US2189282A - Receiver tuning control - Google Patents

Description

Feb. 6, 1940.

D. E. FOSTER RECEIVER TUNING CONTROL Filed Dec. 23, 1935 6 Sheets-Sheet 1 @sns/e www ATTORN EY Feb. 6, 1940. D. E. FOSTER 2,189,282

RECEIVER TUNING CONTROL Filed Deo. 23, 1935 6 Sheets-Sheet 2 INVENTOR DUDLEY E. FOSTER AT`TORNEY Feb. 6, D, E, FOSTER RECEIVER TUNING CONTROL Filed neo. 23, 1935 6 Sheets-Sheet 3 lNvENToR DZ/LEY E. FOSTER BY 7M ww ArToRNEY v Feb. 6, 1940. D. E. Pos1-ER 2,189,282

RECEIVER TUNING CONTROL Filed Dec. 23, 1935 6 Sheets-Sheet 4 INVENTOR DUDLEY E. FOSTER BY vw@ ATTO R N EY Feb. 6, 1940. D. E. FOSTER I RECEIVER TUNING CONTROL 6 Sheets-Sheet 5 Filed Dec. 23, 1935 foo Feb. 6, 1940. D. E. FOSTER RECEIVER TUNING CONTROL Filed Dec. 23, 1935 6 Sheets-Sheet 6 m 2 mw n i mf m l WF.. v` O y 2 o m w. M

'Patented Feb. 6, 1940 UNITED- STATES iaii'itrzlvi' OFFICE 2,139,282 o RECEIVER TUNING' coN'rRoL` Dudley E. Foster, Orange, N. J.,assignorvto Radio i m.

Corporation of America, a corporation of `Delai Ware x Application December 23, 1935,` Serial No; 55,'4749 24 claims. (c1. 250%20) u d i u.:

. ,My `present invention'relates` to radio receiver `tuners, and more particularly to novel and imf "proved arrangements for accurately adjusting, in a simplewnianner, the tuning deviceof a radio receiver of the superheterodynetype.`

r.In the past,` radio receivers Ahave been tuned j' by variationcf the capacity of the receiving cir-` cuit'throug'h the medium of a reduction gear tun- `ing knob. This hasbeen necessary because of 'the high selectivity provided by modern broadx o `'cast receivers, and particularly receivers of the superheterodyne type. i Moreover, the addition of automatic volume `control "to modern receivers `has resulted in rendering the tuning `compara- -.tive difficult in spiteofthe reduction ratio of the mechanical drivebetween the-tuning device and by the use of auxiliary devices. Accordingly, it"l will be seen that the reduction. ratio tuning mech,-`

anism, necessitated by modern receiverselectivy ity, not only results-in slow and tedious tuning operation, but also gives rise to inaccuracies in "such tuning. j

Automatic frequency control (AFC hereinafter) for a superheterodyne receiver has been previously known; this control tends to automatically center the received signal in the I. F.

` (intermediate frequency) reception band. However, the tuning `operation is greatlysirnplied by the `utilization of the AFC. Therefore, advantage may be taken of thisqfact .to simplify the tuning mechanism for the purpose of obtainingease and rapidity yo tuning.

Accordingly;` it may bestated that itisone of the primary objects of my present invention to take full advantage of `the utilization of AFC in a receiver of the superheterodyne type, and` to pro- @vide a manually adjustable tuning mechanism whichl enables the userrapidly towchange 4the setting of the tuning device to any point required for reception of a desired'signal.

Another important object .ci the invention is` to `provide an 'instantaneous selector device in mechanicalassociation with the tuning condenserY mechanism, and wherein the selector may )be adjusted to y positions corresponding to.' predetermined station settings ofthe tuning condenser;

an'AFC network inthe receiver functioning to "9. remove the necessity for mechanical accuracy o imposed by modern receiver selectivity.

In practical operationvthe employment'oi' the v e uf maticlvolume control is utilized. `1 l AFC network gives rise toa so-called carry over diculty. Since the AFC tends to keepjthe local oscillator frequency constant over an ap preciable range of variation of the tuning con-o` denser, if a signal is brought Within the recepf5 tion band the AFC `functionsfto maintain the oscillator frequency such that this signal only givesfthe correct intermediate frequency. Hence,v

it will-be' seen that inturiing a receiver equipped `with AFC, the station signal ilrst operating the ft/10 -control vvill 4be held after the tuning condenser position corresponding to` an adjacent signal `channel has been passed over. This carry overv action; in brief, arisesby-virtue of the AFC causing a shift in the local oscillatorfirequency to`-15 l 'such an extent that one 'received carrierwillcontinue the operation of the AFC to the `exclusion l of'one or more adjacent carriers.

Further'investigation connectedwith the 4ern- `bodimentof 'AFC ina superheterodyne receiveniBo and'thesimplificationof` the tuning operation,

yhas resulted in an altered conclusion 'Withrelspect tothe correlation' of the tuning mechanism and the functioning of the AFC network. Ithas been found that in order definitely to ensure rer-25.25 1.,-,

ception of'desired stations, the AFC'mustfbe ren-j` deredinoperative during the portion of the tuning operation just priorto the tuning condenser setting atQWhichl the desiredfsignal Would be ob-v l, `rtained 'with' the AFC in inoperative condition-e30 When, howeventhe variable'condenser has been adjusted within the channel of the desired station;V the AFC is again .rendered operative and i completes 4the tuning operation. Such a corref" lation ofAFC operation'and `tuning adjustmenta not' only` results in aycomplete simplication of the tuning operation, and accuracy of station selec'ting, but further gives rise to quie tuning.

between adjacent signal channels Where auto- It may, therefore, vloe stated that it' is another important objectof my present invention to pro- 'vide in a superheterodynereceiver equipped with, .o

AFC and a station selector dial mechanism which is rmechanically coupledwith the .tuning con-:A5`

denser device, a control switch located at a xed reference point with respect to the selector dial,

and` which functions toi render inoperative the f AFC during a relativelysmall portion ofl the dial `rotation in order to eliminate `the tendency ofmio the AFC to cause a shift inthe local oscillator o vfrequency to an extent that one carrier Will cause response to the `exclusion of other carriers.

Still another object offrny present invention is o to provide a simplified and accurate station se-$55.

lector device for a radio receiver of the superheterodyne type, and which receiver is equipped with AFC of the local oscillator; the station selector generically comprising a rotatable dial provided with a series of spaced openings; the openings corresponding to different desired -stations; and a shiftable-stop element being positioned in such relation with respect to the selector dial that the receiver tuning device has its motion of adjustment arrested at the same location regardless of Whether the rotation of the dial is clockwise or counter-clockwise.

Another object of this invention isV to provide a radio receiver of the superheterodyne type with an AFC network, as well as a station selector dial for simply and accurately adjusting the tuning condensers of the receiver; the dial being provided with adjustable spaced station buttons provided with elements adapted to mechanically co operate with a dial rotation stop member in order to limit the rotation of the Vdial in accordance` with selected station buttons; and the selector dial being further associated with a control mem- ;ber for the AFC network with the result that the AFC isoperative at all times except when a selected button is adjusted into mechanical cov'operation with the stop mechanism.

And stillj other objects of my present'invention are to improve generally, the simplicity, accuracy trol mechanism, and more especially to provide such mechanisms in superheterodyne receivers las acteristic of my invention are set forth in particy ularity in the appended claims, thevinvention, it-

lself, however, as to both its organization and method of operation will best be understood by reference to the following .descriptionctaken in `connection with the drawings, in which I have in- I dicated various mechanical embodiments whereby my invention maybe carried-into effect..

Fig. 2 is a front view `of the station selector :mechanism, of the type shown in Fig. Las* viewed from the front of the radio receiver operating lpanel, v

Fig. 3 is a partial sectional view of the-'station selector mechanism, taken along line 3 3 of Fig.

2 looking in the direction of the arrows,

vdetailed construction of the modication of 1Fig.6,

Fig. i8 is an 4end view'ofthe selector modification in Fig. 6,

Fig. '9 isafront viewof still another modified formvof selector mechanism,

Fig. 10 is an end view,A partly in section, of the selector'modication of Fig. 9,v

11 is vanother modification, Vviewed from V-Vthe receiver panel, of they type of selector Vrnechyanism yshown in Fig. `9, Y

lFig. 1'2-*i-s an' end view, partly in-section, of the modification vshown in Fig. l1.

`specific AFC network employed therewith, it is believed suflicient for the purposes of this application to point out a typical receiving system which can be utilized in conjunction with the ncvelstation selector mechanism of my present invention. The receiving system shown in Fig. 1 is a conventional representation of the system shown in detail in Fig. 4 of application Serial No. 45,413, filed October 17, 1935 by S. W. Seeley, patented June 21, 1938 as U. S. P. 2,121,103.

Itl will be suicient vfor those skilled in the art, to brieiiy describe the main elements of such a s supe'rheterodyne receiving system which ,is provided with AFC. The usual signal carrier energy collector A, such as a grounded antenna; a radio frequency distribution line; or the conventional collector used on an automobile radio receiver; is coupled to the tunable input lcircuit of :Le receiver. The tunable input circuit usual`y comprises a variable tuning condenser I, and it is to be clearly understood that the first stage of the receiver may be a radio frequency amplier. In order to kpreservesimplicity of disclosure and drawing, `the numeral 2 designates the rst detector.v e

The output circuit 3A of the iirst detector is resona-ted to the operating intermediate frequ'ency. which may have a value, for example. ofy 'to465 k. c. (kilocycles). .The I. F. am-

, plifier has its inputcircuit 5 resonated to they operating I. F. and coupled to the first detector output circuit 3. The I. F. amplifier It is followed by ai double diode tube, as in the 6H6 type tube.

This type of tube is provided with independenty diode electrodes, and the common resonant input circuit l' has one side thereof 'connected to the diode anode 8. while the opposite side of the circuit is connected to the diode anode 9. The

uhigh alternating potential side of the output circuit 6 of the I. F. ampliiier Il is connected through condenser til to the midpoint of the coil 'l' of input circuit l. This midpoint i l is connected to the junction. of resistor portions l2 and I3; one side of resistor i? being connected to the cathode B of the diode ii-SZ and one side of resistor I3 being connected tothe cathode 9' of the diode 9 9.

The condenser i4 is connected between cath @des 8 and 9', and the cathode 9 is grounded.`

The input circuit I is tuned to the operating I. F is reactively coupled to ythe circuit E. as designated by the reference letter M. The audio component of detected I. F. energy is impressed upon one or more audio amplifier stages, followed by a reproducer. through lead I5 and condenser I6. the latter being connected to the junction of resistors l2 and i3. The automatic volume control (AVC) connection i? is employed to apply the direct current voltage component of rectified yI. F. energy to the signal grids of controlled tubes and 1i. The AVC connection il is made tothe junction of resistors l2 and i3, and of course, the

, directcurrent voltage component is transmitted through appropriate lter resistors before being' applied to the gain control grids of the controlled tubes. ,I

The AFC network involves the tunable tank circuit I8 of the local oscillator I9. As is well known the variable lcondenser 2Il in the tank circuit `I8 has` its rotors mechanically uni-con trolled with therotors of the variable tuning condensersj of the tunable signal circuits feeding the rst detector.` The'dottedline 2I represents such mechanical uni-control.. Of course,4 the oscillator I9 is tuned, at any` setting ofthe tun-l is varied' through the operating frequency range,

which may be the broadcast bandl of 500 to 1500 k. c. C l

The locallyproducedoscillations are impressed `on the first detector 2 in any desired manner, as

by impressing them on vthe cathode circuit of the rst detector; Ofcourse, itis not essential to this invention to employ7 separate tubes 2 and I9 for the mixer and oscillator functions. 'A penta- `grid converter of the 2A7 type may be employed, `in any well known manner, `for a composite oscillator-mixer stage.` In any case `there is electrically associated `with the tank circuit I8 a frequency control tube 22. Theconnections between I the plate circuitof tube 22 and tank circuit. I8

are such that a negative across the tank circuit.

Briefly, and without going into capacity is reiiected `a detailed `dis- .cussionof the specific connections between the frequency control 22 and the tank circuit I8, it is pointed out that a resistor 23 and condenser 24 are connected in series across the tank circuit I8.` If the resistance of resistor `2?- is large compared to the" reactance` of condenser 24, currents through this series circuit will be substantially' in l phase with the voltage across the tank circuit I8. l The current passing through the condenser 24 produces avoltage across the condenser which lags the voltage across the tank circuit by substantially 90. `This lagging voltagek is applied to the grid of control tube 22, and the latter` is preferably of the high mu,high plate impedance' type. AItcan then be seen that the plate current, flowing in connection 25 to tube 22 will be substantially 90 ahead of the voltage across the tank circuit I8. The current through the tuning condenser of the tank circuit I8 lags thevoltage across that 4circuit about 90. Thus, any plate current fiowing through' connection 25 to tube 22 actsas though the current owing in the variable tuning condenser has been decreased.

The AFC connection 26 is madev from the control" grid of tube 22, through an appropriate filter resistor, tothe cathode sideofresistor I2. .The mutual conductance of tube 22 isvaried inde `pendence upon the magnitude of the direct current component of the differential rectified I. F. energy. The magnitude and polarity of the po tential at the cathodeside of resistor I2 vdeter` lresonant frequency is applied, are added vecl torially, the absolute magnitude of the resultant ondary circuits I5` and] are so related that two vector sum. potentials of thev primary and sec- 5 'ondary voltages may be realized. The magnitude and the polarity ofthe potential at point 4I) determines the magnitude of the effective inductance reected across tank circuit I8. Thus,l if the `AFC voltage applied to the grid of` tube 22 is positive (thereby overcoming some of the `initial bias appliedin the cathode circuit of that tube), its mutual conductance is increased. The amount of leading current flowing in connection 25 is thereby increased; which is the same'asl through the lagging current flowing throughthe variable tuning condenser 20 has been decreased. This, in turn, acts asthough that condenser had been decreased .in value `thereby `causing" the tuned frequency of tank circuit I8 to increaseA Assume, now, that `a signal impressed on primary circuit is approaching the I. F. value of `465 k. c., an operating frequency chosen by way of illustratiom but is less than the latter; and also assume that point has a positivepotentialwith respect to ground. Then Vthe frequency departure may be due to a shift in oscillator frequency towards a lower frequency,l or due to tuning the receiver towards the high endof the tuning range. The grid of tube 22 becomes positive, and increases` the gain of the tube. This will result'in an increase in the effective inductance reiiected across tank circuit I8;v and the p frequency of the tank circuit will increase.` In this way the frequency difference between the signal and oscillator circuits automatically is made to increasetowards the desired I; F. value.

A practical difculty encountered in employ- Aing AFC' in `a superheterodyne receiver is -the kproblem of dislodging a strong signal to make i way for a weaker one on a closely adjacent channel, without having the weaker station jump right across the "band toV disappear onthe other side. To overcome this diiculty a switch 3D may be employed. l

'I'he switch S0 functions to ground the bias voltage derived frompoint 40, and rendersthe AFC network inoperative at the will of the opierator.r This offers a means for correlating the 4operation of the AFC network with the tuning 50 operation so as to render the tuning of the receivingl system not' only accurate, 'but highly simplified. `In Fig; 1 there is shown schematiiliary switch 3l which comprises a relatively fixed contact element 32. and a relatively movable contact element `33. The contact 32 is connected by lead 34to the AFC line 26, whereas the `con-` 30 may be mounted in the rear of the receiver `chassis, whereas thesupplementary switch kEll maybe mechanically associated with the selector dial as shown'in Fig. 3. 1 y y The station selector mechanism that is em-f5 l ployed is of the dial type. It generally, comprises a rotatable disc 4H which is provided with a plurality of station selector elements, or ears, 4I.r Each of thesey elements 4I is provided atits outer en@ with sdepressibie button `4in/and ati-f7.0 its inner end with 'a threaded screw member 43. The function of members 43 is to adjust each of the selector elementslll `inany desired radial' position `alongfthe periphery of the dial disc 40. vA groove 44 in thel exposed face of thedal disc `.7.5

yjusting screws 43. This Apermits the elements '4l 'tobe adjusted-to different points along the .periphery of disc 40. Upon depression of a but- -ton 42, a pin 45 is projected tothe rear of the ndisc ="40.\ The yprojected pin 45 has a path of :revolution such that it comes in contact With the endtoffa pivoted switch closure member 46, the

latter being limited in pivotable motion between a pair of stops 4l. The upper end of switch closure member 46 is provided with a widened edge,

.one point of which is capable of lmoving the con- :tact element331into circuit oli position when :theipin'45 is moved into abutting position against VAthefm'ember 4E.

`When the disc `lll is rotated lin one direction :the .pin`45 associated with a particular depressed 40 vwith its plurality of carrier members 4l.

't'button "42 willmove the closure member 46 in 'the 'direction of rotation 'of the disc.

When the latter is rotated in the opposite sense, then a -pin v45 will move the member 46 in the opposite .direction.

However, regardless ofthe sense of rotation of disc'40, the pin 45, when shifted into through any desired mechanical coupling arrangement. For example, a 2 to l reduction =gear ratio is shown employed to 'mechanically .couple the tuning device 2l tothe rotatable disc 14u., 'Ihis reduction gearing comprises a small vdrive gear '46 which is rotated in unison with vdisc 4D; the driven gear 41 meshing with gear 46,'and in turn having a rigid connection to the tuning velement 2l.

ingeneral, therefore, it Will be seen that the -manually adjustable tuning device of the receivfing system comprises Aa rotatable station selector vvdisc Vprovided with a plurality of independent station selecting buttons 42.

The tuning process .involves the insertion of the users finger in the borehousing a button 42, assuming the button has been depressed, and the rotation of the dial The rotation ceases when the particular pin 45 moves into contact with the pivotable closure member y4t, and the latter moves into contact with one .of-the stop pins 4l. This results in the rendering of inoperative at that point, as well .as Aa positive arresting of the rotation of dial 40. The button 42 is releasedthereby withdrawing pin 45, and opening switch 3l.

, The constructional details of the selector dial and its plurality of button carrier members will now .be considered. Particular attention is directed to Figs. 2 to 5 inclusive for these constructional details. In Fig. 2 there is shown the appearance of the station selector mechanism when viewed from the front of the operating .panel of a radio receiver. The disc 40 is provided, concentrically therewith, with an annular Adial bearing scale indicia l which denote the variousfrequencies to be received. Where the receiveris of the multi-range type, this circular dial 50 will bear-a plurality of scale ranges to correspond tothe different frequency bands of the receiver. The scale 5!) is rigidly secured to theouter face of disc 4l) in any desired manner; rotation of the disc k4l) therefore also resulting 'in rotation of the dial 50. f

=Each of the button carrier members 4I is bifurcated at the point of contact with the periph- -ery of disc 40. .As shown in Fig. 3 in greater switch 3l.

eisfproviuedffor Cooperation-,With-the ends ofxad- "detail, each ofthe members 4I is rigidlysecured to a predetermined position on the periphery of disc by means of the threaded coupling between screw 43 and the threaded bore provided in one of the legs 5l of the bifurcated portion of each of members 4l. Each of screws 43 is provided with a ball tip 52, the tip being shaped to complement the shape ofthe groove 44. 'I'hat is to say, the cross section of groove 44 will be substantially semi-circular so as to receive snugly the semi-circular contour of the ball tip 52. It will now be seen that a member 4I can be substantially rigidly secured to the periphery of disc 4H by the use of a screw driver, which is employed to rotate the desired screw 43. The buttons 42 are disposed within bores provided at the free ends of each carrier member 4 I.

As shown in Fig. 3 a button 42 comprises a shank Si! which is adapted to reciprocate through a narrow bore provided at the rear face of the member 4|. This rear bore widens into a second bore adapted to receive a spring 6| which normally maintains the head 62 of a button in a position such that the exposed face of the head 52 is substantially in the same plane with'theA lremainder of the Aexposed face of member 4I.

The head 32 of each button is arranged to reciprocate within a third and `wider bore 63. The head 62 may comprise, as shown in Fig. 3, a comparatively narrow recessed casing within which is disposed a circular station designation plate 64y having its upper face in contact with a transparent protective circular plate 65. As shown in Fig. 2, the head of each button will, therefore, have exposed to the View of the set user the various station call letters. Those shown in Fig. 2 represent' the various station call letters of broadcast stations encountered in the New York City area.

The shank B of each button device 42 is providedy with a normally protruding pin 1D. 'Ihe portion Aof the pin "lll between shank 50 and the rear tip of the pin is in threaded engagement with a nut il. The latter nut functions as a stop nut, and its face, in contact with the rear face of ear 4l, limits the movement of pin 'l0 in the direction of Vthe operating panel. Upon "movement of the button head B2 in a direction to compress spring 5I it will'be seen that the pin 'lll is moved into alignment with the path of movement of the double bell crank lever switch 415 which functions to close the AFC control Upon removing the depressing force from the button head 62, the spring 6| pushes the head 62 into `its normal position, and thus retracts the pin 'Hl from the path of the lever 4B.

The AFC switch 3l, asr shown in detail in Figs. 4 and 5, comprises the contact elements 32 and 33. The element 32, as well as element 33, has

one end thereof positively gripped between insulaton spacers l2. The contact element 33 has spaced therefrom a presser strip 13, one end of which is also gripped between insulation spacers. The bolts i4 function to rigidly secure together the various `insulation spacers, and maintain the ends of strips 32, 33 and 13 in spaced relation. The nxed ends of Contact elements s2 and 33 project beyond'the spacers T2, and numerals 'l5 and i6 designate these projecting ends which act as connecting terminals to the lead 34 and ground. The free end of element 32 is provided with a button Tl, and the free end ofcontact element 33 is provided with a contact pin 78.

v y member 46, isvrigidlysecured toa support plate` 82, the latter being' spaced from the operating upper edge, the bolt 8l.

Since the strip 32 is in metallic `engagement with the` button 511and'the'same is true of element 33 and its pin 18, contact between ele` ments 11 and 18 results in a closing of the cir- 46 showing its relation totheswitch elements when it is moved into contact ,with pin 41. The

.full line position of member 46 in Fig. 5 shows its relation to switch 3l, whenthe depending portion 46'` is movedinto contact with stop 41'.

The upper edge 30 of ,member 46 `is movedlout of contact `with the under surface of presser strip 13 whenever the depending portion 46 is swung towards either of the stopsi41 or'41. `It will also be seenthat regardless of the direction of movement of the depending portion 46', the contact elements 32and y,33 will be brought into electrical association by the front and rear cam edges of the upper lportion ofmember 46. Of course, the elements 32, 33and`13 are made of` flexible metallic strips` so that when the cam edges of edge Sillare moved lalong the under face of strip 13, the kthree spaced strips willbe capable of yielding in the direction in which they are urged. The bolt 8l, `which acts asthe pivot point for panel 83 of the receiver. As shown inFig. 3, the frontpanel 83 of the receiver is provided vwith a metallicring 84. The disc 48 is disposed concentrically with respect to the ring 84, and as seen in Fig. 2, `the ring 84 `servesas anouter setting for the disc and button carrier assembly. Itwill` be observed that there is a substantial peripheral space between the periphery of the circle of revolution of the button carriers, and the inner circular edgeof ring 84. The spaced plate 82 has secured to it, at a short distance from its 'Ihe stops 41 and 41' are 'secured to the front face of plate 82, the stops being spaced from each other in the manner shown in Fig. 4. The depending portion 46of member 46 has its rear face in contact with the front face of plate 82, so that when member 46 is shifted between the stops 41 and 41', its rear face is in sliding contact with the front face of The plate 82 'is rigidly secured to the chassis of the receiver inany desired manner, and through the center thereof there is provided an aperture which acts as abearing for the shaft 85, which is integral with the 'rotor condenser shaft 86.` The `gear 81 is secured `to the end of shaft 85 in any` conventional manner, and gear 81 meshes with driving gear 8,8." The gear 88 is pinned to the in tegral hub 88 of disc 46. The hub 88` is provided with a tubular extension 80, the latter extending to the rear of hub 89, and through a second aperture in plate 82. The extension and hub 89 is provided with af bore in which is disposed the,

horizontal portion Si of the fixed index arm 92. As clearlyshown in Fig. 3, the index arm 92 is formed from a single element, the vertical eX- posed index arm 92 :being maintained in the same fixed position by virtue of a downwardly directed Normally the upper edge i condenser element of the radio receiver.

'through 180.

. bent portion 93, which is secured to the rear face of'plate 82 in any conventional manner`-` The shaft 86 of the uni-controlled gangof condensers` is .additionally coupled,` if desired, to a conventional form of tuning knob94l As clearly shown 3, the tuning knob 94 may be pro-` vided inthe lowermost` portion of circular ring 84,

and in alignment with theindex arm 92. A shaft i 951s provided, which may be arranged parallel' tocondenser shaft 86,` and this shaft had an end thereof which has the knob 94 secured thereto. .The manually rotatable shaft 95 can be mechanically coupled to condenser shaft 86 in any conventional. fashion; a belt and pulley arrangement 86 being shown by vway of example. It is to be clearly understood,.however, that the tuning knob 94 and its associated mechanical coupling to condenser shaft 86, may be entirely omitted; since it is only'necessary to use the` station selector dial 40; f i

The numeral 91 designates the variable tuning .not believed necessaryto` describe the construction of this element since those skilled in the art are fully awareof such construction. It is only believed necessary to point out that the numeral 21` denotes the conventional gang of variable con` densers corresponding tothe variable tuning con# densers 28 and I ofFig. 1. It is also pointed out that gears 81 and'88 ofiFig. 3 correspond respectively to gears 41 fand 46 ofFig. l. l It will now` be .seen that as abutton 42 is depressed, and the dial assembly 48'is` rotated, the condenservshaft 86 will be rotated by virtuev of the gearing 88--81. Since the index on-92 'is rigidly anchored with respect to the rotating dial face 50, there is supplied, in addition to the station designations on the button faces, kilocycle designations to` de` note theposition. of condenser shaft 86 at any l K rection.` Dueto theconstruction of conventional variablel tuning `condensers, the` condenser` shaft 86 cannot becontinued in adjustment in the same vdirection after being `adjusted into complete meshing with the stators; neither can the rotor yshaft be continued in adjustment in the same -directionafter the rotors have been rotated completely out of mesh'with the stators.

However, between these two'limting positions, `the rotor" shaft 86 can be adjusted in clockwise or counterrclockwise sense. As iswell known,4 this adjust-` ment between the` limitingpositions is `only it is desired to initially calibratethe selector mechanism, orwhether` it is desired to re-calibrate 4the selector mechanism when areceiver is moved from one broadcast area into a relatively distant area,` it is only necessary to rotate the Acondenser shaft 86 by moving the dial 40 `until a station is heard ywithout appreciable distortion. At that setting of the ,condenser shaft 86a button carrier member r4I` isshifted along the periphery of dial 40'until pin 10 contacts portion 46' of Henceaz to 1 reduction ratio` gearing is used between shaft 8,6 and dial 40` tor secure advantage of 360 on the dial 48.

is n

member 46, and moves the latter against one of the stops 4l or 4l. At that position of member 4I, .its screw 43 is tightened to fix member 4I to the dial. 4D at the switch 3l closing position.

'I'his procedure may then be repeated for as many of the remaining carrier members 4I as is desired. Of course, the calibration may be accomplished by. employing the tuning knob 94, Where one is provided on the receiver. If the receiver is of the multi-range type, and the station selector dial l4I) .is used for the broadcast band exclusively, then it will be desirable to provide the tuning knob S4 for operation in the shorter wave bands. As stated before, the entire 360 of the selector dial 40 is utilized by Virtue ofthe reduction. gearing 88-81; this permits a wider distribution of members 4l on the selector dial.

The two members 3l and 46 definitely `assure reception of a desired station by causing the. AFC to be .rendered inoperative. This is accomplished during the portion of thev tuning operation just prior to the tuning condenser settingl at which the desired signal .would be obtained with the AFC in inoperative condition. When the variable. condenser rotation is such/that the condenser shaft 86 has adjusted the rotors of con.- denser 91 to tune the oscillator and signal circuits within the channel of the desired station, then the AFC is again rendered operative and completes the tuning operation accurately. Considered in mechanical procedure, this electrical sequence of tuning steps is accomplished in the following manner. v

Assuming that station WINS is being received, as shownin Fig. 2, and it is desired to tune the receiver to station WEAF; it is lonly necessary to insert a finger into the carrier member 4I provided with the WEAF button. AThis is accomplished by pressing down on the WEAF button. The entire selector dial assembly is then rotated in clockwise, or counter-clockwise, direction depending on the position of the condenser rotors. `There will be no obstruction to the movement of the WINS button because its pin 10. is in retracted position. The projected pin 'I6 of the WEAF button will cause rotation of dial 4i! to cease as soon as the pin strikes the depending portion 46 of member 46, and causes portion 46 to abut one of the stop pins 41 or 41. When the user of the set observes that further movement.

of the dial 40 is impossible, then it is merely necessary to remove the finger from the WEAF button. Removal of the pin 'l0 of the WEAF button permits the member 46 to attain its position shown in Fig. 4, thus opening the switch, 3D and restoring operation of the AFC. When the AFC becomes operative, it immediately functions to adjust the local oscillator frequency so as to accurately tune the receiver to WEAF. It will, therefore, be seen that the initial calibration of the selector dial need not be Very accurate. The action of the AFC is such that it will automatically and accurately tune the receiver after the receiver has been approximately tuned by adjustment manually of condenser shaft 86.

v, Of course, the station indicia on each button 42 may be made of Amaterial vwhich glows inthe dark, such materials being well known; thereby facilitating adjustment of the dial in the darkness, as in the case of an automobile radio receiver employed in night driving. Again, the station indicia may be in braille so .that blind persons may` easilyy use the mechanism.V

The switch so, also comming the Arc net..

Work, may be used when it is desired to render the AFC inoperative for a long period of time, and independently of the switch. 3l. Again, it is to be noted that while the resiliency of strips 1.3, 33 and 32 can be relied on to restore the member 46 to its normal position shown in Fig. 4, it is obvious that the portion 46 may be designed to nor mally. maintain the member 46 in its median position. While the dial 40 canbe positioned on the operating panel above the tuning knob, tone control knobandvolume control knob, it is within'the scope of my invention to dispose the selector dialat the side of the cabinet for aesthetic reasons. Again, if it is desired' to keep the selector dial on the front panel, and if for design purposes it is desired to keep the dial normally hidden from view, a slidable, or pivotable, door may be used to. cover the selector dial. From Fig. 2 it will. be seen that there is plenty of space between members 4.I on dial 40 to provide for re calibration when the receiver ismoved from one broadcasting area to an area where entirely different stations are broadcasting.

It is believed that the electrical operation of the AFC, as the receiver is tuned, will be obvious from the aforegoing description. As soon as the receiver is tuned Within a desired signal channel, the AFC will immediately function to adjust the oscillatorfrequency so as to produce I. F. energy substantially equal to the operating I. F. Because of. thisfunctioning of the AFC network, an additional .advantage is secured by virtue of the selector dial construction. Since the receiver is equipped with an AVC network it functions to reduce the sensitivity of the signal selector circuits as long as'signal energy is `applied to the AVC rectifier.

Since the .AFC network is operative at all times in a receiving system embodying the present invention,. it necessarilyfollows that signal energy will be impressed on. the AVC rectifier at all times. In other words, vthe AVC connection Il in Fig. 1 is .practically functioning at all times to reduce the sensitivity of the signal stages preceding. the I. F. network. This is particularly true when tuning from one station position of the selector dial 4!) to another position. Whereas in a conventional radio receiver equipped with AVC, inter-station adjustment ci. the receiver results in much noise; the present receiving system and its station selector mechanism produces quiet tuning between channels.. Further, it will be seen that this is accomplished without the use of any auxiliary, and well known types of, noise suppressor networks. In-other words, the AFC network not only :functions to render the tuning operation simple and accurate; but it also cooperates with the AVC network to provide quiet interchannel operation.

A modiiication of the selector mechanism is illustrated in Fig. 6. This latter figure shows the appearance of the selector mechanism as viewed from the operating panel. It will be seen that it comprises a disc Ill provided on its outer face with a plurality ci spaced tubular devices I FHI The outer face of disc HBO is also provided with a concentric scale disc 102, a stationary scale arm IIlS depending from the rear of the operating panel IM, and cooperating with the indicia IUS provided on the disc 162. In Fie'. 7 there is shown in detail the manner of constructing one of the tubular finger positioning devices IUI. It willbeobserved that each of the devices IUI comprises a cylindrical casing HIB having a base i which grips the peripheral edge of disc |60. Each of casings I |56 is provided with a rounded periphery at the exposed opening Ii, and a false bot-` torn discI I Iis provided at an intermediate point along the length of casing 06. The disc III pears on its outer face station indicia,and the latter areclearly shown in Fig. 6. The `disc |00 is directly coupled to the condensershaft H2. The numeral H3 designates, in Fig. 8, the gang of-v condensers, and itv will be observed that the rotor shaft H2 is directly coupled to the disc |00 by any well known form of mechanical coupling H4. In view of this construction the finger` positioning devices II can only be arranged along 180 of the exposed face of disc |00; this follows 't from the fact that the rotors of the variable conbottom of a 'support plate H1, the latter beingA spaced from, and positioned rearwardly of,` the disc Hill." The circuit closing end of contactor H4 is resiliently secured to a bracket Hi8 which depends from the lug H5.` This is. accomplished by securing spring H9 between the'free end of bracketIlS and the contacting end of the con- 40y tactor H4.

The' spring-retained end oi. contactor H4 is provided with opposed'contact points |20 and j |2I; and thesepoints are arranged to cooperate with contacts and |2I respectively. .lattertwo contacts are connected in common, and are provided with a single connection to the AFC network. The ground connection is provdedl'to thefcontactor H4, and a pair of stops |22 and |23 'are provided on either `side of the contactor H4 in order tolinnt the arcuate motion thereof. 'Ihe upper end ofthe contacter I4 is providedwith a configuration as shown in Fig. `6, and it will be observed that this conguration generally comprises a pair of opposed t concave arcs. The lpurpose of this conguration is to adapt the upper opposed edges of the free endof contactor IUI-to the-contourof a'inger ypositioned ina device IOI.

Itlwill now be seen that a finger, disposed in fafgiven'icylind'er IIlI, shifts the contactor H4 into AFC circuit closing position when the finger contacts the upper edge of the contactor and rotation of vdisc I mi is continued.' As shown inY Fig.V 6, and assuming that WABC isdesired for reception, it will be seen that the finger of the user will shift the contactor H4 into the dotted line position H4'. In this position, the stop |23 limits further motion of the contactor, and causes electrical contact between point` |2Il and contact I2I.` In this position, the AFC network is in` operative,and normal tuning is permitted. As

i soonas the iinger of the user is removed from theWABC cylinder, the spring H9 retracts the contactor I I4 into normal position, and the AFC network is operative to accurately tunethe receiver.` n

In designingvthe stop device for the selector dial, whether itbe for the form shown in Fig. 3, or the formshown in Fig. 6, it is necessary to have the pivotable switch closure member shifting in accordance with the direction of `rotation of the selector dial.` `This assures `the tuning means coming to rest in the same location regardless of whether the direction of rotation is` clockwise or counter-clockwise. Mechanically, this action is secured by permitting the toggle member to be displaced from its normal, `orcenter, position a distance equal to the radius ofthe toggle actuating means; in Fig. 3this actuating means is a pin projected by a depressed button.` Here, the abovementioned radiusuis the radius of the button pin. In `the iinger-'actuatedmodication, this radius is that of the finger-positioning aperture. l

The selector mechanism is shown in still' further simplified form in Figs. 9 and 10. In, this arrangement, the selector mechanism comprises a disc having a bore |3I, the bore receiving `therotor shaft |32 of the'gang of"condensers.

In other words, the disc |3Ufis directly coupled` to the rotorshaft. vA semi-circular slot |33 is pro vided in the body of disc |30, thus providing a rear segment |34 and a front segment |35. j Thefront, or selector, segment |35 is provided witha plurality of spaced openings |36, and `the;inner -iace of the rear segment |34 isuprovided with a station designation disc |31. The' station indicia.

|31' are provided adjacent the peripheral edge.

of plate I3i; the indicia being providedat points such that they canbe viewed thro-ugh theirA cor-1` `responding selector openings |36. fAs shown in Fig. 9, each opening |36 will thensurround ar corresponding station designation |31".`

Of course, the diameter of` each opening |36` should besuch that thefmger size of the average understood that the AFC switch construction inl l lconnection with Figs. 6, 'I and 8 is tobeemployed iny connectionY with this `selector modication. The association of the form shown in Fig. 9 with an AFC switch is not shownY because it is beappreciatethe manner of" this mechanical asso ciaton from Figs. 6,7 and4 8. u

`It will be iobservedthat in the last two modifications described, the station selectordevices are` limited to an 180 distribution .along the periph-V ery of the station selector disc. The entire, circumference of the selector rdisc may. be used by providing an additional AFC switch diametrically opposite to that shown `in Figf. I This form Aof selector mechanismis shown `in Figs. 11 and 12. The selector disc andnger posi` tioning devices are similar in construction to the form shown in Figs. 9 and 10. 4Thatis to say, the numeral|40 designates a selector disc-,provided with spaced iinger vpositioning openings. I4|

tion` |42 is provided withthe station indicia disc through the different openings |4| One AFC switch is located lowermost point of disc |40, and a second' AFC switch I5I is positioned` diametrically opposite `lieved that those skilled in the artwillreadi1y sos. f

con

adjacent thev y 7oz'- switch |50. It is to be clearly understood that l both these `switches are constructedas shownjin Figs. 6. and 8.* For this reason, these switches are schematically.r represented yin Figsuil and l2.`

' 35ian. angular: distance greater than 180.

The common connection to groundv from the contactors of switches 150 and ISI is shown in' Fig. 11and.. the latter additionally shows the common connections from the pairs of contacts of each of switches l5@ and ii to .the AFC network. f

In this way, it is possible to use either of the modiiications shown in Figs. 8 and 9, and yet have a Wider distribution of linger positioning de- 10 vices along the periphery of the selector disc. This canbe easily seen from the iact that since the rotors of the variable condenser, to which shaft l32in Fig. l2 is connected, have a maximum rotation of ,180", it is only necessary to position 151 half `the stations on half the disc Mld, and the other half of the stations along the periphery of the other half oi the disc. Because of this arrangement, and the provision of a pair of switches I5!)v and 85|, regardless of the position of the ro- W3 tors of the variable condenser, the maximum rotation of disc Mii will not exceed 1809.

It is thereby possible to have the spacing between lnger position openings Uil much wider than in the modifications of Figs-6 and 9'; fur- 25:3 ther, the advantage over the modiiication shown inllfigl.l 1 resides in the fact that no mechanical gearing isemployed between the selector mechanism and the rotor shaft |32 and yet the full 360 of. the sel-ector'disc is taken advantage of. An 301; additional advantage of the modification shown in Figs. 11 and l2 overthat shownin Fig. l resides in the fact that to adjust thejrotor shaft i325 .to anydesired station setting from any last.

' settngthe disc M0 need not be adjusted through In order to distinguish the stations on half of the disc ma fromthestanonson the other half, a differential, coloring can be employed on the station indicia.

While I have indicated and described several constructions for carrying my invention into efiect, it will be apparentto oneskilled in the art that myinvention is by'no means limited to the particular constructions shown yand described, 45t but that many modifications may be made without` departing from the scope of my invention, as set-forth in the'appended claims,

What I vclaim is:

'-ll In-combination with the adjustable tuning 505'? device of a radio receiver, supplemental means for tuning the receiver, a device for controlling the operation of the supplemental means, a rotatable station-selector discv arranged to vary said tuning device to different station reception-posilietionsa plurality of independent finger positioning devices mechanically associated with said disc, and means, relatively xed with respect to said rotatable disc, for stopping the rotation of said disc, and actuating said control device upon 6055' adjustment of a selectedone of said devices to a iixed reference point.

2. In combination with the adjustable tuning device of a radio receiver, a supplemental tuning device, a rotatable station selector disc arranged "gto vary said tuning device to different station reception positions, a plurality of independent finger positioning devices mechanically associated with said disc, and means, relatively fixed 1 70,with respect to said rotatable disc for stopping the rotationnof' said disc upon adjustment of a selected *one of said devices to a xed reference point, said stopping means comprising an element. arranged to rock between a pair of stop u; members andmeansrcooperating with the element at its rocking limits to control said supplemental device.

3. In combination with the adjustable tuning device of a radio receiver, a supplemental tuning device, a rotatable station selector disc arranged IiI to vary said tuning device to different station reception positions, a plurality of independent fin-ger positioning devices mechanically associated with said disc, and means, relatively iixed with respect to said rotatable disc for stopping 10 the rotation of said disc upon adjustment of a selected one of said devices to a fixed reference point, said stopping means including a member arranged to rock between a pair of limiting points, means cooperating with said member at 15.- its rocking limits to control said supplemental device, and means mechanically associated with each of said independent devices for 'rocking said member.

4. In combination with the adjustable tuning f device of a radio receiver, a supplemental tuning device, a rotatable station selector disc arranged to rvary said tuning device to diierent station reception positions, a plurality of independent finger positioning devices mechanically `asso- I ciated with said disc, and means, relatively fixedV `with respect to said rotatable disc for stopping the rotation of said disc upon adjustment of a selected one of said devices to a iixed reference point, said stopping means being constructed and 3 0 arranged to shift between a pair of limiting posi- `tio-ns in accordance with the direction of rotation of said disc andv means cooperating withv said stopping means at its shifting limits to control said supplemental device.

5. In combination with the adjustable tuning device of a radio receiver, a line tuning mechanism, a rotatable station selector disc arranged to vary said tuning device to different station reception positions, means controlling the effect 40. of said mechanism, a plurality of -independent finger positioning devices mechanically associated with said disc, and means, relatively iixed with respect to said rotatable disc for stopping the rotation of said disc upon adjustment of a selected one of said devices to a fixed reference point, each of said positioning devices comprising a depressible button carrier member, and each depressible button being provided with a pin adapted to contact said stoppingmeansv to actu- 50, ate said controlling means.

6. In combination with the adjustable tuning device of a radio receiver, a rotatable station selector disc arranged'to vary said tuning device to different station reception positions, a plurality of independent ringer positioning devices mechanically associated with said disc, each of said devices comprising a member provided with a bore, a spring-biased button means in each bore, and means, relatively fixed with respect` to said 60,' rotatable disc for stopping the rotation of said disc upon adjustment of a selected one of said devices to a fixed reference point, each of said independent devices including means for adjusting a device to any desired position on the disc u for calibration thereof, a pin carried by each of said button means, and each button means being responsive to pressure of a linger for projecting a pin from a positioning device in such a manner that a pin comes in contact with the stopping 70.1 means.

'7. In combination with the adjustable tuning device of a'radio receiver, a signal-responsive control circuit, a rotatable station selector disc arranged to vary said-tuningdevice to different :4

and means, relatively fixed with respect to said station yreception positions, a plurality of independent linger positioning devicesl mechanically associated With said disc, and means, relatively fixed with respect to said rotatabledisc for stopping the rotation of said disc upon adjustment of a selectedone of said devices to a xed reference point, each of said positioning devices being provided with a bore to receive the nger of the user, and said stopping means including a shiftable element adapted to be` adjusted between a pair of limiting positions, said shiftable element being included in a switch device for controlling the operation of said control circuit, andthe path of rotation of said disc being suchthat the said usersnger comes into contact with said shiftable element. l

8. In combination with the adjustable tuning device of a'radio receiver, a ne tuning device, means for controlling the operation of the latter, a rotatable station selector disc arranged to vary said tuning device to different station reception positions, said disc being provided` with a plurality of independent finger positioning devices,

rotatable disc, for stopping the rotation of said disc and actuating said controlling means upon adjustment-of a selected one of said devices to a fixed reference point corresponding to the position of said stopping means. l y 9. In combination with the adjustable tuning device of a radio receiver, a supplemental tuning device, a rotatable station selector disc arranged to vary said tuning device toy different station reception positions, said disc being provided with a plurality of independent finger positioning devices, 4and means, relatively fixed with respect said disc vupon adjustment of a selected one of said devices to a fixed reference point corresponding to the position of said stopping means, each of said finger positioning devices comprising an aperture provided in the disc and `saidstopping means comprising an adjustable element constructed andarranged to be rocked between a pair of limiting positions and means cooperating with the` element at its rocking limits to control said supplemental device.

10. In combination with the adjustable tuning device of avradio receiver, a circuit for controlling signal reception, a rotatable station selector disc arranged to vary said tuning device to dierent station reception positions, said disc being provided with `a plurality of independent finger positioning4 devices, and means, relatively fixed with respect to vsaid rotatable disc Vfor stopping the rotation of said disc upon adjustment of a selected "one of said devices to a fixed I reference point corresponding to the position of said stopping means, said stopping means being included as a control switch insaid controlling circuit, and an additional stopping means arranged adjacent said disc` at a point diametrically opposite the yposition of the first stopping'` Vsuperheterodyne type, automatic frequency control means, responsive to received signal energy,

for .adjusting the local oscillator frequency to a` magnitude such that the vfrequency of the in- "termediate frequency energy is made to approach an voperating frequency value, a mechanism for rendering the irequricy control inoperative, A'an adjustable station selector constructed and varranged to vary the` position of the adjustable tuning device of the receiver, said selector beine" respect to said selector that the-mechanism is actuated when a positioning-' device isadjuste toapredetermined reference point. f l2. In combination with a radio receiver of th superheterodyne type, automatic frequency control means, responsive to received `signal energy,

for adjusting the local oscillator frequency to `a magnitude such that the frequency` of the intermediate frequency energy is made to approach y an operating frequency value, switch means for 'ngerpositioning devices for adjusting `the selector to different desired station settings, and

said switch means being positioned in the path of movement of said devicesin such aimarinerI that the switch is actuated when a device is adjusted to apredetermined' reference pointgand additional means for 1renderingsaid switch inactivev to affect the frequency control upon removal ofthe finger from the` selected device. -i i 13. In combination `with'a radio receiver of the superheterodyne type, automatic frequency control means, responsiveA to received signal Veriy c ergy, for adjusting the local oscillator` frequency to said rotatable disc for stopping the rotation ofv to a magnitude such thatthe frequency of the intermediate frequency energy is made to appreach an` operating Vfrequency va1ueswitch means for rendering thelfrcquency` control `inoperative, an adjustable station selector constructed and arranged to` vary the position of theadjustable device of the receiver,

said selector being provided with a plurality of independent` finger positioningdevices for adjusting. the selector toi different desired station settings, and said switchmeans being mechani-` cally associatedwith said devices in such a mari-fv the superheterodyne type, vautomatic frequency control means, responsive to received signalenergy, for adjusting the` local oscillator frequency to a magnitude such` that `the frequency ofthe intermediate frequency `energy is madeitoapproachfan operating frequency value, switch means for renderingvthe frequency control'inoperative, an'adjustable station selector constructedand arranged tovary the position of.

the adjustable tuning device ofthe receiver, said selector beingprovided with a plurality of independent fingerpcsitioning devices for adjusting the selectorto different desired station settings,`

and said switch means being mechanicallycy as-Y sociated with said devices in such a manner that the switch is actuated when a device is adjusted toa predetermined reference point, an adjust-1 able elementadapted *to bevaried in` position switchmeans at each of said limiting pointajsaid adjustable. element being mechanically associated with said independent devices in such a manner that the adjustable element is actuated forrectifying the intermediatefrequency energy and a local oscillator adapted to impress locally produced oscillations upon said rst detector, an adjustable -tuning device electrically associated with said first detector and oscillator,y means, responsive to.r a variation of frequency of said intermediate frequency energy from the operating frequency, for adjusting the oscillator frequency in a sense to cause said intermediate frequency energy to approach said operating frequency, a switch device for controlling the operation of said oscillator frequency control means, means for varying said adjustable tuning device to i predetermined positions, and additional means for actuating said switch device to render the frequency control means inoperative solelyv atsaidpredetermined adjusted positions-of the weine device- A176. In` a superheterodyne receiver provided With-at least a first detector adapted to produce intermediateA frequency energy of a predetermined operating intermediate frequency, means for rectifying the intermediate frequency energy and-alocaloscillator adapted to impress locally produced oscillations upon said first detector, an adjustable ytuning device electrically associated withsaid first detector and oscillator, means, responsive toa variation of frequency of said intermediate frequency energyfrom the. operating frequency, for adjusting the oscillator frequency inta sense-to cause said intermediate frequency energyto approachsaid operating frequency,.a switchdevice for controlling the operation vof saidoscillator frequency control means, means for varyingsaid adjustable tuning device topredeterminedpositions, and additional means for actuating said switch device to render the frequency -control means inoperative solely at said predetermined adjusted positions of the tuning, device, signal amplification reduction means, responsive to rectified intermediate frequency energy, forautomatically maintaining the signal amplitude substantially uniformat the said rectifier when thev received signalamplitude increases, and said frequency control means acting to cause said intermediate frequency energy tdbe supplied to said signal-rectifier between said tuning. device-.positions'whereby the tuning operation between said positions is quiet.

. 17. In a radio receiver of the type comprisingy amain tuning device and a supplemental signalactuated tuningmechanism for securing accurate tuning at selected station positions of the main device, means for controlling the operation of the .supplemental mechanism, an adjustable station selector constructed and arranged 'to adjust said main device to'selected positions, said selector. being provided with a plurality of independentstation representation devices for positioning ,an index element, and means constructed and arranged simultaneously to stop the adjustmentxof said selector upon adjustment 'of the positioned ,index element to a fixed reference pointcorrespondingpto the .position of said stop.-

Lping means, and to-.actuate said control'means...

t 118:11; a-t'radio, receiver-of the type provided withfaflstation selecting circuit including a main tuningelement, an automatic tuning control arrangement for insuring accurate tuning of the receiver at selected positions of the.` main element, means for rendering said automatic control ineffective, and additional means, responsive to adjustment of said main tuning element, for actu-l ating saidlast means at said selected positions.

1,9.,Selective adjusting mechanism for tuning radioh-receiversA embodying an automatic frequency control circuit comprising a manually shiftable element drivingly connected with a tunable element of said receiver and selectively operable means for` stopping the means of the Vshiftable element when the same and'said tunable element reach a desired tuned position, and means operatively associated with said stop means for grounding said automatic frequencycontrol circuit momentarily as said desired tuned posi-tion is reached.

20. Selective adjusting mechanism comprising rotatable means including a portion formed with a series of openings adapted to receive the finger of anoperator-when turning the rotatable means,y stopgrneans for each opening including a button portionA extending in an opening and depressible therein bythe. linger of the' operator, said stopmeans being normally'inactive but being adapted upon depressionr of the corresponding button in its, openingv to stop rotation of the rotatable means-whenthesame reaches an adjusted position determinedfby said stop.

21. Selective.k adjusting mechanism comprising amanually 'shiftable element and selective means operable during and as a part ofthe shifting of saidi'elementr to stop the same when. a desired adjusted position is reached, said selective means comprising-av plurality .of `selectors individually andE selectively depressible on said manually shiftableelement, each depressible selector comprising Vabutton. member 'andl a stem-like stop elementi aXially.-y movable onthe manually shiftablel element, resilient means arranged in contact with said-'button Vmember and applying pressure L.-

directly :thereto thereby normally urging-3 said stop element toward inactive position on the shiftable element, and means forming a cooperatingy stop. adaptedl to engage said stopfelement when the selector is depressed on said shiftable element whereby to stop the shiftable-element in a position determined by said stop element.

22.'.Selective adjusting mechanism comprising rotatable means including a portion formed'with openings whereby said means may be grasped in turning the same, means extending in said openings and forming stops selectively operable in eifectingturning movement to check'said movement when said rotatable means reaches a desired adjusted position determined by the selected stop;

v23. In combination with the adjustable tuning condenser ofa radio receiver, a rotatable station selector member arranged to actuate said condenser; to different station reception positions, ai. plurality of selectively operable pushbuttons` mechanically associated with said selec.- tormember,z means relatively-fixed with respect to said rotatable selector member for stopping the: rotation of said member upon adjustmentof afselectedione of said push-buttons to a xed reference point, a control circuit included in said receiverand `havinga normally open switch, and Ameanscontrolled by .said push-buttons at their limits of .travel for actuating the switch to lclosed position.; l

l 24. In combination, an adjustable tuning condenser of a radio receiver, a rotatable station selector member arranged' to adjust said condenser to different station reception positions, a plurality of selectively operable push-buttons carried by said selector member and capable of sliding movement in a direction normal to the direction of rotation of the selector member, a stop pin carried by each push-button, means co- 10 operating with the stoppin of an operated pushber at a desired tuning position upon actuation of a push-button and the simultaneous rotation of the selector member, a control circuit included in said receiver and having a normally open switch, and means controlled by said stop pin at its limit of travel to actuate the switch to closed position.

DUDLEY E. FOSTER.

button to arrest the motion of the selector mem-

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