US2251476A - Tuning unit for radio receivers - Google Patents

Description

Aug 5, 1941- A. B. WINCHELL TUNING UNIT FOR RADIO RECEIVERS Filed June 11, 1938 2 Sheets-Sheet 1 INVENTUR ATT URNEY Aug 5, 1941. w Nc 2,251,476

TUNING UNIT FOR RADIO RECEIVERS Filed June 11, 1958 2 Sheets-Sheet 2 .9 8 E77 F g 9 l I 4-3 INVENTEIR ARTHUR HWINBHELL ATTORNEY Patented Aug. 5, 1941 UNITED STATES PATENT QFFIQE TUNING UNIT FOR. RADIO RECEIVERS Application June 11, 1938, Serial No. 213,299

18 Claims.

This invention relates to improvements in a station selector or tuning unit for a radio receiving apparatus. The invention pertains more particularly to a mechanical mechanism having a plurality of manually operated control or selector members, the setting of any one of which will operate a variable condenser unit to tune the radio receiving set to the frequency of a corresponding one of a plurality of pre-selected broadcasting stations without the usual necessity of more or less critically adjusting the main tuning control of the receiving set, which conventionally includes a tuning knob and a dial associated with ganged variable condensers.

The main object of this invention is to provide simply and durably constructed mechanical tuning means which may be readily connected with the operating shaft of a variable condenser, or a plurality of such condensers of a radio receiving set, and which is provided with a plurality of manually operated selector means, each of which is arranged for setting the condenser or condensers for a corresponding one of a selected group of broadcasting stations.

A more specific object of the invention is to provide a multiple control tuning unit for operating a variable condenser which is constructed so that the maximum movement of the condenser may be produced by a relatively small amount of movement of any one of a plurality of manually operated selector members.

'Another object of the invention is to provide a tuning unit of the above mentioned class having the manually operated selectors provided with relatively movable selector elements which may be adjusted at any time to change the setting of the variable condenser produced thereby,

that the selector elements may be quickly and, easily adjusted to produce a desired setting of the condensers associated with the tuning dial.

Other objects and advantages of my invention will be apparent from the following description taken in conjunction with the accompanying drawings, in which:

Figure 1 is a top plan of a tuning unit embodying the various features of this invention, portions of the unit being shown broken away and in section, and the drive member or shaft thereof being illustrated connected with the shaft of a variable condenser.

Figure 2 is a transverse sectional view taken in the plane of the line 2-2, Figure l, illustrating a manually operated selector member in the normal or outer inoperative position.

Figure 3 is a transverse sectional view taken on line 3-3, Figure 1, and illustrating a manually operated selector member in an intermediate position.

Figure 4 is a transverse sectional view similar to Figure 3, illustrating the manually operated selector member in the inner or operative position.

Figure 5 is a detail transverse sectional view taken substantially on the line 5-5, Figure 6, illustrating an inner portion of the toggle mechanism for operatively connecting the manually operated selector members with the drive shaft in the intermediate position illustrated in Figure 3.

Figure 6 is a detail vertical sectional view through the toggle mechanism positioned at one end of the tuning unit taken substantially on line 6-6, Figure 3.

Figure 7 is a detail vertical sectional view taken on line 1-4, Figure 3.

Figure 8 is a transverse sectional view similar to Figure 3, illustrating a modified form of linkage mechanism and is taken substantially on line 88, Figure 9.

Figure 9 is a detail vertical sectional view taken on the line 99, Figure 8.

Figure 10 is a detail sectional view similar to Figure 8 taken substantially on line llll9, Figure 11, and illustrates a further modification of the linkage structure.

Figure 11 is a longitudinal vertical sectional view taken substantially in the plane of the line ll-ll, Figure 10, the central portion of the frame and selector mechanism being broken away.

My novel tuning unit, as illustrated in Figures 1 to 7, inclusive, of the drawings, comprises a substantially rectangular frame H3 adapted to be supportably connected in any suitable manner to the chassis of a radio receiving apparatus. This frame comprises a front plate II, a back plate I2 and two end plates l3. Journaled in the frame Ill, in inward spaced substantially parallel relation to the rear plate I2, is a drive shaft l5 which has the ends thereof extending beyond the side plates I 3 of the frame and adapted to be connected in any suitable manner with a variab e condenser, as indicated at C, Figure 1.

connected thereto at one end by a suitable flexible coupling or other conventional means, whereby rotation of the drive shaft will produce a corresponding rotation of the condenser shaft S and the rotor plates R connected therewith. The end of the drive shaft l5 opposite the condenser C is shown projecting a short distance beyond the adjacent end of the frame l0 and may be connected in any suitable manner to the usual tuning knob and dial spindle of the receiving set whereby said shaft may be manually operated in the conventional manner for adjusting the condenser C during the tuning operation.

Mounted in the frame I0 is a plurality of, in this instance six, manually operated selector or control members H which extend transversely through the frame ID in a substantially horizontal plane beneath the drive shaft .|'5, as illustrated more particularly in Figure 2. Each of these selector members comprises a push rod 2| having the forward portion |8 thereof reduced in diameter and slidably and rotatably received in a corresponding aperture l9 formed inthe front plate II of the frame I0. Each of these portions I8 of the push bars is adapted to extend beyond the front plate II and through the front panel of the radio receiver cabinet into a convenient position to be manually operated from the exterior of said cabinet. A pushbutton 20 may, as shown, be secured to the forward end of each push rod 2| to provide a convenient finger piece by which the rod may be rotated as well as pushed axially for a purpose which will hereinafter be explained.

Each of the push rods 2| has the forward end thereof provided with a transversely disposed slot 22 adapted to receive a screw driver or other implement by which the rod may be rotated. These rods may, as shown in Figures 1 and 2, terminate a short distance inside the push button connected therewith and each push button is provided with a slot or recess 23 in the outer end thereof in registration with the rod slot 22 to allow the screw driver to engage in the latter slot. Each rod 2| is provided with a right-hand screw-thread 24 formed on the portion thereof adjacent the portion l8 and a left-hand screwthread 25 formed on an intermediate portion thereof adjacent the threads 24, the latter screw having the same number of threads per inch as the screw-threads 24. The rear end portion 26 of each rod 2| is shown slightly reduced indiameter and extended through a suitable aperture 21 formed in the rear plate i2 for both rotary and sliding movement with respect tosaid plate.

Mountedrupon the reduced portion 25 of each rod 2| is a compressionlspring 28 which has one end thereof arranged in engagement with the inner face of the rear plate I2 and the other end arranged in contactwith a washer 29 mounted on the reduced portion 26 of the rodin contact with a shoulder 30 formed at the junction of the reduced portion 26 and the screw-threaded portion 25 of said rod.

Mounted upon each rod 2| is a pair of actuating members 32 and 33, one of which has screw-threaded engagement with the screwthread 24 and the other actuating member has screw-threaded engagement with the left-hand screw-threads 25. Each of these actuating members is formed from a substantially flat bar provided with a tail piece 32 or 33', respectively. These tail pieces are arranged side by side and extend through a suitable aperture l2 provided in the rear plate i2 at one side of the aperture 21 for the push rod end 26, as illustrated in Figure 1. The forward end of each actuating member 32 is provided with a portion 34 which extends laterally from the portion 32 thereof and which is provided with a screw-threaded aperture 34 receiving the portion 24 of the corresponding rod 2|. Each bar 32 is also provided with a pendent portion or head 35 which extends downwardly therefrom adjacent the transverse portion 34 to a position substantially in the plane of the lower side of the frame If].

Each of the other actuating members or bars 33 is provided with a laterally disposed portion 33, intermediate the ends thereof, which is provided with a screw-threaded aperture and which receives the screw-threaded portion 25 of the corresponding rod therein. I Each of the bars or actuating members 33 is provided with an extension 31 which projects forwardly from the lateral portion 36 at the side thereof opposite the portion 33 and in substantially parallel relation therewith. The forward end of the portion 31 is provided with an upwardly extending portion or head 38 which terminates in substantially the horizontal plane of the upper face of the frame ID, as illustrated in Figures 2, 3 and 4.

It will now be observed that the heads 35 and 38 for each reciprocating rod 2! are arranged at opposite sides of said rod and that these heads will be moved in reverse directions with respect to each other and to the rod as said rod is rotated in one direction or the other due to the screw-threaded engagement of the bars 32 and 33 with the respective right-hand and lefthand screw- threads 24 and 25 provided on the rod. Also, it will be seen that, due to this arrangement, the head 38 may be moved by rotation of the rod 2| connected therewith from a position in front of the head 35 to a position at the rear of said head, as desired. In order that the push rod 2| may not be accidentally rotated by objects coming in contact with the forward exposed ends thereof or with the push buttons 20, an appreciable amount of friction is maintained between the screw-threads onthe rods and those on the selector bars by bending the transverse portions of at least one of the selector bars as the bars 32 so that said portions Will be normally maintained at a slight angle to the normal position thereof with respect to the push rods 2| associated therewith.

It will now be understood that when the rods 2| are moved longitudinally with respect to the frame |0 against the action of the corresponding springs 28 by pressure exerted upon the outer ends of the push rods 2|, the actuating members 32 and 33 and the heads 35 and 38 associated therewith Will also be moved in unison with said rods. This movement of the bars 32 and 33 is for the purpose of bringing the heads 35 and 38 into cooperative engagement with a suitable linkage mechanism associated with the drive shaft |5- for rotating said shaft.

This linkage mechanism, as 40, comprises a pair of rock arms 4| mounted upon the drive shaft l5 adjacent the side plates l3 of the frame NJ, as shown in Figure 1. Each of these arms 4| is a substantially U-shaped member which is clamped to the shaft |5 by a screw 42 mounted in the' transverse portion of the arm. The outer or free ends of each rock arm 4| is connected by a pair of links 43 with corresponding ends of a pair of rock levers 44 and 45 which are rotatably mounted upon a pivotal post or stud 46. As shown in Figure 1, there are two of the pivotal members 45 arranged one at either end of the frame l0. Each of these members 46 is provided with a screw-threaded portion 41 which extends through a suitable aperture formed in the adjacent side plate l3 of the frame and is clamped to said side plate by a nut 48 mounted on said screwthreaded portion.

The inner end of each pivotal member 46 is reduced somewhat in diameter, as at 41, and rotatably supports the adjacent rock levers 44 and 45 thereon. These levers are maintained in spaced relation to each other by a suitable spacing sleeve 49 mounted on the portion 41 of the corresponding stud 46 between the levers 44 and 45, as illustrated in Figure 6. The pivotal studs 45 are connected with theframe ID in coaxial relation with each other and so as to lie in substantially the horizontal plane of the push rods 2| a short distance infront of the vertical plane passing through the drive shaft l5. The inner positioned rock levers 45, as shown, are construoted alike and extend. some distance above the pivotal studs 46 and. are tied together at their upper ends by a suitable tie-rod 50 which extends longitudinally withinthe frame H] in a horizontal plane above the push rods 2| and in the path of movement of the actuating heads 38. Similarly, the outer positioned rock levers 44 are constructed alike and are connected with each other by a tie-rod 5| which extends in substantially a horizontal plane longitudinally within the frame below the push rods -2| and in the path of movement of actuating heads 35. The tie-rod extends through clearance openings 45' provided in the levers 45.

The distances from the common axis of rotation of the levers 44 and 45 to the tie-rods 58 and 5| are substantially equal. Furthermore, the distances from the common axis of rotation of the levers 44 and 45 to the pivotal connections 53 between these levers and the links 43 are substantially equal. 'It therefore follows that for each degree of movement of the tie-rods 50 and 5| about the axes of the pivotal studs 46, a uniform degree of movement of the pivots 53 and; therefore, of the arms 4| will be produced.

In the construction shown in the drawings, the distances from the common axis of swinging movement of the levers 44 and 45 to the pivots 53 are substantially twice the distances from said axis to the axes of the tie-rods 50 and 5|, while the distance from the axis of the drive shaft |5 to the pivot connection, as 54, of the arms 4| with the links 43 is slightly less than the distance from said common axis of rotation of the levers 44 and 45 to the tie-rods58 and 5| so that the degree of rotation of the shaft l5 produced by engagement of the heads 35 and 38 with the tierods 5| and as each push rod 2| is moved inwardly against the action of the corresponding spring 28. The tie-rod which is nearest its actuating head 35 or 38 when said heads are in their normal outermost position will, of course, be engaged first by said head and be swung rearwardly thereby. This rearward movement of one of the tie-rods will effect a corresponding forward swinging movement of the other tie-rod due to the connection of said rods with each other, provided by levers 44 and 45, links 43 and arms 4|. This forward swinging movement of one of the rods 59 or 5| will continue until said rod is engaged by its actuating head 35 or 38, whereupon the rods and heads will be held against further movement in their respective directions. It therefore follows that the rock levers 44 and 45, arms 4| and the drive shaft |5 will be moved to a predetermined position upon each inward stroke of an actuating member I? and the direction of rotation of the shaft |5 will depend upon which of the two tie-rods of the linkage mechanism is first engaged by an actuating head.

When it is desired to adjust or set the tuning unit so that the manipulation of a predetermined one of the reciprocating control or selector members ll will set the variable condenser C to the frequency of a selected broadcasting station, the heads 35 and 38 of that selector member H are moved inwardly by pressure exerted upon the outer end of the corresponding push bar 2| until both heads contact with the tie-rods 50 and 5| As the heads 35 and 38 thus engage the tierods 50 and 5| the frequency to which the condenser is then tuned may be readily determined by observing the setting of the usual tuning dial associated therewith. If the tuning dial indicates that the condenser is not tuned to the frequency of the station selected, the selector member I! is adjusted to properly set the condenser in the following manner: The push rod 2| is rotated by means of the push button 28 or a screw driver engaging in the slot 22, While the heads 35 and 38 are being firmly maintained against the tierods, in a direction to move said heads toward or from each other, depending upon the direction it is desired to rotate the condenser shaft S for tuning the condenser to the desired station. This movement of the heads 35 and 38 toward or from each other will produce a corresponding rotation of the levers 44 and 45 about the axes of the pivotal studs 45, and this rotation of the levers will produce a corresponding movement of the rock arms 4| and shaft l5.

It will be understood that rotation of shaft l5 will produce a corresponding rotation of condenser C and also of the tuning dial associated with said condenser and shaft. It follows, therefore, that the push rod 2! may be rotated in the proper direction until the tuning dial indicates that the condenser is tuned to the frequency of the broadcasting station selected. The push rod may then be released whereupon the spring 28 will return said rod to its normal forwardmost position.

After the first selector member IT has been thus adjusted to tune the condenser to a given station, a second one of the selector members may be adjusted in a similar manner for tuning the condenser to a second station. In like manner, the remaining selector members i! may be adjusted for tuning the condenser to a corresponding one of a group of selected stations. After the selector members have all been properly adjusted, it will be obvious that the receiving set may be quickly and easily tuned to the frequency of any one of said group of selected stations by merely pressing inwardly on the proper push bar 2 I.

To explain more explicitly, let it be assumed that the heads 35 and 38 of the selector member I1 to be actuated are positioned as illustrated in Figure 2. It will be observed that as the push rod 2| is moved inwardly against the action of the spring 28, the head 38, being normally nearer to the tie-rod 50 than the head 35 to the tierod 5|, will engage the tie-rod 50 prior to the engagement of the head 35 with the tie-rod 5|. In other words, the selector member |1 will be in the position illustrated in Figure 3 when the head 38 contacts the tie-rod 50. As the selector member is moved inwardly to a greater distance, the head 38 will rock the levers 45 about the axes of the studs 46 in adirection to move the rear ends of said levers connected with the links 43 downwardly and thereby produce a corresponding downward movement of the rock arms 4|.

This downward movement of the arms 4| will produce a corresponding downward movement of the rear ends of the levers 44 due to the connection of said levers with the arms 4| by links 43. This downward rocking movement of the levers 44 will produce movement of the tie-rod 5| connected therewith toward the front side of the frame I so that the head 35 and tie-rod will be moved in directions toward each other until the head 35 engages the rod 5 I, at which period in the operation of the selector member the heads 35 and 38 and the linkage mechanism will be in the position illustrated in Figure 4. This rocking movement of the levers 44 and 45 will, of course, produce a corresponding rotation of the shaft I5 and the rotor plates R of the condenser C connected with said shaft. As the push bar 2| is released, the spring 28 connected with the corresponding control member will return the push rod 2| associated therewith to its normal outermost or inoperative positions, while the condenser will remain in the set position.

In order to tune the set to another selected station of the group, it is only necessary to push inwardly on the corresponding control member I1 to bring the heads 35 and 38 thereof into engagement with the tie-rods 50 and 5|. When both of said heads engage said tie-rods, the condenser will be properly adjusted to the frequency of the station selected. It will be understood that the push rods 2|, when in their outermost inoperative positions, will maintain the selector heads 35 and 38 out of the path of movement of tie-rods 5'0 and 5| so that said rods are free to be actuated by the heads associated with any one of the selector members H for adjusting the condenser. Also the condenser may be adjusted by the conventionally constructed tuning control of the receiving set when the selector heads are in their operative positions at one side of the path of movement of the tie-rods 50 and 5|.

The modified structure shown in Figures 8 and 9 is very similar in construction and operation to that shown in Figures 1 to 7, inclusive. This structure is adapted to actuate a drive shaft, as l5, which is positioned either above or below the supporting frame I0. The drive shaft I5, in this instance, is shown as being positioned above the frame III while the levers, as 44 and 45 and the links 43 and arm 4|, are of such a length and form as to permit them to readily rotate the shaft I5 upon engagement of any one of the manually operated selector or control members I1 with the tie-rods 50 and 5|. In the structure shown in these figures, there is provided a set of levers 44' and 45' at each end of the frame ID. The levers 45 of each pair are constructed substantially alike except that one is a right-hand lever and the other is a left-hand lever. Likewise, the levers 44 of each pair are constructed substantially alike except that one is made a right-hand leverand the other a lefthand lever. The rock levers 44' and 45 are of substantially goose-neck construction, as illustrated in Figure 8, so as to provide sufficient movement of the levers to produce a maximum rotation of the shaft I5 without their coming into contact with said shaft. In this instance, the drive shaft I5 is supported by any suitable means exteriorly of the frame I0, such as indicated at 55, Figure 9, which may comprise a portion of the housing or frame supporting the variable condenser to which the shaft I5 is connected.

In Figures 10 and 11, the linkage mechanism connecting the tie-rods 50 and 5| with the drive shaft I5 is adapted more particularly for operating the shaft I5 when said shaft is positioned at one side of the frame I0, either above or below said frame, and in substantially parallel relation with the push rods 2| instead of transversely of said push rods as in the structures shown in Figures 1 and 8. In the structure shown in Figures 10 and 11, the drive shaft I5 may be supported at one side of the frame In by any suitable means, as by the condenser frame indicated at 55, secured to the chassis of the radio receiving set. As shown more particularly in Figure 10, the rock levers 5B and 51 connected with the tie-rods 50 and 5| positioned at one end of the frame I I] are substantially L-shaped members which are pivotally mounted upon the pivotal post or stud 41 carried by the frame I0. The shorter legs, as 56' and 51 of the levers 56 and 51, extend in opposite directions from the pivotal stud 41 and support adjacent ends of the tierods 50 and 5| respectively. The opposite ends of the tie-rods 50 and 5| are similarly supported by a pair of rock levers 58 rotatably mounted upon a pivotal stud 41 positioned in the opposite end of the frame In from the levers 5B and 51. These levers 58 are relatively short members which function to rotatably support the adjacent ends of the tie-rods 50 and 5| only and are not connected, in this instance, directly with the drive shaft I5. The tie-rods 50 and 5| are preferably fixedly connected with the levers 56, 51 and 58 to provide a relatively rigid operating structure, that is, one which will function without flexing, for producing the required movement of shaft I5 irrespective of the particular selector member I1 by which said operating structure is actuated.

The drive shaft I5, in this instance, is provided with a single rock arm 4| constructed and secured to the shaft I5 in the manner described above and shown in Figures 1, 3, 4 and 5 of the drawings. The outer ends of the arm 4| are pivotally connected with links 43' which, in turn, are pivotally connected to rock levers 59 and 60, as shown in Figures 10 and 11. These levers 59 and 60, as shown, are pivotally connected intermediate their ends, as at 6|, to the supporting member 55 at one side of the shaft I5 to rock about a common axis extending in spaced substantially parallel relation with shaft i5. The ends of the levers 59 and 60, at the opposite side of the pivot -6l to that of the links 43, are operatively connected with the rock 1evers 56 and 51, respectively, by tie- rods 62 and 63.

It will now be observed that inasmuch as the rock levers 59 and 60 rotate about an axis extending substantially parallel with the shaft l5 and in substantially right angular relation with the axis of rotation of the levers 56 and 57, the shaft l5 will be rotated in one direction or the other by the engagement of the heads 35 and 38 with the tie-rods 50 and 5|, depending upon which of the heads is first to engage a tierod.

Furthermore, it will be noted that in each of the three different structures illustrated in the drawings, there is a double linkage mechanism connecting the actuating elements or tie-rods 5i! and 5| with the adjacent portion of the drive I shaft l5, one of these linkage mechanisms being adapted when operated by its respective actuating element, to move the drive shaft I5 in one or a clockwise direction and the other linkage mechanism being adapted, when operated by its respective actuating element, to move the drive shaft I5 in the opposite or counterclockwise direction. This arrangement of the linkage mechanisms provides a structure which will accurately position the drive shaft I5 upon each inward movement of a selector member I! without the necessity of constructing the linkage mechanism with a high degree of precision. Also, this structure will function efficaciously over an extended period of time, even though lost motion is introduced therein as a result of wear taking place at the joints or pivotal connections between the levers and links;

While I have shown and particularly described the preferred embodiments of my invention, I do not wish to be limited to the exact construction shown as various changes, both in the form and the relation of parts thereof, may readily be made without departing from the spirit of the invention as set forth in the appended claims.

I claim:

1. A tuning unit for a radio receiver comprising a drive shaft adapted to be operatively connected to the shaft of a variable condenser, a reciprocating selector rod mounted for movement at one side of the drive shaft, means for actuating said shaft including a linkage mechanism connected therewith and having a pair of operating members arranged at opposite sides of the selector rod, spaced actuating elements mounted on said selector rod movable into and out of operative engagement with said operating members during the reciprocation of said rod, and manually operated means for actuating the selector rod.

2; A tuning unit as in claim 1 wherein the actuating elements are adjustably connected with the selector rod for movement with respect to each other whereby the degree of movement of the linkage mechanism produced by the engagement of said elements with the operating members may be varied.

3. A tuning unit as in claim 1 having spring means connected with the selector rod for yieldingly maintaining the actuating elements out of engagement with said operating members.

4. A mechanical tuning unit for a radio receiver comprising a plurality of manually operated selector members, a drive member mounted in spaced relation to said selector members, an

actuating mechanism connected to the drive member, said mechanism having a pair of operating members therefor common to all of said selector members and arranged at opposite sides of said selector members, each of said selector members having spaced actuating elements movable into and out of operative engagement with said operating members during the operation of said selector members, and means for adjusting the actuating elements toward and from each other to cause a variation in the degree of movement of the operating members and therefore of the drive member produced thereby.

5. A tuning unit for a radio receiver comprising a frame, a plurality of selector rods connected with said frame for reciprocating movement With respect to each other, a drive shaft adapted to be connected with the shaft of a variable condenser rotatably connected with said frame at one side of said selector rods, actuating means for operatively connecting the selector rods with said drive shaft including a pair of linkage mechanisms rotatably connected to the frame to rock about a fixed axis and connected to said drive shaft, a pair of tie-rods connecting said linkage mechanisms arranged at opposite sides of said axis of rotation of the linkage mechanisms, a pair of actuating elements on each of said selector rods movable into and out of engagement with a respective one of said tie-rods during the reciprocating movement thereof for actuating the linkage mechanisms, and manually operated means for actuating said selector rods.

6. A tuning unit as in claim 5 wherein the selector rods are rotatably mounted and have right and left screw-threaded engagement with said actuating elements whereby rotation of each selector rod will produce relative movement of the actuating elements connected therewith toward or from each other for varying the degree of movement of the tie-rods produced thereby during. the reciprocation of said selector rod.

7. A tuning unit as in claim 5 wherein the selector rods are rotatably mounted and have right and left screw-threaded engagement with said actuating elements whereby rotation of each selector rod will produce relative movement of said actuating elements connected therewith toward or from each other for varying the degree of movement of the tie-rods produced thereby during the reciprocation of said selector rod, and spring means interposed between the selector rods and said frame for yieldingly urging the rods in one direction to maintain the actuating elements out of engagement with the tie-rods.

8. A tuning unit for a radio receiver comprising a frame, a plurality of reciprocative selector members mounted in said frame in spaced substantially parallel relation to each other, a drive shaft adapted to be operatively connected with the shaft of a variable condenser rotatably mounted in said frame at one side of and extending transversely to said selector members, a plurality of pairs of actuating elements, one pair for each selector member, the elements of each pair being arranged in spaced relation to each other, rock members pivotally connected with said frame to swing about an axis extending substantially normal to the axes of reciprocation of the selector members, a, pair of operating members connected with said rock members at opposite sides of the axis of rotation thereof and arranged in the path of movement of each pan of actuating elements to be alternately engaged thereby so that the rock members will be rocked in one direction or the other depending upon which of the operating members is first engaged by an actuating element, and means operatively connecting the rock members to said drive shaft,

9. In a tuning unit for a radio receiving apparatus, in combination, a frame, a selector rod supported by said frame to extend forwardly therefrom and for both longitudinal and rotary movements with respect thereto, a condenser drive shaft rotatably supported by the frame, a pair of selector elements slidably supported by the frame and having screw-threaded connection with the selector rod to be reciprocated by the rod in unison therewith during said longitudinal movement of said rod and to be moved relative to the rod toward or from each other during said rotary movement of said rod, a pair of operating elements arranged at one and the same side of the selector elements in the path of movement thereof, means pivotally connecting the operating elements to the frame So that said operating elements may swing about a fixed axis extending substantially midway between said operating elements and transversely to the axis of movement of the selector rod, means associated with said pivotal means for operatively connecting the operating elements to the drive shaft, said selector rod having a fingerpiece connected with the forward end thereof by which said rod may be both moved longitudinally to bring the selector elements into engagement with the operating elements and rotated during said engagement of said elements with each other to alter the relative position of the selector elements and of the position of the operating elements produced thereby.

10. In a tuning unit for a radio receiving apparatus, in combination, a frame, a selector rod supported by said frame to extend forwardly therefrom and for both longitudinal and rotary movements with respect thereto, a drive shaft rotatably supported by the frame adapted to be connected with a variable condenser, means perably connecting the selector rod with the shaft comprising a pair of selector elements slidably supported by the frame and having screwthreaded engagement with said selector rod to be reciprocated by said rod in unison therewith during said-longitudinal movement of the rod and to be moved relative to the rod toward or from each other during said rotary movement of said rod, an operating mechanism connected to the shaft and including a pair of operating elements, each of said operating elements being arranged at the rear side of a corresponding one of the selector elements in the path of movement thereof, and means including a pivotal member arranged intermediate the operating elements for rotatably connecting said operating elements to the frame, the forward end of said selector rod being provided with a tool engaging means by which said rod may be both moved rearwardly to bring the selector elements into engagement with the operating elements and rotated during said engagement of said elements with each other to alter the position of the selector elements and of the position of the operating elements produced thereby.

11. A mechanical tuning unit for a radio re ceiver comprising a frame, a manually operated selector rod supported by said frame for longitudinal reciprocative movement with respect to said frame, a rotatable drive shaft adapted to be connected to the shaft of a variable condenser, said shaft being mounted at one side of the frame in spaced relation thereto, means operably connecting the selector rod to the drive shaft whereby reciprocative movement of said rod will produce rotary movement of said shaft including a pair of operating elements mounted at opposite sides of the selector rod to swing about a common axis, means actuated by the selector rod for swinging the operating'elements to predetermined positions in their path of movement, and a linkage mechanism operatively connecting the operating elements with said shaft.

' 12. A tuning unit as in claim 11 wherein the drive shaft is arranged to extend in substantially parallel relation with the selector rod, and the linkage mechanism includes a rock lever having anfaxis of swinging movement extending substantially parallel with the axis of rotation of the drive shaft in fixed relation therewith.

13. In a tuning unit for radio receiving apparatus, in combination, a frame, a selector rod supported by said frame for longitudinal movement with respect thereto, a drive shaft supported by the frame in spaced relation to said selector rod and drive members, actuating means for operatively connecting the selector rod with said drive shaft including a pair of drive members connected with said selector rod to move therewith and spaced from each other longitudinally of said rod, a pair of driven elements one for each drive member, said driven elements being pivotally connected to the frame to rock about a common axis, and a pair of linkage mechanisms connecting the drive shaft with the driven elements respectively, one of said driven elements and the linkage mechanism therefor being arranged to rotate the drive shaft in one direction and the other driven elements and the linkage mechanism associated therewith being adapted to rotate the drive shaft in the opposite direction when said driven elements are operated by their respective drive members.

14. In anautomatic tuning device, a member movable on an axis for tuning purposes and means to move said member to a predetermined position, said last mentioned means comprising a manually translatable element and a pair of positioning means on said element for moving said first mentioned means and for fixing it in position by contacting it on each side of its axis, said manually translatable element bearing means for changing the position of said positioning means and accessible at an end of said manually translatable element.

15. In a device of the character described, means pivoted on its axis, a plunger longitudinally movable in a direction transverse to and through said axis, longitudinally movable means on said plunger for contacting said pivoted member respectively on each side of its said axis, and means on said plunger for moving said longitudinally movable means substantially equally and in opposite directions.

16. In a device of the character described, means pivoted on its axis, a plunger longitudinally movable in a direction transverse to and through said axis, longitudinally movable means on said plunger for contacting said pivoted member respectively on eachside of its said axis, and means on said plunger for moving said longitudinallymovable means substantially equally and in oppositedirections, said last mentioned longitudinally movable means comprising a shaft having threaded engagement with said longitudinally movable means.

17; In a device of the character described, means pivoted on its axis, a plunger longitudinally movable in a direction transverse to and through said axis, longitudinally movable means on said plunger for contacting said pivoted member respectively on each side of its said axis, and means on said plunger for moving said means substantially equally and in opposite directions, said last mentioned means comprising a shaft having threaded engagement with said longitudinally movable means, an end of said shaft constituting a means whereby said plunger may be moved.

18. In a device of the character described, means pivoted on an axis and means for moving said pivoted means, said last mentioned means comprising a plunger, adjustable positioning means on said plunger for two-way location of said pivoted means and comprising a pair of abutments each adapted to act upon said pivoted means on a different side of its axis, and a common means for moving said plunger and for varying the position of said adjustable positioning means.

ARTHUR B. WINCHELL.

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