US2154778A - Radio tuner - Google Patents

Description

April 13, 1939- w. J. SCHNELL 2,154,778

RADIO TUNER mp Ma 1N VENTOR.

Jb/mlfi W 11 m w ATTORNEYS;

Patented Apr. 18, 1939 PATENT OFFICE RADIO TUNER William J. Schnell, Berwyn, Ill., auignor to area tricai Research Laboratories Inc., Chicago, 111.,

a corporation of Illinois Application 111110 16, 1938, Serial No. 214,007

9 Claims.

This invention relates to an automatic" radio tuner. and particularly to a radio tuner of the push button type. a

It is an object of applicant's invention to provide a simple, compact and relatively inexpensive tuning device, preferably of the push button type, which is readily and precisely adjustable for the selection of desired broadcasting stations. It is another object of applicant's invention to provide in a radio tuner a plurality of selectively energizable electrical tuning elements or impedances, and to provide means for controlling the selective energization of said tuning elements or impedances which last mentioned means shall be individually adjustable exteriorly of the radio receiver selectively to vary the impedance of said tuning elements so that the selected tuning element will, whenever energized, tune the receiver to the desired station. 20 A more specific object of applicant's invention is to provide a tuning device comprising a plu-- rality of inductances or condensers wherein means is provided for selectively energizing said inductances or condensers to tune the radio re- 25 ceiver to a selected broadcast station, and wherein the selected control means is adjustable exteriorly of the receiver or from the front panel of the receiver by manual manipulation and without the use of any tool or device to individually 30 adjust or pre-set the impedance values of said inductances or condensers.

Other and further objects and advantages of the invention will be apparent from the following description when taken in connection with 35 the accompanying drawings, wherein:

Fig. 1 is a view in elevation of a radio receiver embodying the invention.

Fig. 2 is a fragmentary horizontal section.

taken substantially along the line 2-2 of Fig. 1. 40 Fig. 3 is a view of a portion of Fig. 2, but with the elements in a different position of operation. Fig. 4 is a fragmentary sectional view taken substantially along the line 4-4 of Fig. 2.

Fig. 5 is an enlarged fragmentary horizontal 45 section on the line H of Fig. 4. Fig. 6 is an enlarged fragmentary section alon the line 68 of Fig. 4.

Fig. '7 is a fragmentary section similar to Fig. 6, but showing a modification. 50 Fig. 8 is a fragmentary horizontal section taken substantially along the line 8-4 of Fig. I. Fig. 9 is a fragmentary section similar to Figs. 4 and 7, but showing a second modification.

Fig. 10 is a vertical section along the line ll- 55 ll of Fig. 9.

Fig. 11 is a schematic diagram of the electric circuit for the forms of Figs. 1 to 6 and Figs. '1 and Fig. 12 is a schematic diagram of the circuit for the forms of Figs. 9 and 10. 5

As shown in Fig. 1, the radio receiver 2 comprises the usual cabinet 4 having a tuning dial 6 over which moves a pointer 8 controlled by the usual manually operable knob iii which also, in the usual manner, controls the tuning adjust- 1 ment of the conventional gang tuning condenser. The receiver also comprises the usual tone and volume adjusters l2 and I4 respectively and in addition an automatic tuner ii for automatically adjusting or tuning the receiver to any desired 15 one of a plurality of selected broadcast stations. The automatic tuner i6 preferably comprises a plurality of push buttons l8 located exteriorly of the front panel of the radio receiver and carried by slidably and depressibly mounted bars or rods 22 extending through said front panel into the interior of the receiver.

Each rod 22 interiorly of the receiver is provided with a bifurcated portion or member 24 formed integrally with or rigidly fastened to the 25 rod. The bifurcated member or portion 24 is provided with a central opening preferably circular in cross section, to receive a sleeve or collar 26 carried by or secured to the end of a threaded rod 28. The bifurcated member or portion'24 is 30 slidable upon the sleeve or collar 26 which, therefore, acts as a guide for said member, and the sleeve is provided with a pin 30 received between the furcations of the bifurcated member or portion 24 so that the sleeve 26 and rod 28 may be rotated by rotation of the push button i8 and the rod 22. A tube 32, which may be of insulatory material, carries circumferentialiy thereof spaced induction coils or inductances 34 and 36. The tube 32 is secured to a supporting wall or flange 38 of a bracket 40 welded or otherwise fastened to the front wall 42 of the usual receiver chassis 44. This securing of the tube 32 to the wall or fiange 38 is accomplished by a sleeve 46 exteriorly threaded to receive a nut 48 clamping the sleeve against the wall or flange 38 and having an enlarged head 50 abutting the inwardly extending annular end flange 52 of the tube 32.

The inductivity or inductive value of the coils or inductances 34 and 36 is varied or adjustably 50 controlled by integrally connected magnetic cores 54 and 56 rigidly secured to the rod 28 within the tube 32. The sleeve 46 also provides a stationary nut compelling the rod 28 to move axially when rotated so as to vary the relative alinement 66 34 and 38, and for this purpose the sleeve 48 is internally threaded to receive the external threads of the rod 28. As shown in Fig. 11, there are a plurality of coils or inductances 34 and 38, each pair having the inductive values of its constituent coils controlled by a separate push button I8. One end of each coil 34 (Fig. 11) is connected in common by a wire 58, in which is interposed a condenser of the order of .01 of a microfarad, to the antenna lead 82 which lead is grounded through a resistor 84 of the order of 25,000 ohms. One side of a grounded condenser 88 of the order of .002 of a microfarad is connected to the common wire 58. One unit 88 of the manually adjustable gang condenser I0 is connected to the contact 12 of a switch I4 controlling the energization of a fixed inductance or coil I8. One end of the coil I8 is connected to the contact 18 of the switch I4 and the other end of said coil is connected to the common wire 58. A third contact 80 of the switch I4 is connected by a lead 82 to a common wire 84 connected to the signal control grid 88 of a combined amplifier and oscillator vacuum tube 88. The switch 14 is controlled in a manner later to be described by one of the push buttons I8 and when the coil 18 is energized, the condenser unit 88 is simultaneously connected therewith and to the control grid 88 so that the receiver may be manually tuned by manipulation of the control knob I0.

The other end of each of the coils 34 is connected to a contact of a switch 82, there being one switch 82 for each of the coils 34 and each of said switches being controlled by one of the push buttons I8. The contacts 84 of the switches 82 are connected in common by a wire 88 to one side of a fixed condenser 88 which is grounded at its other side. The other contacts I00 of the switches 82 are connected in common by the common wire 84 to the control grid 88 of the amplifying, oscillating tube 88.

One end of each of the coils 38 is connected by a common wire I02 to the anode electrode I04 of the oscillating section of the tube 88 through a condenser I05 of the order of .002 microfarad. The other end of each coil 38 is connected with the contact I08 of a switch I08 controlled simultaneously with the switch 82. The contact I I0 of each switch I08 is connected by a common wire II2 to one side of a fixed condenser II4 which is grounded at its other side. The contact II8 of each switch I08 is connected by a common wire II8 to the control grid I20 of the oscillator section of the tube 88. A second unit I22 of the manually adjusted gang condenser I0 is connected to the contact I24 of a switch I28 controlled simultaneously with the switch 14 by its associated push button III. A fixed inductance or coil I28 is connected at one end to the common wire I02 and at its other end to the contact I30 of the switch I28. The third contact I32 of the switch I28 is connected to the common wire I I8. A separately adjustable compensating condenser I34 is grounded at one side and its other side is connected to the common wire I02.

The output of the tube 88 may be fed in any conventional fashion to the succeeding tubes of the receiver. The usual automatic volume control (A. V. C.) may be connected to the common wire 58 and the source of plate potential for the oscillating section of the tube may be connected to the common wire I02 between the anode I04 and the condenser I05.

of the cores 54 and 58 with their respective coils All of the switches 82, together with switches I4 and I28, are mounted as a unit upon a support I38 (Fig. 2). The support I38 comprises front and rear plates I38 and I40 respectively and side plates I 42 and I44 respectively forming a frame or housing for the switches. The rear frame plate I40 is provided with inwardly turned upper and lower flanges I48 (Fig. 4) and the side frame plates I42 and I44 are provided with laterally bent flanges I48 (Fig. 2), the flanges I48 and I48 forming supporting and attaching surfaces for receiving upper and lower insulating plates or srips I50 and I52 respectively. The contacts 80 and 84 are arranged in pairs on the outer surface of the upper insulating plate. I50 and the contacts I00 for adjacent ones of the coils 34 are formed as a single blade secured to the upper surface of the plate I50 between adjacent pairs of the contacts 80 and 84. The contacts I08 and H0 are arranged in pairs and secured to the lower surface of the lower insulating plate I82 in the same manner as the contacts 80 and 84 are secured to the upper plate. The contacts I I8 are secured to the lower surface of the insulating plate I52 and are disposed in a manner similar to the disposition of the contacts I00 on the plate I50. Amovable switch blade I54 is adapted to connect each pair of contacts 80 and 84 to the adjacent contact blade I00. The contact blade I 54 comprises a headed portion adapted to bridge the space between the contacts 80 and 84 and an elongated portion in constant engagement with the switch blade I00 and adapted to bridge the space between this blade I00 and the contact blade 80 when the blade I 54 is moved to its upper position in Figs. 2 and 3 or to its righthand position in Fig. 4. The switch blade I54 comprises in addition a depending leg or flange I58 (Fig. 6) extending through a guide slot I58 in the insulating plate I50 and through an opening provided in an insulating plate or strip I80 which is mounted for slidable movement relative to the plate I50. The lower end of the depending leg or flange I58 is bent over into clamping engagement with the lower surface of the slide plate I80 so as to securely fasten the movable switch blade I54 to said slide plate. A similar switch blade I82 likewise mounted for slidable movement on the plate I52 is similarly secured or fastened to an insulating and slidable plate I84 identical to the slide plate I80. The plates or strips I80 and I84 are carried by a slide bar I 88 to which they are attached by lugs I88 passing through the strips I80 and I 84 and by clips I10 bent over the and edges of said strips into clamping engagement therewith. Notches I12 are formed in the opposite edges of the slide bar I88 (Fig. 4) to receive the inturned ends of the depending flanges of the switch blades I54 and I82, there being suflicient clearance between the walls of these notches and said inturned ends to prevent engagement between the slide bars and the movable switch blades. The slide bar I88 is formed with a reduced end portion I'I4 received in a guide opening in the rear frame plate I40, and a coiled spring I18 is interposed between said rear frame plate and the enlarged body portion of the slide bar I 88. The opposite reduced end portion I18 of the slide bar I88 extends forwardly through guide openings in the front frame plate I44 and the supporting plate 38, and at its forward edge is secured an L- shaped operating bar I80 having a bifurcated end portion I82, the furcations of which are received in an annular groove I 84 formed in the rod 22 I 34 and 22.

arse-no oriraithe forwardendofthcbifurcated mamber 'Ihefront faceofeachpushbutton I2,exoept one,isasat I22(1'lg.4) toreceiveatab ordisk al'ry nllsuitableindicia,suchasthecali lettersofthebroadcaststationforwhiahthe particular push button may be, as setforth,adjustedtotlmethereceiver..

The switch blades or contacts l2, I2, I24 and I22aresecuredtotheinsulating plates I22and I22inamannersimilartothecontacts22,24, I22 and Ill, and the contacts 22 and I22 are securedtosaidplatesfnamannersimilartothe contacts I22. The switch bladu I4 and I22 are formed similarly to the switch blades I24 and I22 and are similarly mounted for slidable movement upon the plates I52 and I22.

The remaining push button I2 is connected, in thesamemannerastheotherbuttonsareconnected. to the switches 22 and I22 and to the switches I4 and I22. This push button is also 9 vided with a recess to receive a markingtab indicative of its function, viz., to the tuning device.

A common latch lever or bar I22 extends through enlarged slots I22 in all of the slide bars I22 and through alined slots in the side frame plates I42 and I44. A coiled spring I22 interposed between the side plate I42 and a washer I24 bolted to the left end of the latch bar I22 normally urges said latch bar to the left as seen in Fig. 2. The latch bar I22 is provided with a plurality of latch fingers I22, one for each of the slide bars I 22 and each adapted to eng e a slot I22 in the associated slide bar to retain said slide bar in its rearwardly depressed position. Each latch finger I22 is formed with a cam surface 222 having camming engagement with the forward edge of the slot or opening I22.

The adjustment and operation of this form of the invention is as follows: The adjustable core elements 54 and 56 provide means for adjustably varying the permeability of the cores of the coils In order to adjust a push button for the selection of a desired station, said push button is first depressed to connect the selected coils 24 and 22 to the control grids 22 and I22 and to the fixed condensers 22 and H4. The depressed push button I2 is then rotated to rotate the rod 22 and through the bifurcated member or portion 24 causes rotation and axial movement of the rod 22. The axial movement of the rod 22 varies or adjusts the core elements 54 and 52 axially of the coils 24 and 22 and by varying the permeability of the cores, varies the impedance of said coils whereby the tuning circuits, of which the selected coils 24 and 22 form constituent parts, are adjustably pre-set in frequency so'that this push button and its operated elements will when operated effect the tuning of the receiver to the desired broadcasting station. Each of the push buttons I2, other than the push button associated with and controlling the switches I4 and I22, is adjusted in like manner to pre-set their associated controls to the desired ones of a selected group of broadcasting stations. when it is desired to use an already adjusted button for the selection of a different station, it is merely necessary to repeat the adjusting operation previously described.

In the form of the invention shown in Figs. 7 and 8, the switch unit 222 is mounted within a housing 224 to the rear wall of which is secured the tube 22 in the same manner as said tube is securedtotheplate 22 oftheformoftheinventhreadedrodflwhichconholsf the permeability settim ofthe adjiutable core 24and22. 'l'heopcratingrodfl'isin upon the insulating mounting plates I22 and I22. 4

Eachoftherods22'isprovidedwlthafrustoconical cam 2I4 engaged by a pivoted latch bar or strip 2I2 common to and extending transverselyofallofthe operatingrods 22'. Aspring strip 2I2 the latch bar and normally urga it into latching with the forward face of a depressed cam 2. A coiled spring 222 interposedbetween a partition wall 222 and a rear face of the cam normally urges the ted rod 22' to its forward position. It will be evident that upon depression of the selected rod 22' of the form shown in Fig. 7, the associated switch contacts 22, 24, I22, I22, Ill and H2 will be operated to connect the selected coils 24 and 22 to the tube 22 and the fixed condensers 22 and H4, and the cam 2, when in its rearward depressed position, will be engaged by the free edge of the latch bar 2I2 and held in said depressed position. Upon depression of another rod 22', the cam 2 associated therewith will cause the latch bar 2I2 to pivot vertically to release the cam 2 associated with the previously deprmed rod .and the spring 222 will cause said last mentioned rod to move forward into normal position.

It will be seen from the foregoing description that in the forms of the invention shown in Figs. 1 to 8 and 11, applicant has provided an automatic permeability tuner embodying a plurality of pre-settable tuning circuits in combination with a manually adjustable tuning circuit and wherein means, such as a plurality of push buttons, are provided for not only determining the selective connection of a pre-settable tuning circuit to the signal input of the tube 22, but also for adjusting the core elements of the coils forming constituent parts of the pre-settable tuning circuits.

In the form of the invention shown in Figs. 9, 10 and 12, the adjustable tuning impedances comprise trimmer condensers of the compression adjustable type. As shown in Fig. 12, the antenna 224 is coupled by a transformer 222, the secondary 222 of this transformer constituting the fixed inductance common to each of the presettable tuning circuits for the amplifier portion of the oscillator tube 22. One side of each of the adjustable condensers 222 is connected in common by a wire 222 in which is interposed a condenser 224, preferably of fixed value to one terminal of secondary 222. The other side of each of the condensers 222 is connected to a contact 222 of a switch 222, the other contact 242 of each of the switches being connected in common by a wire 242 to the other terminal of the secondary winding222andtotheconti'ol8rid22ofthe amplifying section of the tube 88. The adjustable unit 244 of the manually adjustable gang .condenser 246 is connected to the common wire 232 and by a switch 248 to the common wire 242. The common wire 282 is preferably grounded as at 258.

The anode electrode I84 of the oscillator section of the tube 88 is connected by a wire 282 through the primary 254 of the transformer 256 to the positive side of the B-supply source. The secondary 258 of the transformer 256 constitutes the fixed tuning inductance for the oscillator section. One side of each of the trimmer condensers 268 is connected in common by wire 262, in which is interposed an adjustable condenser 284 to one terminal of the secondary 258. The other side of each of the condensers 268 is connected to the contact 266 of a switch 288, and the other contact 218 of each of these switches is connected in common by a wire 212 to the other terminal of the secondary 258 and to the control grid I28 of the oscillator section of the tube. The adjustable unit 214 of the manually adjustable gang condenser 246 is connected to the common wire 282 and by a switch 216 to the common wire 212. The common wire 262 is preferably grounded as at 218.

As shown in Figs. 9 and 10, the trimmer condensers 238 and 268 are of the compression adjustable type and are arranged in pairs for common control by the threaded rod 28 which, similarly to the form of the invention shown in Figs. 1 to 6, is provided with a sleeve or collar 26 slidably received in the bifurcated member or portion 24 carried by or fastened to the rod 22 which latter carries at its outer end the push button I8. The switch unit 288 for selectively controlling the energization of the condensers 238 and 268 is similar in all respects to the controlling switch unit in the form of the invention shown in Figs. 1 to 6 with the exception that one of the fixed contacts of each of these switches is eliminated. The contact which is eliminated may be said to correspond to the contact 84 of the form shown in Figs. 1 to 6. The slide bar I66 which controls the switch unit 288 has its forwardly extending reduced end portion I18 pivotally connected as at 282 intermediately the ends of a lever 284 pivoted at its upper end to a bracket 288 carried by the front wall 288 of a bracket 288. The lower end of the lever 284 is twisted so as to lie in a plane perpendicular to the axis of the rod 22 and is bifurcated at its lower edge, the furcations thereof being received in an angular groove 282 in the bifurcated member or portion 24.

The adjustment and operation of this form of the invention will be apparent from the description hereinabove set forth in respect to the forms of the invention shown in Figs. 1 to 8.

It will be seen from this description that in the form of the invention shown in Figs. 9, and 12, applicant has provided an automatic tuner of the trimmer condenser type embodying a plurality of pre-settable tuning circuits in combination with a manually adjustable tuning circuit and wherein means, such as a plurality of push buttons, are provided not only to determine the selective connection of a pre-settable tuning circuit to the signal member of the tube 88, but also for adjusting the capacities of the trimmer condensers forming constituent parts of the pre-settable tuning circuits.

Further modifications and changes may be made in the form, construction and arrangement of the Parts without departing from the spirit of the invention or sacrificing any of its attendant advantages, and the right is hereby reserved to make all such changes as fairly fall within the scope of the following claims.

The invention is hereby claimed as follows:

1. In a tuning device for a radio receiver or the like having an amplifier, a plurality of individually tuned circuits, a plurality of separate means for connecting each of said tuned circuits to said amplifier to tune the receiver to a desired station, means for selectively controlling said connecting means, and means operated by said control means for varying the tuning of a selected one of said tuned circuits.

2. In a tuning device for a radio receiver or the like having an amplifier, a plurality of individually tuned circuits comprising inductances each having an adjustable core. element to vary the permeability of the core of said inductance whereby to vary the impedance of said inductance, a plurality of separate means for connecting each of said tuned circuits to said amplifier to tune the receiver to a desired station, means for selectively controlling said connecting means and means operated by said control means for selectively adjusting the core element of a selected one of said tuned circuits.

3. In a tuning device for a radio receiver or the like having an amplifier, a plurality of individua'lly adjustable condensers, a common inductance connected to said amplifier, a plurality of separate means for connecting each of said condensers to said inductance and to said amplifier to tune the receiver to a desired station, means for selectively controlling said connecting means, and means operated by said control means for adjusting the selected condenser.

4. In a tuning device for a radio receiver or the like having an amplifier, a plurality of individually tuned circuits, a plurality of separate means for connecting each of said tuned circuits to said amplifier to tune the receiver to a desired station, a plurality of push buttons, one for each of said connecting means, for controlling said connecting means, and a plurality of separate means each operatively connected to one of said push buttons for varying the tuning of a selected one of said tuned circuits.

' 5. In a tuning device for a radio receiver or the like having an amplifier, a plurality of individually tuned circuits comprising a plurality of inductances each having an adjustable core element to vary the permeability of the core of said inductance whereby to vary the impedance of said inductance, a plurality of separate means for connecting each of said tuned circuits to said amplifier to tune the receiver to a desired station, a plurality of push buttons, one for each of said connecting means, for controlling said connecting means, and a plurality, of separate means each operatively connected to one of said push buttons for adjusting the core element of the selected impedance.

6. In a tuning device for a. radio receiver or the like comprising an amplifier, a plurality of individually adjustable condensers, an inductance connected to said amplifier, a plurality of separate means for connecting each of said condensers to said inductance and to said amplifier to tune the receiver to a desired station, a plurality of push buttons, one for each of said connecting means, for controlling said conecting means, and a plurality of separate means each operatively connected to one or said push buttons for adjusting the selected condenser.

7.1natuningdevicetoraradioreceiverorth like, the combination of a plurality oi pro-settable tuning circuits, an adjustable tuning circuit, a plurality oi. switches for selectively rendering said pre-settable tuning circuits elective to tune the receiver to a desired one of a selected group of broadcast stations, an additional selectively operable switch, for rendering said adjustable tuning circuit eii'ective to tune the receiver to any broadcast station, a plurality of push buttons. one for each of the switches, forcontrolling said switches, and a plurality of adjusters operatively controlled by said push buttons tor selectively varying the setting or said pre-settable tuning circuits.

8. In a radio receiver or the like having a radio amplifier and an oscillator operatively associated therewith, the combination oi individually tuned pairs of tuning circuits, a plurality of separate for selectively controlling said connecting means, and means operated by said control means for simultaneously varying the tuning of each tuned circuit 0! the selected pair 01' said circuits.

9. In a tuning device for a radio receiver or the like, the combination of a plurality oi pre-settable tuning circuits, an adjustable tuning circult, a plurality oi switches for selectively rendering said pre-settable tuning circuits eilfective to tune the receiver to a desired one of a selected group of broadcast stations, an additional selectively operable switch, for rendering said adjustable tuning circuit effective to tune the receiver to any broadcast station, a plurality of push buttons, one tor each of the switches, for controlling said switches, a plurality oi adjusters operatively controlled by said push buttons for selectively varying the setting of said pre-settable tuning circuits, automatically operable means for latching the operated switch in its operated position and means operatively connected to said latching

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