US1707948A - Tuning system - Google Patents

Description

HQ F. ELLloTl April 2, 1929.

TUNING SYSTEM 5 Sheets-Sheet ...HMELH R m mE n@ N H w wh N fr M W l n Y uw N M HnH mQ .mm w .\\\\\.l l, QQ

BY w/ HIS ATTORNEY H. F. ELLIOTT TUNING SYSTEM April 2, l 19,29.

Original Filed Nov. 27, 1926 5 Sheets-Sheet. 2

N .lm-HHH 'April 2, 1929- H. F. ELLIOT-r 1,707,948

TUNING SYSTEM original Filed Nov. 27, 1926 5 sheets-Sheet 5 I .INVEN TOR Haro/d f.: f/bf/ HIS ATTORNEY PIE.. 4

April 2, 1929. H. F. ELLIOTT 1,707,948

TUNING SYSTEM origina Filed Nov. 27, 192e 5 sheets-sheet 4 HIS ATTURNEY April 2, 1929. -H. EELLIOTT 1,707,948

' TUNING SYSTEM x original Filed Nov- 27, 192e 5 sheets-sheet 5 me A-TonNEY Hafenfeenr; a, ieee. l

HAROLE E. EELroTT, errato AnTo, oenrr'onnra, .users-noia, EEn'rEEcT ann ivrEsnE AssIennEnTs, To vieron Tenants :anonima contreien, oE 'entrena'. NEW v JERSEY, a conrona'rroiton nEw .rEEsEn w Y n Teatina sasTEm. Y l

v l I l i A v f x i i r .application led November 2'?, 1926, Serial No. 15l,ll34. Renewed August 2t, i928. j f

rlhis invention relates4 to radio, and more A lurtherobjec't is -to provide a common 55 particularly to a systenrtor receiving radio factuato'rfor a plurality of tuners and'novel energ v means whereby movement of the common acln my prior application, Serial No. 119,1`14, Y tuator etiects simultaneous normal operation tiled lune 28, 1926, and entitled High frekof the tuners and individualb supplemental quency tuning system, L describe several' compensating adjustment of the tuners indecev forms of mechanical tuners, such as variable pendently ot the normal operation thereof..

condensers or inductances, whereby'a- ,plurality oi tunable circuits can be simultaneously tuned and kept in proper tuned relation with each other over the entire' range of .tuning. 'llhis was1 accomplished by they aid of; an element,`su'ch as a camY associated with each tuner, and havingian adjustable surface.

sothat the tuning characteristic ot the assomeans ciated tuner can be closely adjusted. f

As clearly explained in my lprior application many receiving systems include two or more tunable circuits Qconnected in tandem regular variations,

t 'be easily overcome.

A materially, over what is shown 1n the tuners from the adjustable cams.-

whereby the tuners mayv l relation in order to increase selectivity; and` prior proposals, based upon-mere simultaneous adjustment of the tuning elements, for securing simplicity oii operation, have been impracticable. rvrllhis results because it`is practically impossible Ito compensate for stray or parasitic capacities and inductances.

Another object is to provide a common actuating means-for a plurality of tuners includmg 'a' sultahle indicating device `and connections between said actuating means and tuners, the whole providing(varyingv increments oi movement of the tuners/ for equal. increments oi' movementl of the actuating such that the relation of the values ofthe circuitlin which the tuners are connect,A 705 ed to the movementof the indicating'device is substantially linear.

lit is `still* another object provide a compact,

d of my invention to inexpenswe receiving set.,

`lt is vStill another object ot my invention to provide a simple and novel tuning device that can be very quickly adjusted for coarse adjustment, and yet render it available at any time for fine adjustment.

My inventionypossesses many other advan- 8@ 'lfhe net result is a definite lossin sharpness,l tages, and has other objects whichu maybe the circuits not being accurately in alinement except possibly in one or two settings. l `By the aid of a cam. for operating each tuner, which ycan be accurately adjusted at the factory .for compensating for these virthese. dismlvantages7 can llt isa'n object of the present inventionto simplify thejstructu're y my prior application.

, This l am able to accomplish by-providing tion is best defined by the `only' one adjustable cam, compensating the.`

irregularities of all of the circuits, about vwhich cam .all of the tuners arearranged.

.Itis still another object ofjmy invention to T provide a novel and simple form of mechaf nism for operating the tuners.

Another, object-is to provide-novel means for effecting the compensating adjustment of A further object is to provide novel means be operated normally and a supplemental a ustment of the tuners i nsate for inequalithe tuners are-conj nectedr j j audits associated parts;

made more easily apparent from a consideras tion of several elnbodlments o my invention.' For th1spurpose l' have shown a :tewiorms in the drawings accompanying and forming:

detailed description is not to be taken ina 9o limlting sense since the scope of my invenappended-cla1ms.l

Referring -to the drawmgs :v

Figure l is @schematic Wiring diagram illustrating one form of receiving system in vv Which my invention can beincorporated g' Fig..2 isa vertical view, mainly in section,

ofa receiving set incorporating my invenalong plane .3 3 of Fig. 2;

'o Fig. is a top plan View of the receiver j with thercover and its associated parts vremoved, and some of the'p'arts broken away, in order lto disclose the structure clearly;

' I Fig. 5- is afragmetary top plan view of of thedial, v

the receiver, showing the form 1g. 3 is a horizontal sectionalview taken 100 frequency amplification by the aid of ther-4 Fig. 6 is an enlarged detail section, taken along plane 6-6 of Fig. ll; m

Fig. 7 is an enlarged detail section, taken along plane 7 -7 of Fig. 4e; and f Fig. 8 is a fragmentary sectional view of a modified form .of dial arrangement. In Fig. 1, I illustrate a conventional form of radio receiving system that can be made to incorporate my invention. F'Fhis system is used merely as an illustration of many other forms of systems that could as readily be used. It incorporates four stages ofi'adio inioiiic amplifiers, as well as a thermionic detector and two thermionic amplifiers operating at audio frequencies. rIhe number and arrangement of stages of amplification could obviously be varied. Furthermore, I indicate a neutralizing scheme for each radio frequency stage, in order to anniil substantially the effect of the parasitic capacity between the electrodes of the amplifier tubes, and thus to ensurestable operation; but obviously this too, could be modified or omitted. The important point is that such systems, of which this is typical, include variable tuning devices in some or all of the stages of radio frequency amplification, whereby selectivity is improved.

More specifically, there is indicated a conventional form of absorbing circuit, including antenna 21, vinductance 22, and a ground connection 23. Coupled to the'inductance 22 is a coil 24, which serves to impress upon the first radio frequency stage, E. M. F.s in,- duced iii it by the energy absorbed in the 'absorbing circuit. In order to amplify the signalingimpulses thus received, the amplifier tube 25is utilized, which is in the form of a sealed vessel evacuated to a high degree, and having therein several electrodes. One of the electrodes, suc-h as 26, serves as a source of electrons, which fiow --across the tube to another electrode, such as a plate 27. In order to cause electrode 26 to emit electrons, it is made in filamentary form, and is heated by current passed through it' from the source 28, such as a battery. The current ean^be vregulated to vary the intensity of electron flow, as. bv rheestat 29. Futhermore,n in

yorder that uplate 27 attract the electrons, it is kept at a potential positive with respect to the filament 26, by the aid of a source of uniform potential, such as battery 30. The

space current (that is, the current supported by the electronic flow in the tube space) has a completed ath, from the positive terminal of battery 30, through acoil 31, plate 27, vfila- .nient 26, and connection 32 back tothe nega- Ative terminal of battery 30. It is a well-known phenomenon that the intensity` of electron emission can be controlled by controlling the potential of a point in .thepath of thev electrons, and' this is usuallydone by the. interposition of a third aromas electrode 33 between the other two, serving as a controlelectrode. 'Ihis control electrode is usually in the form of a Lgrid;

Minute variations in the potential difference between filament26 and grid 33 cause Correspondingly larger variations in the space current and it is due to this feature that the amplification is secured. The large fluctuations in space current, passing through coil 31, sets up large E. M. F. iictuations utilized in succecdngstages. The E. M. Ffs existing across coil 24 are therefore impressed between the grid 33' and filament 26, whereby space current fluctuations in the output circuit of tube 27 are produced. As is eustomary, the filament 26 may be grounded, as indicated at 34. "f

In order to neutralize the effect of the capacity coupling between the plate 27 and grid 33, which coupling might otherwise cause the tube 25 to produce undesired oscilla coil 36, coupled magnetically to coil 31 in the output circuit. It can readily be `demonstrated that when such a circuit is properly designed, the E. M. F.s in the coil 31 due to the parasitic coupling, are neutralized therein. All this `is well understood, and is included `here merely for the purpose of completing the disclosure.

rlFhe description of the first stage ofvamplification is now complete. In this instance, succeeding stages are inductively coupled; and for this purpose, coil 37 is coupled to coil 31, these coils forming an air core radio frequency transformer. This coil serves `to impress an amplified E. M. F. uponthe input electrodes of the succeeding amplifier tube 38, the scheme of connections being' substantially identical as already described in con- 'nection with tube 25. lIhe filament is heated 'coil 37 or condenserll() is a maximum, and if the circuit is properly designed, this maximum is sharply defined, and-is very rapidly reduced even forslight departures from resonance conditions. It is this feature which'makes it possible, by ya series of tuned circuits," to provide a hig degree .of selectivity. The first input stage is in this instance also shown as tuned, as by the aid of condenser 55` bridging coil 24.

The succeeding .amplifier stages utilizing more@ tubes 411` and 42Jnay be coupled in succession in a manner entirely similar to fthat already disclosed. vEach stage includes' in'its input circuit, a variable condenser 43 or '44. Any

further number .of radio frequency stages p can if desired, be added; but since the princi-` i ple is thehsame, only four radio frequency stages are shown.

l The last stage ofradio frequency amplification is coupled to a tunable circuit 45`including the variable condenser 46. The detector tube 47 has its input electrodes connected across this condenser. It isfurther so arranged that it detects the signals,y by causing the audio frequency modulations of the -radio frequency carrier waves to replaceL vthese radio frequency waves. This process ,is well understood, and -can be @secured by proper choice of tube 47,' and usually by pro-- viding a small condenser 48 in the grid eircuit. A high resistance 49 is also rovided for assisting the detector action.y he output circuit for the detector'jstage e in this instance includes thiJ primary 50 of an iron cored audio frequency transformer,the secondary 51 of which serves to impress the detected wa'ves upon the'audio frequency amplifier stage formed by the tube52. Similarly,

further audio frequency stages may be added,

` but only one'additional one 53 is indicated. This last stagehas inits output circuit a .f translating device, such as phone or-loud speaker 54;

It is of courseevident that the number of stages, as well `as the arrangement of the coupling between stages, can be varied. It

.is sufficient for the present purposeV to point out that vthe system includes a plurality of tunable circuits, in each of "which there is 40 incorporatedya Variable tuning device, ex-

emplified in the present inst-anceby condensers 55, 40, 43, 44 and 46. These are. arranged to be 'controlled simultaneously, so as to bring all five tunable circuits into alinement by a 45 common means. Due to the high frequencies employed, even slight variations from simultaneous resonance of. these circuits', cause great loss in selectivity. i With my arrangement it is possi Ile tomaintain all such circuits in unifor resonance for their range.

In the present instance, the receiving apparatus, including the tubes, coils, condensers, and connections, are shown as housed in a. box having a bottom 56 (Fig. 2), sides 57, and a cover 58. The cover 58 serves as the main support for vthe parts. A main supporting member 59, made'from sheet stamping or a castin is fastened to the cover 58, vin a manner toie hereinafter described, and

60 provides a structure below the cover .upon

v which the eondensers, chils and tubes are supportedf Fig. 3 illustrates in a somewhat diaerammatic manner, a. possible arrangement of the elements on the bottom of support 59.

2 G5 'Upon this support there are appropriately fastened, a series of sector-shaped metallic shielding cans 60, disposed in a circlengFor the sake of simplicity, but one such can is shown in its entirety in Fig. 2. 't In the presentv lnstance, there are six cans, one'for each of the five radio frequency tuning devices, and one for the two audio frequency amplifiers 52 and 53 and their transformers 55. In

each radio frequency can there is a`compl`ete i radio frequency unit,vsuch for'example as tube 25, transformer 22-24, and condenser 55. Since the other cans contain eltirely .similarelements, it is not essential to describe lthem further; the can and its contents just referred to will, be described in detail and will serve as an eample of all of these cans. The elements`2522-24 are merely diagrammatically indicated, for their structure forms no part of my presentv invention. I

Each of the variable condensers 40, 43, 44, i

46, and 55 includes a pair of Asets of substaning elements 59 vin a manner to be hereinafter described. The rods 65 and 66 are connected by insulation strap 68, passing overV threaded ends of these rods, and held in place by nuts 69, 4which can convenientlyform the terminals of the sets of plates 61, 62; Coiled springs 70 are disposed over rods 65v .and-66 tending to 'v open the plate It is 'ofcourse understood that the .capacity l" of the condenser is varied byvarying-the re1- ative positions .of thesets 61, 62. On'e'manner in which this can be simply accomplished'is "indicated in Figs. 2, 3 and 6; 'An actuating l arm71 is fastened to tube 63, and a similar arm 7 2v is fastened to the other tube 6.4. -Links these arms, theother extremities of the links being fastenedto an actuator v75. One of the links passes above, and the other below the actuator, as indicated in Fig. 2; thus readily permitting both links to'be pivoted on a conimon pin f6.

` The operation of each of thether-con-"- denscrs 40, 43, 44 and 46 is likewise secured lby the aid ofthe same actuator' 75, and. sets of links 78, 79,y 80v and 81.- Tle actuator is in the l for-m of a disc, rotatable about a vertical axis, the links being connected near the edge of the disc,f as shown in Fig. 3. .Theselinks pass through apertures 85 in the cans.` vAs -viewed in; Figure 3, a clockwise rotation fof ,discv 75 will cause the condensers to close, and to' increase the value of their capacities. A counterclock-wise rotation will have theopposite effect, the sets of plates separating. Without* 11o- 73 and 74 pivotally connect respectively to ting a circular arrangement of the variable I tuners, the actuator for all of them being centrally located. This makes for compactness.; and since no gears or the like are used, there 1s no appreciable lost motion. Furthermore, lf find that the tuning characteristic can be made such as to give substantially a straight line characteristic for the curve connecting vthe extent of rotation of disc 75 and the frequency` of resonance. rllhis is due to the fact that equal increments of movement of disc 75 produce uneqal increments of movement of the condenser plates. B reason of this inequality of incrementsyt e operation of the variable tuners can be made such that a substantially linearfrelation exists betweenethe movement of th actuator and the frequency of resonance or the wave length, or between the movement of the actuator and both the frequency and wave length for respectively different portions of the range of movement of the actuator. 1^

The manner in which the disc actuator 7 5 is moved'will now be desoribed.v Support 59 has a large central vertical hub 82 in Ywhich is ,f

journaled a shaft 83. At the lower end of shaft 83 a boss 84 is provided, over which the disc 75 is passed. A screw 86' clamps the disc to the shaft. At the upper end of the shaft 83, there is earriedintegrally, a large wheel 87 ,s the section of which is `illustrated in Fig. 7 This wheel has an upper flange 88 that carries means for rotating the wheeland thereby the shaft 83.' Referring to Figs. 4V and 7, vthis means includes a pair of links 89 and 90 operating on opposite points. of a diameter of 'wheel 87.` Each link carries an ear 91 pivoted onba post 92 screwed into flange 88. A spacer 'l washer 93 separates each of the links from the fiange, and another washer 9 4 is disposed over each of the ears'and is held in place by screw 9.5 threaded in the post 92. The links connect,

f at their other ends, to oppositefextremitiesof a bar 96 pivoted on a in 97, held for example as. by driving, in a )oss 98 on support 59. This arm -is arranged to `be moved by lever 99, shown as of ribbed' construction, and' integral with arm 96.- This lever is arranged to be moved manually in amanner to be hereinafter described. It is sufficient forl the present to notice that as the pivot of arm 96 is back of the axis of shaft 83, the links 89 and 90 4stay parallel as this arm is moved about pin 97, but they move in opposite directions longitudinally, and thus serve to impress a torque couple on wheel 87.

In order to provide a stop for the movement y ered with resilient materlal 101 in the path of\ movement of arm 96. Furthermore, a washer 102 is disposed over the hub of arm 96 and lis held in place by screw 103, whereby said arm monete is held against vertical displacement on pin 97.

The description of the mode of operation of the tuning elements is now complete'. However, as explained in my prior application, it is impossible without some such arrangement as an adjustable cam, to aline the tuning ele- ,ments so that they remain exactly in step for theentire range of variation. Tn order to provide the compensation, the insulation bar support of each condenser is arranged to be movable. Considering Figs. 3, 6y and 7, it is evident vthat if bar 67 is moved about either of the axes of rods or 66, the relative positions of the condenser plates will be correspondingly varied, entirely independently of the movement of links 73 and 74. Only a slight compensating movement of" this bar 67 is necessary to keep the elements alined, but such movement should be adjustable over the entire range of variation of condensers 40, 43, 44, 46', and 55. It is now to be noted that disc 75 moves only a small portion of acompletfe ,revolution to operate the `condensers from `minimum to maximum capacity. Thus it is possible to support an adjustable cam structure on wheel 87 which has separate cam portions serving to operate bars 67 independently of each other.'

In the first place, eaclrbar 67 is supported on rod 65 -which passes through a stationary bushing 103 forminga bearing, in boss 104. An arm 105` is fastened to shaft or rod 65, at the other end of which/a cam follower roller 106 1s pivoted.` It is evident that a cam, actf ing on roller 106 will serve to move support 67 about the axis of rod 65.' Aspring'107 is fastened at one en d to support 59, and at the other end, to bar 67, whereby the rod 65 and its4 associated parts are urged in a ,direction to.

cause roller'106 to engage a cam surface.

The cam surface itself is adjustable, and

comprises@ strip 108 offlexible material,

such as sheet copper` or bronze. It is accomvmodated in a groove 109 in the periphery of wheel 87 (Fig. 7) and it extends an ularly a sufficient distance toalfect all live 'of` lowers 106 for the full angular movement of wheel 87. This strip 108 serves as a plurality of cams. The ends of the stripare connected by a tension spring 110 (Fig. 4). The radial positlon of each portion of the strip is adjustable by the aid of a plurality of adjusting set Ascrews 111 set in the rim of wheel 87, prefer-A ably at an angle to permit` ready insertion of a screw driver blade. Each f these screws has a round point contacting with the inner surface of the strip 1085 In this way, relative movement between the ser/ewsand4 the strip 108 longitudinally of the strip is permitted, to form a smooth continuous surface'.

It is evident thatl by'proper 'adjustment of those screws 111 which are immediately under the cam rollers 106` at any point of the range of movement of wheel 87, the rods 65 can all be moved slightly so as to bring all the tuned the fol# circuits intoresonance.J @ne cam structure, forming however a plurality of cam surfaces,

-is-all that is needed; and this structure -is substantially round, renderingit easy'iand inexpensive to manufacture. 'lhe screws 111 are set close enough.'A together to ensurecom-- `fully adjusted to bring all the condensers into 'alinemfent y I The supporting member 59 is provided with an inner flange 112 andan outer Hangs' I 113,1orming an annular space for accomm dating 'the Wiring, tired condensers, and other elements neededin the sy'srtemh A cover plate 11a isshown for this space in Fig. 2, but tor the `Sake of clearness, is omitted in Fig. Il. Furthermore, adjacent the lett hand portion oi@ support 59, there is an extension v115 upon which is supported aalterminal'block lltgexposed'through va window 117 or'permitting connections to be made tothe bat- Une .of these passes into boss 100 to coverv 58.

teries, loud ment-s.A t

The supporting member 59 is astenedto speaker, or other external elepasses through a `oit member 124, so that its tup surface isjust also to providefor a [to manner now to be described. A' shalt 133 large clearance aperture 13d inthe end of arm 99, and is pivoted at its bots tom bytheaid of pin 135. Illhis shalt carries an extension 136 on which ris journaled a tube 137, having teeth meshing with teeth 13,8 on the larger .arcuate edge of plate 119. 'llhis vtube is held against vertical displacement by washer 139 riveted over the end of extension 136. Knob 132 passes over tube 135'?y and is ightened in place therebn by set screw 140.v

t pivot 135 away from the teeth v138 bythe aid of knob 132,-'tube1137 can be disengaged from the edge of'aperture 121v and lever 99 can be quickly moved to any desired point. A dat spring 141 resiliently urges shalt 1.33 to. en-

gaging position. After this coarse adjustment is effected, the spring 141v can be allowed is evident that by moving shaft 133 on its 1 tu 'e 137 to move along the stationary edge ot aperture 121 in order to procure a tine' adjustthe cover 58 by several screws, such as 118. ment. @t course iittube 133 be made from andthe 'proper material, ,merely a trictional engageothers pass through a dial plate 119 (Figs. nient, without teeth, could be relied on for the 2 and 5) and into bosses 120 which are line adjustment of lever 99. Furthermore, it'

isentirely feasible then'to make shaft 133 lormed on support 59 and extend upwardly a t rigid and without pivot 135 or spring 1111.

There remains to be describe-@the dial al Under such circumstances, the coarse adjustrangement forindcating the setting of the ment can be eected by grasping knob 132,

apparatus. The dial plate 119 Has an arcuate and moving it without rotating it, in' the arc fro ` yclude a frequency scale 125, a wave length can be provided 'on member 121 to illuminate.

`cover v 58.

aperture, deiined by the inner surface l121 Prescribed by the axis ot'arm 99,`the smooth.

of .the rihon said plate. This-plate covers jouter surface or' tube 137 slipping along the a substantially coextensive aperture 122 inV 'edge 0f the aperture. For line adjustment, Through apertura. 121 @an be the knob can be turned, .providing a trlctlon lsighted a scale 123 on a member 12d fastened gaat mOi/'ement'.

on the bottom of cover 58.4 rllhis scale can in: @ne or more small incandescent lamps 1112 scale 126, and a clear space between these the scale, and can behidden by dial plate 119.

vscales upon which stationcall letters can be written. A transparent pointer or indicator lengtlrscale 126 isp'roportional; and by propl27vis-arranged to sweep over these/scales as er design either'th1s scale or the frequency v vthe tunerV is operated. 1t has .a main slot 128 scale 125 can be made proportional. 'llhis is and narrow end slots 129the former for per'- rendered possible vby the particular mecha- I described, it is merely necessary to bring indi -niittingcall letters to be written on scale 123, nismfused tor setting the condensers 110, 43, and vthe latter for permitting arshort mark M, 16. and 55, that cause the condenser setto be drawn corresponding. to "the "e `letters. tingst be unequal for equal settings of actua- 'l`o` obtain any such setting marked as thus tor arm 99. y

cator 127 insuch position thatl is located' above the set.. Suc an arrangement slot just exposes the'mark. v. .y l l e e i A The indicator 127 is of oourse'earried by sect1on of lhg. 8.- `lln tins form, the support arm 99, so that as this-arm is moved, the indi;f 59 and cans (i0 are shown 1n a position that 1s the narrowln the embodimentjust described, the scale.

`\\ is shown in the 'diagrammatic fragmentary I Y llt] llt will be noted in Fig. 5 that the wave.

izo

. catormoves also."v rlh'is indicatorwis fastened, just reversed,ythe actuating armf143 (correy free extremity oit` lever 99. This boss131 However, the .mechanical arrangement is extends 'into aperture122 Vand pastjthe *edge identical except tor reversal.. The right as bya pair of screws 130, to a boss 131 at the sponding to arm 99) being below'fthe support.

f hand portion of thebabinet has anapertured dial plate 144. This' plate is circular about a vertical axis coinciding with that of arm 143.

` The stationary scale plate 145 is correspondingly curved, and is exposed to view through plate 144. The pointer 146 is fastened to the front portion of lever 143 and is closely spaced with respect to scale 145. -The lever 143 has anl extension 147 on which is supported a turning knob 148,`arranged to coact with the bottom edge of the aperture in p late 144 to se-l cure a fine adjustment.A 'llhis knob can be supported in a manneranalogous to that used in connection with knob 132, in order to permit disengagement of it with respect to the edge of the aperture and thus to secure coarse adjustment.' rll'he operation is analogous to said condensersbeing angularly spaced about l an axis, an actuating disc rotatable about the said axis, and pivotally joined'v link connections between the condensers and the disc for causing movement of the condenser plates.

3. In combination, a pair of sets of plates. each movable about an axis that is'spaced from'the axis for the other set, a crank arm for each set, and pivotally joined links for operating said arms. i

4. ln combination, a plurality of tuning devices, a movable element for each device whereby the devices can be operated, all\ of said elements being angularly spaced about an axis, and a cam structure rotatable 'abut the axisand operating all of said movable i elements. f

5. In combination, a plurality of tuning devices, a movable element for each device lwhereby the devices can-be operated, all of said elements being angularly spaced about an axis, a wheel rotatable about said axis, a flexible strip extending around at least a portion of said wheel, and means for adjusting the radial positions of points on the strip, for providing an adjustable cam structure, said i movable, elements being operated by said cam.

- 6. In combination, a plurality of variable condensers angularly spaced about an axis,

each of said condensers having a pair of electrodes pivotedfor relative motion on spaced `axes,a common supportfor both electrodes of each condenser, an actuator,E rotatable about the ax1s for causing relatlve motion of ,said electrodes, and an adjustable cam structure arranged to be rotated in unison with the ac-A tuator for supplementing the setting of the condensers.

aren-@eee 7. ln combination, a plurality of variable condensers angularly spaced about an axis, each of said condensers having a pair of electrodes pivoted forrelative motion on spaced axes, a common support for both electrodes of each condenser, an actuator rotatable about the axis for causing relative motion of said electrodes, and an adjustable ycam structure arranged to be rotated in unison with lthe actuator for compensating the condenser-s for inequalities, said-cam Operating to move the electrode supports relatively to the actuator for effecting this compensation.

8. ln combination, a support, a shaft journaled in the support, aplurality' of variable condensers supported on one side of the support, and angularly spaced around the shaft, a pivotally joined link connection between I each condenser and the shaft, and means on the other side of the support for rotating the shaft.

connections between the shaft and the cle-l ments for varying them, and au adjustable cam structure fastened tothe shaft and located on the other side of the support, for

imparting a supplen'xentary adjustment to` the elements.

10. lln combination, a support, a shaft journaled in the support, a plurality of tun- `ing elements, each having relatively movable parts, supported on one side of the support and angularly spaced around the shaft, a connection between the shaft and each element for causing rotation of the shaft to vary the elements, an adjustable cam structure rotatable with the shaft and on the other side of the support,l and meansoperated by the cam to adj ust'the relative )osition of the elements and the shaft, where ya supplemental adjustment is edected.

11. In combination, a support, a shaft. journaled in the support, a plurality ofvariable condensers having relatively movable electrodes, a bar for each condenser upon which the electrodes are supported, a rotatable pin associated with each bar and fas tened thereto, said pins passing through the the other side of the support, said wheel having a groove in its periphery, a flexible strip in said groove, screws passing into the groove for adjusting the form of the strip and there` by providing an adjustable cam surface, and means whereby rotation of said cam surface moves the pins and causes the electrodes to be supplementarily adjusted. 12. ln combination, a lever pivoted adjareleases f cent one end, a tuning device operated by said lever, a scale, an indicator carried by the lever and cooperating'vvith the scale, a plate having an aperture^through which the scale is visible, a rotatable knob carried by the lever adjacent the indicator, a Wheel rotated by said knob and engaging the edge ofthe aperture for providing lineadjustment, and yielding means for maintaining the Wheel in contact With said edge. y ff l 13. ln combination, a pivoted lever, a tuning device operated by said lever, a pin extremity of the lever,

pivoted adjacent oneJ a rotatable sleeve/carried Iby the pin, a plate having an aperture the edge of which is arranged to be engaged by thesleeve, and yielding means` for, urging the pin in a direction to engage the sleeve aiid/ the edge.

14. ln combination, a pivoted lever, a

tun-

ing'device operated by said lever, a scale ar-l ranged: adjacent the free end ot the lever,

ried by the timing devices angularly spaced from each an indicator carried by the lever, a stationary plate over thescale, and means forming a disengageable rolling connection'between the end of the *lever vand said plate, whereby coarse adjustment is eected when said connection is disengaged, and tine adjustment when said connection is engaged.

15. lin combination, ing device operated by said lever, a scale ai'- ranged adjacent the free end of the lever, an indigzator carried bythe vthe tuning device, lever, forming a: disengageable rolling connection between the end of the lever and a portion of said housing, comprisinga knob, a pin carlever, a sleeve carried by the knob and. rotatable on the pin, a portion of the periphery of said sleeve being arranged to contact With the housing, and means forresiliently urgin the pin sog as to move `,the sleeve into rolling engagement. l

16. 1n combination, cent one end, and a scale cooperating with the Vfree end of the lever, a tuning device having a rotatable wheel pivoted on an axis spaced from but parallel to the lever axis, and a pair of links connecting the Wheel and the lever, whereby movement of the levefrn'causes corresponding movementY of the Wheel.`

17. lln combination, a plurality of variable other around an axis, a common support for all of said devices,

vices simultaneously, and metallic shields supported on said-common support, enclos- I ing'and segregating each of said devices.

p device,

18.y ln combination, a plurality of variable 'tuning `devices angularlyspaced from each otheraround anaxis, a comgnon-support for allot-said devices', a metallic shield foreach allv of said shieldsbeing supported on the common support, and leaving an' open space adjacent the axis-,and an actuator ro.

Aments, and 'means for simultaneously a pivoted lever, a tunf lever, a housing for and scale, and means a lever pivoted 'adj a.

ant actuator rotatable"- about the axis for operating all of said detata-ble about said axis and located in -said space, said actuator serving to operate all of said devices,

19. ln combination, a plurality of tuning devices, a movable element for each device whereby the devices can be operatcd,-all vot said elements being angularly spaced about an axis,.a wheel rotatable about the axis, and a flexible strip carried by the Wheel for operating said movable elements.

. 20. ln combination, a series of tuning dcviccs each having relatively movable eleoperating all of said devices, including a rotatable support, and a flexible strip resiliently held on the 'support but 'not rigidly attached thereto.

21. ln combination, a lever pivoted adjacent one end, a tuning device operated by said lever, la scale, an indicator carried by the lever and cooperating with the scale, a plate l Yhaving an aperture through which the scale in visible, a rotatable knob carried by the lever 2Q. lin combination, a pivoted lever, a tun- ,ing device operated by said lever, a pin piv- V oted adjacent the free extremity of the lever, arotatable Sleeve carried by the pin, and a plate having an apertureitlie edge of Which is arranged to'be engagedv by the sleeve.

A 23. lin combination, a lever pivoted adjacent one end, a scale cooperating with the free, end of the lever, across arm carried by the lever, a tuning between the cross arm and the device.

device, and connections y24.. 1n combination, a lever pivoted adjal cent one end, a scale cooperating with the free end of the lever, a cross arm carried b`y lthe lever, a link pivoted at each end of the cross'arm, and a rotatable tuning-device actuatedby the links.

25. ln combination, cent one end, a scale free end of the'y lever, a cross arm carried by the lever,4 a link pivoted at each end of the cross arm, a rotatable member to whichthe a`- lever pivoted adj aor` more tuning devices operated by the rotatable member. Y

26. In combination, al timing device, a rotatable actuator for said device, a lever for moving the actuator, a scale cooperating with the free end of the lever, and connections between the lever and the actuator, said concooperating with theother ends of the links are connected, and one nections being such that equal increments v of movement of the 'lever cause unequal increments of movement of the actuator. 27. ln combinationfa tuning device, a rotatable actuator l moving the actuator, a scale cooperating .ivith the free end of the lever, and connections be'- tween the actuator and the tuning device,

,Well as between the actuator and said leve-r,

for said device, a lever for` arran ed to produce movements oit' the device the free end of the lever, and linkages between the lever and the actuator, and `bewee the actuator and the tuning device. A

29. lln combination, an actuator having an axis `of rotation, means providing. an axis of rotation parallel to but spaced from that oit saidfactuator, a scale concentric with said lat` ter axis, a member movable about the latter axis and cooperating with the scale, a link connection between said member and the actuator, and one or more tuning devices operated by said actuator.

y30. ln combination, an/actuator having an axis of rotation, means .providing an axis ot rotation parallel tof--b'ut spaced from that ofsaid actuator, ascale concentric lwith said latter axis, armember movable about the latter axis and cooperating with the scale', a connection/between said member and actuator such as to cause disproportionate movements thereof, Iand one or more tuning devices operated by said actuator. j

31. lin-combination, an actuator having an axis otrotation, means providing an axis of rotationparallel to but spacedfrom` that of said actuator, a scale concentric with said latter axis, a member movable about" the latter axis and cooperating with .the scale, a connectiombetweemsaid member and actuator such as to cause disproportionate movements thereof, one or more tuning devices, and connections between said actuator and the tuning devices such as-'to cause disproportionate movements thereof.

32. In combination, a variable tuning'de- :iguanas one ot saidcrankharms, and a `rotatable actuator, the outer ends of each pair of links for each pair'of sets of plates being pivotedto said actuator at a coinmon point, whereby rotation of said actuator causes relative movement of each pair ot sets oit movable plates.

y36. ln combination, a plurality of variable tuning devices each having relatively movable members, an angularly adjustable support for each device, a rotatable actuator, an operating arm tor each support operatively engaging said actuator, whereby rotation ot said actuator causes angular movement of each support and its device, and means whereby said angular movement causes relative movement of said members.

37. lln combination, a plurality of vai'iable tuning devices each having relatively movable members, an -angularly adjustable support tor each device, a rotatable actuator, adjustable cam means on said actuator, an operatingarm :tor each support operatively engaging said cam means, whereby rotation of said actuator causes cam-controlled angular movement of each support and'its device, and means whereby said angular movement causes relative movement of said members.

3S. lli combination, a plurality of variable tuning devices eachv having relatively movable members, an angularlyV adjustable support for each device, a rotatable actuator, means whereby movement of said actuator causes relative movement of said members, and an'operating arm for each support operatively engaging said actuator andl causing -angular adjustment of its support on movevice having relatively` movable members, am

angularly adjustable support for the device, the angular adjustment thereof being on an axis transverse tothe movement of the members, an `actuator for moving the -members relatively to each other, and means whereby the actuator causes angular movement of the supportrso that the relative moveine/nt of the members is supplemented.

33. The combination as set forth in claim 32, in which means are provided for adjusting the extent of tliegangular motion -upon a delinite movement of the actuator. p

84. In combination, a rotatable actuator, a plurality of variable condensers positioned radially about said actuator and each having a pair ot sets of movableplates, a crank arm for each set of plates, and a plurailty of pivotally joined links each connecting one of said arms with said actuator.

35. ln combination, a plurality of variable condensers each having a pair of sets of movable plates, a crank arm' for each set of plates, a plurality of links each pivoted to ment of said actuator, whereby al supplemental relative movement ot said members is produced. i

y 39. ln combination, a plurality of variable tuning devices each-having relatively movable members, an angularly adjustable support for each device, arotatable actuator, means operatively connecting said actuator w' h-each device to cause relative movement o said members on 'movement of said actuator adjustable cam means on said actuator, an an operatingy arm for each support operatively engaging said cam 4means to adjust said supports angularly on movement of said actuator. f y y 40. In combination, a )pluralityy of variable tuning devices 'each having relativelymovable members, an angularly adjustable support for` each device, a rotatable actuator', pivotally joined links connecting said actu-r ator withsaid members, canfmeans n said actuator, and an operating arm for each sup- Iport 'operatively lengaging); said cam means.

4l. In combination, a plurality of variable iio` tuning devices `angularly spaced from each other around an axis, an actuator rotatable abput the axis, pivotally joined link connec Monete on said actuator, and means operatively connecting sald cam means and sald devices vfor `Vsupplementarilyv operating said devices.

ing movement of the condenser plates, ad'

justable cam means on the disk, and operating armsnterposed between the condensers and the cam means for causing supplemental movement of the condenser` plates.

43. ltn combination, a plurality of tuning`v devices,` an actuator` for said devices, means including an indicator arm for moving said actuator, and connections between said actuator and each tuning device causing unequal increments of movement of said tun-v ing devices for equal increments of movement of said means, whereby the relation between the values oi the circuits to be tuned and the movement of the indicator arm is substantially linear.

ln testimony whereof ll have hereunto set my handa Hanoi@ r, nnniorr,

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