to an indicated station.

It is also an object to provide such apparatus wherein the automatic controls may each be easily and quickly adjusted to serve to tune the set to a desired frequency.

It is an additional object to provide a construction in which this adjustment may be car- ,ried out by unskilled persons without knowledge of the details of the mechanism.

It is a further object to provide such an ap-' paratus for the control of a tuning device op- It is also an object to provide apparatus of c this character which may be readily disconnected to permit the usual continuous manual adjustment of the tuning device.

It is an additional object to provide apparatus of this type which will automatically silence the radio receiver during the automatic adjustment of the tuning device.

It is a further object to provide such apparatus which automatically cuts into and out of circuit an automatic frequency control circuit at predetermined portions of the cycle of operation.

It is also an object to provide anapparatus which will automatically control indicating means to show to the user whether the apparatus is adjusted for automatic or continuous manual operation.

It is an additional object to provide an apparatuswf this character, in which the resumption of manual tuning by the user automatically adjusts the mechanism for manual tuning.

Other and further objects will appear as the description proceeds.

I have shown certain preferred embodiments of myinvention in the accompanying drawings, in which- Figure l is a plan view of the control apparatus in position for manual operation, with parts broken away for the sake of clearness;

Figure 2 is a front view of the apparatus of Figure 1, with the dial or indicating mechanism associated therewith;

Figure 3 is a fragmentary view of a portion of the left end of Figure 1;

Figure 4 is a fragmentary view showing a control cam and associated clamping cup assembled on the shaft;

Figure 5 is a fragmentary section of the construction of Figure 4;

Figure 6 is an end elevation taken from the right end of Figure 1;

Figure 'l is a sectional elevation taken on the line 'l'! of Figure l;

Figure 8 is a schematic diagram showing the electrical connections and switches actuated during the operation of the mechanism, with the clutch in automatic control position;

Figure 8a is a schematic diagram showing the cam and cam bar actuating the switch cam of Figure 8;

Figure 9 is a fragmentary view, on an enlarged scale and partly in section, showing the cam disc clamping mechanism;

Figure 10 is a fragmentary view of the clamping mechanism, as seen from the right of Figure 9;

Figure '11 is a cross section taken on the line ll-IlofFigureQ;

Figure 12 is an exploded perspective view of the parts of the clamping mechanism; and

Figure 13 is a fragmentary section showing the friction brake mechanism.

Referring first to Figures 1, 2, 6 and 7, the mechanism is mounted in a sheet metal frame or housing having a U-shaped front member II and a flat rear closure member I2. As shown in Figure 2, this supporting structure II and I2 is mounted on a radio receiver chassis I3 by means of the brackets I4. The chassis I3 carries the dial I8 and indicator I1 by means of standard I5. This indicator I1 is driven by means of cable I8 passing over pulleys I9 and 20 and driven by the pulley 2|, which is driven by means of the gear 22 from the automatic drive mechanism. The gear 22 is driven by gear IOI which is secured to the shaft I02 also carrying the gear I03. The gear I03 meshes with the crown gear I04 which is carried by the' end of the main driven shaft 23. The details of this dial and indicating construction form no part of the present invention and need not be described in further detail.

The automatic control mechanism includes the shaft 23 which extends longitudinally of the housing member I I and is rotatably carried by the

brackets

31 and 38 secured to the housing. As shown in Figure 3, this shaft 23 is provided with the longitudinally extending keyway 24. The stop disc 25 is keyed to the left end of the shaft, and this disc 25 carries the stop lug 28 which en-, gages the stops 21 and 28 at either end of an arc of rotation of 180. Stops 21 and 28 are formed by the upper edges of inturned lugs which are bent in on the bracket member 31.

The shaft 23 supports a plurality of control cam discs 3! which are rotatably carried by the shaft. Between each adjacent pair of control cams 3I are located a pair of clamping cups 32 which are oppositely faced so that the flat flange 33 of each cup engages a cam disc 3|. This is best shown in Figure 5. The clamping cups 32 are all keyed to the shaft 23 in such manner that they may freely slide axially of the shaft, but are constrained to rotate with the shaft. A loeating disc 34 is secured to the shaft 23 adjacent the left face of the bracket 31 by set screw 35,

as shown in Figure 1.

Adjacent the inner face of the bracket 38 the locking cup 30 is keyed to the shaft 23, the righthand face of the cup having a plurality of cam means 36 formed thereon. The cup 39 is rotatably carried on the shaft 23 adjacent the cup 35 and is provided with cam faces 40 coacting with the cams 36 on the cup 35. The cup 39 serves as a bearing for the shaft 23 and itself fits in a circular opening I05 in the supporting bracket 38. Outside the bracket 38, the cup 39 has the gear I08 secured to it, a bearing washer I01 being between the gear I06 and the outer face a of the bracket 38. The gear I06 has the struck up lug I08 on its outer face. The spring I09 is held against the outer face of the gear I08 by the thrust plate H0 which is keyed to shaft 23 to rotate therewith. The thrust plate H0 is held against longitudinal movement along the shaft 23 to the right by the pin III which passes through the shaft. The spring I09 has a raised portion II2 adapted to latch over the lug I08 on the gear I08 in one position of the parts, as will be explained in detail in connection with the operation of the apparatus.

As shown in Figure '1, the frame, formed of members II and I2, carries a plurality of push buttons 4i, each of which is secured to the front end of a station-selecting slide 42. The buttons 4| are in two rows in order to reduce the required linear extent of the control device. This is accomplished by alternately turning upwardly and downwardly the offset forward portion 43 of the station-selector slides, the rear portions of all slides being in the same plane. Each slide is provided with downwardly extending detents 44 which have sloping rear faces 45. The detent latch 48 is carried by the shaft 41 and has a rear portion 48 engaging the sloping surfaces 45 of the detents. The slides 42 are also provided with the upwardly extending clutch bar lugs 49 engaging the, clutch bar 50 which is carried on shaft 5|. The rear portion 52 of each slide 42 passes through a slot in the rear frame member I2. The clutch bar 50 is held against the rear faces of the lugs 49 by means of the spring 55, the free end of which is secured at 56 to the bracket 38.

The shaft 51 carries a plurality of pawls 58 which are freely rotatable about the shaft. The lower portion of each pawl is provided with a turned up extension 59 which engages the front portion ofthe upwardly extending clutch bar lug 49. The forward portion 60 of the lower end of each pawl has connected thereto a tension spring 8|, the other end of which is connected at 82 to an upper extension of the lug 49 of the corresponding key slide 42.

The cam bar 63 is pivotally supported on the shaft 51, the bar extending longitudinally of the assembly. This bar 63 has its upper edge extending against the front face of the row of pawls 58. The upper extension 65 on the cam bar carries the arm 66 which in turn supports the switch cam 81. This switch cam 81 has

low portions

88 and 89 and high portions 10 and H. The cam bar 83 is held in position against the pawls by means of the tension coil spring 12, one end of which is connected to the cam bar and the other end of which is connected to the rear frame number I2.

The switch assembly 13 is supported by bracket II4 from frame member I2 and is provided with nine contact carrying current-conducting spring members which are insulated from each other. The outermost pair H5 and H8 of these contact springs are connected in an automatic frequency control circuit, as best shown in Figure 9 and are in parallel with contacts in another switch assembly II1 operated by the clutch mechanism. The next pair of these conducting

spring members

14 and 15 are connected in a circuit such that when their contacts engage each other the grids of audio amplification tubes are short circuited so that the set is silenced. In other words, these two contacting springs serve to open and close the mute control circuit of the set.

The next pair of contacts 11 and 18 are connected in the power circuit of the automatic control actuating motor 19. The free end of spring H8 is turned inwardly at Hi! to engage an insulating strip I20 held against the face of spring 14. The free end of spring 15 is turned inwardly at to engage an insulating strip 8| held against the face of spring 18. Springs 15 and H8 are normally biased so as to break their contacts with springs 14 and H5, but due to the extensions 80 and H9, an upward or outward movement of spring 18 serves to close the contact between

springs

14 and 15 and between springs III and II8. Due to the insulation 8| and I28, there is no electrical connection between springs and 18 andlbetween 15 and I I8, but merely a mechanical connection. Spring 18 has a downturned end 85 adapted to engage the cam rise 18. As shown in Figure 7, spring 18 is normally biased so as to be out of contact with spring 11, so that the motor circuit is norm-ally open.

.The innermost three

springs

82, 88 and 84 comprise the contacts for controlling the direction of rotation of the actuating motor. With the spring 88 in its normal position, as shown in Figure 7, it makes contactwith spring 84 and the motor will operate in clockwise direction. When the spring 88 is swung to the left, it breaks contact with spring 84 and makes ,contact with spring 82, causing the motor to operate in the counterclockwise direction. The upper or free end 88 of the spring 88 extends inwardly to normally be located at an intermediate portion of the low portion 88 of the switch operating cam 81.

The station selector cam discs 8| are eac provided with a high cam side 81 and a low cam side 88 as shown in Figure 4. These cam sides are on circular arcs of different radii. The station-locating notch 88 is located at one point of junction between the high and. low cam surfaces. The station-locating lug 88 carried by the forward portion of the upper end of the pawl 58 is adapted to fit in the notch 88.

The lug 88 and notch 88 are formed on the same taper, so that engagement of the lug in the notch serves to exactly locate the rotary position of the cam disc 8I and of the shaft 28 to which the disc is clamped during automatic tuning operation of the apparatus.

Referring now to Figures 1 and 6, the motor 18 has on its armature shaft 8| the small drive gear 82 which meshes with the gear 88 which is carried on an intermediate stub shaft 84, which also carries the small gear 85. This gear 85 meshes with the large gear 88 on stub shaft 81. This shaft 81 also carries the small gear 88 which meshes with gear 88, which latter gear is mounted upon and drives the main station selector cam shaft. 28.

The gear 88 is mounted upon shaft 28 in such manner that frictionally controlled slippage may occur between the gear and shaft. The gear 88 is carried by a hub member I88 which is fixedly secured to the shaft by a set screw. The slotted spring I8I holds the gear 88 on the hub so that the shaft 28 normally moves with the gear 88. The slippage permitted at this point is important in preventing damage to the parts should the gear 88 be driven in any manner while a pawl 58 engages a recess 88 in a cam disc. This slip- Page also acts in usual automatic operation as a friction brake to ease the shock of sudden stoppage of the motor armature and gear train when the pawl stops rotation of the shaft 28 upon reaching the proper tuning position.

The armature shaft 8| also carries the manual drive pulley |2| which has the rubber friction facing I22. The manual tuning shaft I28 is carried by the bracket 88 and extends at right angles to the main tuning shaft 28 and below the latter shaft, as clearly shown in Figures 1 and 6. The rear end of shaft I 28 carries the flywheel I24. The forward end of shaft I28 bears in the fixed sleeve I82 which has its rear end supported by bracket I88 extending from the main bracket 88. The sliding gear sleeve I is mounted on the fixed sleeve I82 and bears directly in the main bracket 88.

The sleeve I25 is slidable relative to the shaft I28 and carries the gear I28 which may be moved into or out of mesh with the crown gear I21. The crown gear I21 is fixed on a rotatable stub shaft I28 to which also is fixed a small gear I28 meshing with the cam disc clamping gear I88. The forward portion of the sleeve I25 is flattened on each side at I88 to facilitate its manual rotation and has the flanges I8I to facilitate manually sliding the sleeve outwardly.

The sliding clutch member I 82 is carried upon shaft I28 with which it is caused to rotate by pin I88 fitting in slot I84. This member I82 is provided with the groove I85 to receive the clutch operating fork I88 which is carried by the key bar 58 and moves with that bar. The clutch I face I81 is adapted to engage the rubber facing I22 on wheel |2| to manually drive the shaft 28 through the same gear train as is used in automatic tuning.

The sleeve I88 is loosely fitted on shaft I28. It is prevented from all but a very short longitudinal movement on shaft I28 by pin I88 fitting in slot I48, which permits a limited rotary move-- ment of the sleeve on the shaft. The spring I4I has one end secured to sleeve I88 and the other end secured to the collar I42, which latter is secured to shaft I28 and rotates therewith. The

forward end of the sleeve I88 carries the star,

wheel I48 fixedly secured thereto. This star wheel I 48 is adapted to engage the free end of the unlatching arm I44, which latter is secured to the end portion of the latch plate 48. This arm I 44 is formed with a'downwardly extending portion I45 adapted to enact with the cam end portion I48 of the key bar 58. The lower edge of the forward portion of the bracket 88 has secured thereto the release spring I41 which has a rise I48 adapted to. be engaged by the gear I28, as that gear is moved into or out of mesh with the crown gear I21. The forward end of shaft I28 has the manual tuning knob I49 secured thereto.

The sleeve I82 carries at its forward end the disc I58, which is formed of insulation and serves to operate the switch assembly II1. This switch is shown in the manual tuning position in Figure 6 and in the automatic tuning position in Figure 8.

The switch H1 is made up of five currentcarrying blades, and their connections are indicated on Figure 8. The lower spring I5| is connected to the manual operation pilot light. The next spring I52 is connected to a power supply line of the voltage desired for pilot light operation. The middle spring I58 is connected to the automatic tuning pilot ,light and the other sides of the two pilot lights are connected to the opposite side of the power line from spring I52. As will be seen from Figures 6 and 8, the spring I 52 is normally biased to engage spring I5I to light the manual tuning pilot light. When the sleeve I82 is at the left during automatic tuning, as shown in Figure 8, the disc I58 engages the end I54 of spring I52, lifting it away from spring I5I and into engagement with spring I58 to light the automatic tuning pilot light.

The upper springs I55 and I56 of switch assembly II1 are connected into the automatic frequency control circuit in parallel with the springs H5 and H8 of the key cam switch assembly 18. The end I51 is tumed under to engage an insulating spring I58 resting against spring I52. It will be seen that the circuit between springs I55 and I58 will be closed when the clutch assembly is in the position for manual operation and will be open when the clutch is in the automatic position.

' The automatic frequency control circuit is no part of the present invention and will not be described in detail. It is merely necessary to note that the circuit is such that with the portion of the circuit shown in Figure 8 closed, automatic frequency control does not function. This portion of the circuit is always closed at the clutch switch III when the clutch is in position for manual control, and consequently automatic frequency control is not in operation during manual control.

The automatic frequency control circuit springs H5 and H6 on the key cam switch I3 are normally open, as shown in Figure '7, when no key is pushed in. However, as stated above, in this manual control position the automatic frequency control circuit is out of operation due to being closed at switch Hi. When a key is pushed in, the cam 61 is swung upwardly and spring end 85 is lifted by cam rise I0 and the automatic frequency circuit is closed between springs H5 and H6 regardless of whether the lug 90 rests on a high or low cam side of its corresponding cam disc 3|. Thus, automatic frequency control is kept out of operation even though pushing in the key has opened the circuit between springs I55 and I56. This has been caused by the lug 49 on the key swinging key bar 50 in the clockwise direction, as seen in Figure '7, or in the counterclockwise direction, as seen in Figure 6, which has moved the sliding clutch sleeve I32 to the left by means of fork i36 and lifted switch III through insulated disk I50.

However, as soon as the cam disk 3I rotates to the position where the lug fits in notch 89, the bar 63 is swung further to the right as seen in Figure 7, causing the spring end to pass beyond the cam rise I0, whereupon contact is broken between springs H5 and H6; and since it is also at this time broken between springs I55 and I56 of switch 1, automatic frequency control goes into operation to effect the final tuning adjustment. It is important to have the switch formed by springs H5 and H6 in this circuit, as it is not desirable to have automatic frequency control in operation when the motor drive is automatically tuning the set. This is especially true when the station being sought is close to a powerful station which might cause automatic frequency control to operate adversely before the station sought was reached by the motor drive.

In operating the apparatus to manually tune the set, the parts will be in the position shown in Figure 6. All keys are in the outer or released position. Rotation of the manual tuning knob I48 serves to tune the set in the usual manner. The knob I49 rotates the shaft I23 which rotates the clutch slide I32 which has its face I31 engaging the face I22 of the pulley I2I on the armature shaft 9|. This shaft also carries the first gear 92 of the gear train driving the main shaft 23. Thus turning the manual control knob in either direction causes a corresponding movement of the indicating means and of the radio set tuning device which is rotated by shaft I02. Shaft I02 rotates with shaft '23 due to the coaction of gears I03 and 104.

To put the tuning device in automatic operation, it is merely necessary to select a button and push it in until it is locked in its inner position. Referring particularly to Figure 7, the slide 42 is locked in this position by the detent latch 46 which is forced downwardly by the sloping rear face 45 of the slide detent- 44 and slips upwardly to engage the forward face of the latch 46 as it passes the detent. The latch 46 is swung upwardly by spring I64 shown in Figure 6. As the slide 42 moves rearwardly, it also swings the clutch bar 60 to the left or in the clockwise direction as seen in Figure 7. This is in the counterclockwise direction as seen in Figure 6, and causes the clutch operating fork I36 to move to the left in this figurewhich serves to separate the clutch faces I81 and I22.

Movement of the slide 42 to its locked position also puts a pull upon the spring 6i connected to the slide. The other end of the spring is connected to the forward portion 60 of the lower end of the corresponding pawl 58. This pull therefore swings the pawl 58 in the clockwise direction about shaft 51 as seen in Figure '1. It will be understood that the spring 6I is stronger than spring I2 connected to the cam bar 63 so that bar 68 moves with the upper portion of pawl 58. The pawl 58 moves in the clockwise direction until the lug on the pawl engages the corresponding cam disc 3|.

If the lug 90 engages the high side 81 of the disc 3I, the switch cam 61 is swung through only a short are. This lifts spring contact II6, I5 and I8 when the end 85 of spring I8 engages the cam rise 10 and simultaneously shorts the automatic frequency control and the mute control and closes the motor circuit. merit of cam 6! does not cause it to engage the end 86 of switch spring 83 and the motor direc tion switch remains in the position of Figure 7.

The motor is started and causes the shaft 23 and cam disc 3i to rotate in the clockwise direction as seen in Figure 7. This rotation continues until lug 90 drops into notch 89 in the cam disc. This movement of pawl 58 carries cam bar 63 and the switch cam 61 through a further arcuate movement so that the downturned end 85 of switch spring I8 passes beyond the cam rise I0 and all three switches are opened. The opening of the switches serves to put the automatic frequency control in operation, to open the mute circuit and to. open the motor circuit, stopping the motor. The automatic frequency control completes the tuning adjustment of the circuit.

The operation is generally similar when the lug 90 engages the low side 88 of the corresponding cam disc 3i. The automatic frequency control, mute and motor control switches are all closed in the same manner as when the lug 90 engages the high side 81 of the disc II. The difference in action. is that when the lug 90 engages the low side, the switch cam 61 is swung sufficiently so that the cam rise II lifts the end 86 of switch spring 83, breaking contact with spring 84 and engaging spring 82 so that the motor operates in the opposite direction. This moves the disc 3| in the counterclockwise direction until the lug 90 drops in notch 89 when the operation is as before stated.

To resume manual tuning, it is only necessary to turn the knob I49 in the usual manner. During the automatic turning, the clutch parts have been brought to the positions shown in Figure 8. The first movement of the knob I49 in either direction rotates shaft I23 and the star wheel I43 engages the end of the unlatching arm I44 forcing it downwardly. This'swings the latch This move- 1 bar 43 downwardly, unlatching the key 4i which was last depressed. As the key slide 42 moves forwardly, or to the right as seen in Figure 7, the tension on the spring 3| is released andthe pawl 53 is moved in the counterclockwise direction by the cam bar spring 12 which moves that bar in the counterclockwise direction. This draws the lug 33 out of the notch 33 in the cam disc 3| and releases shaft 23 for manual operation. The lug 33 slips easily out of the notch 33 due to the relative slope of their coacting faces and also because there is at this time no rotary thrust by the cam notch faces against the lug.

Also, as the slide 42 moves to the right in Figure '1, the clutch bar 53 swings in the counterclockwise direction as seen in Figure 7, or in the clockwise direction as seen in Figures 6 and 8,

, under the pull of spring 55 and the clutch slide I32 is moved to the right to the position shown in Figure 8. The clutch is thus brought in operation and the further rotation of the knob I43 serves to manually tune the set.

The engagement between the downwardly extending portion I45 of the unlatching arm- I44 and the cam end portion I43 of the key bar 53 in the unclutched position of Figure 8, has a double function. It maintains the clutch positively in the unclutched position and also positively holds the switch assembly II1 with switch springs I52 and I53 in their upper position.

The importance of the loose connection between sleeve I33 and shaft I23 lies in insuring sufficient movement of the bar I44 when a key is depressed in going from manual to automatic tuning. If the star wheel I43 were rigidly connected to shaft I23 and a key were pushed in with a point on star wheel I43 opposite the upper end of the unlatching bar I44, the movement of the bar would stop at this point so thatit could not be unlatched by rotation of shaft I23 and of the star wheel I43.

To change the adjustment of any or all of .the cam discs 3|, it is first necessary to remove the tuning knob I43. .This knob is preferably of any well knowntype having a friction fit with the flattened end of the shaft I23 so that it is unnecessary to loosen any set screws to remove the knob, which is merely pulled oil.

The flanges I3I -on sleeve I25 are then grasped and the sleeve pulled forward, or to the left as seen in Figure 8, until the gear I23 meshes with the crown gear I21. During this movement, the gear I26 engages the rise I43 on spring I41 and the lower end of the spring thrusts downwardly the unlatching arm I44 to release any key which may be latched inat the time. The fiat sides I33 of the sleeve I25 are then grasped and the sleeve turned in the clockwise direction. Due to the drive between gear I23 and the cam disc clamping gear I 33, this rotation of sleeve I 25 serves to rotate the shaft 23 and associated disc 3| and clamping cups 32 in the clockwise direction as seen in Figure 7. This rotation continues until the stop lug 23 engages the forward stop 21, since no pawl 53 is engaged in a notch 33 due to the automatic release of any key that might have been latched in position.

When the stop lug 23 engages the stop 21, rotation of shaft I23 is stopped. However, the cam cup 33 and the gear I33 arenot keyed to shaft I23 and continue to rotate. This rotation continues until the axial end faces of the

cams

36 and 43 are in substantial engagement. At this time, the raised portion II! of spring I33 latches over the lug I 33 on the outer face of the gear nected to the pawl.

drawn forward to engage gear I 23 with crown this relative position. The cam discs 3| are now no longer positively clamped in position although they are still held frictionally by cups 32 so that they do not turn freely and are not loose onshaft The next step is to press in the button which it is desired to adjust to tune to the selected station. Pressing in this button serves toautomatb,

cally tune the set to the frequency for which the cam disc 3i associated with the button may happen to be tuned. This will take place properly in spite of the fact that the discs are not at this time rigidly clamped. The lug 33 will now be in the notch 33 of the cam disc 3| to be adjusted. and will hold that disc against rotation. The sleeve I25 is next turned to rotate the shaft 23, and the discs other than the disc held by the lug 33, until the indicator I1 is opposite the desired station frequency or until the desired station is tuned in, if the set is in operation. As many more of the discs may be adjusted as desired merely by pushing the buttonassociated with the disc to be adjusted and tuning in the station by means of sleeve I23.

When the desired adjustments have been made, it is necessary to again rigidly clamp all the discs 3 I. It is first necessary to release the associated pawl lug 33 from the disc 3| last adjusted. This is accomplished bymerely pushing in the sleeve I 25 until gear I23 engages the rise I 43 on the release spring I41 and thus releases the key con- After this, sleeve I25 is gear I21 and is rotated in the; counterclockwise direction. This turns shaft 23 and associated parts in the counterclockwise direction, as seen in Figure '7, until the stop lug 23 engages the rear stop 23. Continued rotation of sleeve I25 rotates gear I33 and cam cup 33 so that the cam faces 43 are rotated relative to cam faces 33 on the cam cup 35 which is keyed to the shaft. As this.

takes place, the raised portion II2 of spring I 33 moves away from lug I33 on gear I33. This movement of sleeve I25 continues until the assembly of discs 3i and cups 32 is firmly clamped together.

The sleeve I25 is now pushed to its inner position and the knob I43 replaced on shaft I23. The apparatus is now in adjustment to be tuned either manually or automatically, as explained above.

It will be apparent that both the setting up of stations on the apparatus and its use are simple and may be readily understood by the user of the set. The station selected by any push-button may be readily changed in a moment without the use of tools and without removing the set panel or working in the rear of the set. i

No extra controls are necessary on the front of the set other than the push-buttons themselves. Pushing in any station selector button automatically adjusts the apparatus for tuning by the button if it is not already in the automatic tuning position. A slight rotary movement of the manual tuning knob, as in tuning the set manually, automatically restores the parts to manual, tuning position, if. they are not already in that position. Consequently, the use of the apparatus involves no especial. instructions or operation in changing from one tuning method to the other.

While I have shown certain preferred embodiments of my invention, these are to be under I33 to yieldingly hold the two opposite cam in v and requirements, and I contemplate such changes as come within the spirit and scope of the appended claims.

I claim:

1. In combination with a tuning element of a radio set, a rotating drive shaft having driving connection with said tuning element, a. manually rotatable shaft, a driving connection between the manual shaft and drive shaft, said connection in- .0 eluding a clutch, a motor operatively connected to the drive shaft, a lever for starting the motor,

and means connecting the lever and manual drive clutch whereby said clutch'is released upon moving the lever to start the motor.

[6 2. In combination with a tuning element of a radio set, a rotating drive shaft having driving connection with said tuning element, a manually rotatable shaft, a driving connection between the manual shaft and drive shaft, said connec-- tion including a spring-held friction clutch, and

means whereby rotation of the manual shaft releases the spring and causes the clutch to connect said shaft and the drive shaft.

3. In combination with a tuning element of a radio set, a rotating drive shaft having driving connection with said tuning element, a manually rotatable shaft, a driving connection between the manual shaft and drive shaft, said connection including a clutch, a motor operatively connected to the drive shaft, a lever for starting the motor, means connecting the lever and manual drive clutch whereby said clutch is released upon moving the lever to start the motor, and means whereby rotation of the manual shaft causes the clutch to connect said shaft and the drive shaft.

4. In combination with a tuning element of a radio set, a rotating drive shaft having driving connection with the tuning element, a plurality of cam discs adjustably secured to the drive shaft, each said disc having a high portion and a low portion with a notch therebetween, a locking pawl associated with each cam disc and having a portion adapted to engage the high or low portion and to fit in said notch, a reversible motor for driving said dive shaft, and control switches for said motor operatively associated with said pawls whereby the motor is operated in one direction when a pawl engages the high por-' tion of a disc, is operated in the opposite direction when a pawl engages the low portion of a disc and whereby the motor is stopped when a pawl engages a notch in a disc.

5. In combination with a tuning element of a radio set, a rotating drive shaft having driving connection with the tuning element, a power drive for said drive shaft, a manual drive for said drive shaft, selective stops for said drive shaft, and means whereby rotation of the manual drive releases said selective stops.

6. In combination with a tuning element of a radio set, a rotating drive shaft having driving connection with the tuning element, a power drive for said drive shaft, a manual drive for said drive shaft, selective stops for said drive shaft, keys for actuating said stops, and means whereby rotation of the manual drive releases said selective stops and keys. 7

'7. In combination with a tuning element of a radio set, a rotating drive shaft having driving connection with the tuning element, a power drive for said drive shaft, a manual drive for said drive shaft, keys for putting said power drive in operation and selectively stopping said drive at predetermined points, a clutch connecting the manual drive to the drive shaft, and means whereby actuation of a power drive key releases said clutch.

8. In combination with a tuning element of a radio set, a rotating drive shaft having driving connection with the tuning element, a power drive for said drive shaft, a manual drive for said drive shaft, keys for putting said power drive in operation and selectively stopping said drive at predetermined points, a clutch connecting the manual drive to .the drive shaft, means whereby actuation of a power drive key releases said clutch, and means whereby rotation of the manual drive engages said clutch.

9. In combination with a tuning element of a radio set, a rotating drive shaft having driving connection with the tuning element, a power drive for said drive shaft, a manual drive for said drive shaft, keys for putting said power drive in operation and selectively stopping said drive at predetermined points, a clutch connecting the manual drive to the drive shaft, means whereby actuation of a power drive key releases said clutch, means whereby rotation of the manual drive engages said clutch, separate manual drive and power drive pilot lights, switches controlling the circuits to said pilot lights, and means associated with said clutch for actuating said switches.

10. In combination with a tuning element of a radio set, a rotary drive shaft having driving connection with the tuning element, a plurality of adjustable stop means carried by the drive shaft, a manual shaft for rotating the drive shaft, means for collectively clamping and unclamping the stop means to the drive shaft, and a sleeve upon the manual shaft for actuating said clamping means.

11. In combination with a tuning element of a radio set, a rotary drive shaft having driving connection with the tuning element, a plurality of adjustable stop means carried by the drive shaft, a manual shaft for rotating the drive shaft, means for collectively clamping and unclamping the stop means to the drive shaft, and latch means carried by the drive shaft for latching the clamping means in unclamped position.

12. In combination with a tuning element of a radio set, a rotary drive shaft having driving connection with the tuning element, a plurality of adjustable stop means carried by the drive shaft, a manual shaft for rotating the drive shaft, means for collectively clamping and unclamping the stop means to the drive shaft, and a sleeve upon the manual shaft for actuating said clamping means, said sleeve being slidable upon the shaft to move into and out of actuating relationship with the clamping means.

13. In combination with a tuning element of a radio set having an automatic frequency control circuit, a rotating drive shaft having driving connection with the tuning element, a motor drive for said drive shaft, means for selectively starting and stopping the drive motor, switch means operated by said starting and stopping means whereby the automatic frequency control circuit is out of operation when the drive shaft is in motion and in operation when the drive shaft is stopped, a manual drive for the drive shaft, clutch means for connecting the manual drive and the drive shaft, and means whereby the automatic frequency control is put out of operation when the clutch is engaged.

14. In combination with a tuning element of a radio set, a rotating drive shaft having driving connection with the tuning element, supplemental push button controlled tuning mechanism, detent mechanism associated with said push buttons, and mechanical means actuated by rotation of the drive shaft to release said detent mechanism.

15. In combination with a tuning element of a radio set, a manually operable rotating shaft having driving connection with the tuning element, supplemental tuning mechanism comprising push button operated station selecting slides, detents for said slides, and means responsive to manual rotation of the drive shaft to release the detent mechanism.

16. In combination with a tuning element of a radio set, a manually operable rotating shaft having driving connection with the tuning element, supplemental tuning mechanism comprising push button operated station selecting slides, detents for said slides, detent release mechanism comprising an arm extending adjacent the drive shaft, and a star wheel carried by the drive shaft and adapted to engage the detent release arm upon manual rotation of the shaft to release the 10 detent.

ADOLPH E. GERSCH.