US2196147A - Coil system - Google Patents

Description

April 2, 1940. w. L. DUNN coir.- SYSTEM Fild Jan. 11, 19:57

2 Sheets-Sheet 1 w Wm uwn Dun. LE

ts-Sheet 2 Patented Apr. 2, 1940 COIL SYSTEM WilliamLDunn,

Chicago,

Ill.,a-ignorto Belmont Radio Corporation, a corporation of Illinois Application January 11, 1937, Serial No. 120,047

4 Claim.

This invention relates to coil systems for radio 'eceiving sets or the like, and particularly to such :01] systems as are adapted to be constructed leparately for inclusion in a radio set as a unit. ['hese units have been illustrated as including nductively coupled coils together with trimmer :ondensers therefor, connecting lugs for con- :ecting said coils to other parts of the circuit, ind a base adapted to have mounted thereon any me of a variety of different coil structures and :he condensers and connecting lugs for each.

All of the features of this invention are of gen- :ral utility, but some of them are of especial value in connection with the so-called multiband radio receivers. In such receivers it is common practice to provide one or more primary coils and a different secondary coll for each band of wave lengths or frequencies which the receiver ls designed to receive. If all of these coils are mounted into a single unit, the entire unit must be rejected when one coil thereon is defective, and hence the number of rejects is relatively large. There would be the fewest number of rejects if each secondary with its primary formed a separate unit so that one unit could be rejected without the others. This results in excessive material costs, however, and the most economical arrangement therefore is to place the coils for at least two bands in a single unit with the result that in a three-band receiver, two units will be necessary.

In order to keep the material and production costs as low as possible, and yet maintain a highly eillcient operating level for the coil system, it is necessary in such coil systems for the multiband receiver to consider not only the question of rejects of coil units, but the assembly of the units themselves, the assembly of the entire coil system. and particularly the actual testing and inspection operation.

In most eiiiciently taking care of all these factors, there was the problem of providing all elements of the system capable of rapid assembly into units and into the coil system. providing them to perform as many functions in the complete apparatus as possible. and at the same time eliminating or minimizing undesirable capacities, and inductances in the circuit of the coil system. as well as having those elements act to speed up inspection and reduce breakage and reiects. Inasmuch as variations in the particular coil assembly might be necessary for each band of each particular type of multi-band receiver, itwas desirabletohaveauniversalbaseof insulating material which would take any one of such various assemblies. The connecting leads in high frequency circuits may introduce an appreciable and undesirable inductance in the circuit, and it was therefore desirable to have connecting leads in the complete coil system as short as possible. While it was desirable to provide variable capacitors across each secondary of the coil system to adjust the circuit capacity at the high frequency end of the bands to a uniform value, it was likewise necessary to maintain stray capacity of all components to ground in the entire coil system at a minimum. In providing terminal members both for general wire connection, and for the variable capacitors of metal in a stamped out construction extending through the assembly base, undesirable inductance and circuit capacity is minimized, while the single shield of large perimeter of the present invention, has the most beneficial effect so far as the coil dissipation constant is concerned. Where previously in making inductance tests particularly, on coils, one or more wire ends were placed into spring contacts in the testing jig, the present construction now makes it possible to eliminate this added handling and danger of breaking wires, inasmuch as the lugs alone effect all the necessary circuit connections in the jig.

According to the present invention, therefore, the receiver is provided with two detachable bases, each adapted to have a coil unit mounted thereon, but in the interests of economy these bases are identical, and in the interests of ease of mounting, each of them is secured to the chassis by a single screw. It is understood, of course, that more than two bases may be employed as the system is adapted to receivers of increasing numbers of wavebands. The coil system of the present invention, as illustrated and described, provides a complete coil'assembly sufflcient for at least a four-wave band receiver circuit, all covered by a single shield. This single shield has the double advantage of reducing material costs and increasing the coil dissipation constant which in general is increased as the perimeter of the shield is increased. Furthermore, the coils themselves are small piwsically with relation to the shield, thereby increasing the spacing between the coil components and the shield, and reducing the stray capacity at this point to a minimum.

Since the base is to be identical for different coil units, it is formed with suitable apertures for mounting thereon, any one of several specifically different coil assemblies and associated terminal elements as such unit. This of course is desirable whether two different units are to be used in one set or not, so that the same base may be used with difierent coil structures even in diiferent receivers. In using two identical bases in juxtaposition in one set, there is a special problem in providing compactness of arrangement together with ease of mounting the bases to the frame. For compactness it is of course desirable to have a single cut-out opening through the chassis, at which opening both the bases are to be secured; and it is likewise desirable that the bases fit snugly against one another, and that no space within the opening be wasted. Accordingly, the identical bases are made with the securing aperture at one side thereof, and one of the bases is inverted for assembly of the elements on it so that the securing holes are positioned at the far sides of the two bases as used, thus making it possible to mount the two coil units against the receiver chassis frame at the edges of the bases while lugs on the bases extend through a hole in the chassis under which the coil units are positioned.

A very important feature of the present invention, both from the standpoint of convenience in connecting the coils with the external portions of the receiving circuits and from the standpoint of minimizing stray capacity and other losses, is the provision of connecting lugs which are secured to the base and extend therethrough so that the external wires may be connected on either side of the base, rather than extend through the base. This feature is utilized throughout the coil units including the lugs on the individual coil forms, the trimmer condensers and the separate connecting lugs. One reason it is important to minimize stray capacities is to obtain reception over any desired range of frequency with the smal'est possible number of coils. The use of a large shield encircling the coil system contributes to this result.

Inasmuch as the trimmer condensers and connecting lugs pertaining to each coil form are mounted on the base to which that form is se- 1 cured, the coils may be connected thereto before assembly of the units in the receiving sets. Furthermore, because of the fact that the standard perforations of the base insure uniformity of positioning oi the connectors with each type of coil unit, testing of the coils is greatly facilitated by virtue of the fact that a testing jig may be provided with spring contacts for each corresponding aperture in the base so that it is merely necessary to place the entire coil unit thereon and the proper test connections will be automatically connected, depending on the particular terminal arrangement in the apertures on that base.

The objects of the invention are mostly apparent from the foregoing description of the special features and advantages. Further objects and advantages will be apparent from the fol lowing description and from the drawings, in which:

Fig. 1 is a horizontal sectional view of the form of this invention chosen for illustration, showing a plan view of the coil assemblies in substantially twice actual size.

Fig. 2 is a bottom view of the structure shown in Fig. 1.

Fig. 3 is a vertical sectional view showing the coil assemblies in elevation.

Fig. 4 is a fragmentary sectional view of one of the connecting lugs.

Figs. 5 and 6 are fragmentary sectional views taken respectively on the lines 5-! and 8-4 of Fig. 2, and showing the trimmer condensers.

Figs. 7, 8 and 9 are views indicating the manner of forming respectively the connecting lugs, the fixed condenser plate, and the movable condenser plate from single pieces of metal.

Figs. 10 and 11 are fragmentary circuit drawings showing the connections provided in the coil assemblies; and

Fig. 12 is a view of a modified embodiment illustrating fragmentarily a coil system with more two coil units.

Although this invention may take numerous forms, only one has been chosen for illustration. In this form, the invention has been illustrated as associated with a frame or chassis l I of a radio receiving set. This chassis is provided with an opening l2 therethrough of generally rectangular shape. Securing lugs II on the chassis may project into the general outlines of the opening l2. A pair of insulating bases II and HA are secured below the chassis II by means of screws I6 passing through suitable perforations in the bases l4 and HA and threaded into the securing lugs [3.

Above the frame H a shield I8 is secured, this shield surrounding the entire opening I2 and consequently substantially the entire areas of the insulating bases. The shield may conveniently be secured by means of a pair of securing studs riveted thereto and passing downwardly through the frame II and through holes formed between the two bases H and MA as shown at is. These last mentioned holes may be formed by the provision of semicircular notches in the edge of each base. The shield i8 may be provided with an aperture 2i at the top thereof through which a grid clip 20 (Fig. 3) may be passed for connection to a tube requiring an external top connection.

From Figs. 1 and 2 it would appear at first glance that base H and base A are different, one being adapted to fit at the left-hand side of the opening I2, and the other at the right-hand side thereof, as seen in Fig. 1. As a matter of fact, however, these bases are identical, the necessary result being obtained by positioning them with their opposite faces up, thus making it possible to stamp out only a single form for all bases, yet use them either for the coil unit for the right side, or that for the left side in the two-unit assembly of Fig. 1.

A modified embodiment is illustrated in Fig. 12, in which more than two coil units are provided in the complete coil system. Identical bases B are mounted at an opening in a chassis H by means of screws through holes at the top and bottom of each base B extending into mounting lugs l3 on the chassis at the opening. Coils C, D, E, F, with one mounted on each base, are illustrated somewhat diagrammatically. It is understood of course that the number of individual coil units may be varied in accordance with the number of wave bands for which the receiver is designed.

From Fig. 3 it will be seen that two different coil forms are provided. As a matter of fact, there may be several other forms than those shown. In general, however, they will comprise a solid dowel 23 which may be either of ceramic material or wood, on which coils 24 and 25 are wound, or a tube 26 on which coils 21, 28, 29 and 3|! may be wound. The solid dowel such as 23 may be secured to the base It (or HA) very easily by means of a screw 32 passing through hole II in the base and screwing into the bottom 7| 0,198,, I g I I w 3 of the dowel. To prevent the dowel from turn-- ing, a lock washer 33 may be desirably positioned between it and the base I4, and for that purpose the base It is provided with small apertures 34 into which special projections on the lock washer may flt. while projections in the opposite direction project into the dowel.

The tubular coil form 2| may be secured in a somewhat similar manner (not shown) by hav- 9 ing its lower end flanged over and a washer inserted down through the tube 20 to be secured to the base by a screw or by an eyelet. However, it is preferred inaccordance with this invention, to provide the tube It, which may be formed of w any desirable insulating material, with a plurality of combined connection and attachment members 36 secured to the lower end of the tube. These members 38 include flat connecting and securing lugs 31 projecting downwardly from the I) tube 26 and through correspondingly shaped apertures a in the base A. The lower endsofthelugsllaretwistedtostandina plane crosswise of the apertures it as seen in .Fig.2soastobindtheluss theslotsand Ilockthetubeflinplaceon lugs also facilitate testing ofthe coll before is assembled on a base It or they will slip directly into spring contacts in a testing jig. The members It also include outstanding lugs It so that connections can be made to them above the base A as well as below.

l 'roml igslandzitwillbenotedthat grouped around the securing hole 3| ofeach base (i. e. around the coil forms) are a plurality of It pairsof aperturesinthebase,eachpai rincluding a small slot, ll and a circular opening 4!.

These are provided for connecting lugs, some of which have been shown in place. These connecting lugs each include an upstanding solderm ing lug 46, a downwar ly extending soldering lug l1, and a securing base 48, of which ajportion is extruded to form an integral eyelet 40. In the preferred form of the invention, the soldering lug 46 extends through a slot 4|, while will be apparent that by bending the soldering lug 46 in one direction and the soldering lug 41 in the other direction about thedotted line Ii, the finished connecting member will be formed .asshowninl"ig.4,whichalsoshowshowitis securedtothebase llbyupsettingtheeyeletll. Bothofthesesolderinglussmaybeprovided with perforations I! to facilitate securing a wire thereto, if desired. However, the soldering lug l'lmaybeshortenedasatl'l'inFigJtoomit the perforation 52. In this case the projections 63 formed by 'cutting out the lug 46 will tend to help hold the wire in place during soldering.

As seen in Figs. and 11, atrimrner con- 53 denser 56 is desirably connected to each ofthe secondary coils 25, 21 and 20. Thus, on the base A, on which two of the secondary coils are mounted, there will be two trimmer condensers whileonthebase Iltherewlllbeonetrimmer m condenser. Since two trimmer condensers will be desired on some bases, the bases are still provided with suitable perforations for these condensers, these perforations being those shown in the lower portion of Fig. 1. n The structure and eat of the condensersisshownbestinl'igsJandfiwithrefq erence also to Figs. 8 and 9. h denser plates is stamped out of a single sheet of metal, as seen in Figs. 8 and 9. condenser plate Cl is provided with a securing s aperture 02 through which a rivet is passed to secure it to the base It or "A by a rivet 03. It is also provided with lugs 64 and 5 which are respectively bent upwardly and downwardly about the dotted lines 80. The upwardly bent to lug 84 passes through a slot in the base It, thus determining with the rivet 83 the position of the plate II and preventing rotational movement of the plate, and also furnishing a soldering lug above the base ll.

The movable plate II is of a more complicated structure, being provided with the integral resilient loops I2 bent from the plate II at the dotted line II. At the far ends of the loops 1! a transverse web ll is provided from which is bent a securinglug 'llwhichisflrmlysecuredtothe base II by a rivet 16. The loops I: are continued to form lugs 11 which both pass upwardly through slots in the base It and together with rivet it properly position and hold the conas denser plate II on the base.

Theloops'llareresilientandbiasedinadirection to move the plate ll away from the plate II. a mica plate II or ,any other good dielectric insulatingly separates the two metal plates and so is retained against the fixed plate 8 by the rivet CI therethrough and the rivet ll securing the movable plate II on the base (Figs. 5 and 8). Plate II is moved towards the plate I for adjustment of the capacity of the condenser by a 88 screw It passing through a hole II in condenser plate II. An enlarged hole 82 is provided in fixed condenser plate ii so that it will not make contact with the screw II, which screws into the base ll. The plates II and II are of course receaed wherever to prevent contact with the rivets for and connected with the other plate,such beingseenat8landfl.

Fromtheforegoingitwillbeseenthateach condenser plate has at least one contact above thebase l4 andonebelomandthatallofthe' other connection members are likewise provided with a connecting portion above and a connectingportionbelowtheplates. Thismakesitentirelyunnecessarytohaveanywiresextending throughthebasellorllAandhence'thecom' stantsofthecoilscanbepredetermincdvery accuratelysincethecoilsmayalwaysbeconnected to connecting lugs with minimum lengths of wire positioned entirely above the bases, thus 5 preventing excessive inductances in the current due to long leads. In fact, in some instances, as at A (Fig. l), the lugs are of such length, and so positioned, that two lugs may be soldered togetherratherthanrunawirefromonetothe other. At connection A 9. lug 84 from the sta- 'tionary plate of a trimmer condenser is connectedtoalugflc rryinsaleadfromthecoil 21. The wires connecting the coil assembly with external portions of the circuit will usually be 65 connected below the bases, and of course a band selector switch will be provided for connecting the coils to be used.

Although the invention has been described in its preferred embodiments, it is understood that various specific coil assemblies and systems may be provided, all utilizing the present invention, and it is not limited thereby but is limited only by the scope of the appended claims.

I claim:

1. In a radio receiving set, a chassis having a relatively large opening therethrough, a pair 01 identical bases differently disposed with reference to one another secured to said chassis at said opening by securing means at an outer edge of each base and having formations therein for mounting parts of a coil system on the portions of the bases which are exposed through said opening, with said bases being mounted at said opening with an inner edge of each in abutting relation but with the securing means therefor being such that each base is mounted independent of the other and a separate coil form together with connecting means for all terminals of the coils thereof mounted on each of said bases whereby each of said units including coil form, connectors, and base, may be accepted or rejected and replaced independently after test.

2. In a radio receiving set, a chassis having a relatively large opening therethrough, a pair of identical bases difierently disposed secured to said chassis at said opening at an outer edge of each base and having formations therein for mounting parts of a coil system on the portions of the bases which are exposed through said opening, with said bases being mounted on said chassis in edge to edge relation but independently of one another, a separate coil form together with connectors for all terminals of the coils thereof mounted on each of said bases whereby each of said units including coil form, connectors, and base, may be accepted or rejected and replaced independently after test, and a shield surrounding both of said coil forms and secured to said frame.

3. Apparatus of the character described including in combination a metal radio receiving chassis having an aperture therein and a coil system secured to said chassis at said aperture comprising a pair of insulating bases positioned in abutting relationship at one edge of each base, and such bases together having a. perimeter greater than the aperture in said chassis so as to over lie the aperture and extend together beyond the edge of said aperture whereby to be supported on said chassis at said aperture edge, each of said bases adapted to be secured directly to said chassis adjacent the aperture with the securingoteachbeingatapointspacedfromthe abutting edge, a coil mounting supported on each insulatingbaseandacoilonssidmmmting,a condenser secured to each base, contact means for said condenser extending to each side of said base for electrical connection with said coil on one side and for receiving on the other side electrical connections from the radio receiver, with said two bases with the elements thereon being independently mountable and removable so that each base with its associated elements may be assembled, tested, and serviced independent of the other, and a single shield surrounding the elements on said two bases having means thereon for securing said shield to said chassis at said aperture with said securing means acting to also secure said insulating bases to said chassis.

4. ,Apparatus of the character described including in combination a metal radio receiving chassis having an aperture therein and a coil system including a pair of coil units secured to said chassis at said aperture, each of said coil units including an identical insulating base having a coil mounted on one side thereof, contact lugs for said coil having portions extending entirely through said insulating base for receiving wire connections on each side thereof, with the wire connections on one side extending to said coil and on the other side extending to radio receiver apparatus on said chassis, with the base of said coil units being positioned in edge to edge rela tionship and together having a perimeter greater than the aperture in said chassis and overlying said aperture whereby to be supported on said chassis beyond the aperture edge, a single shield member for mounting over said pair of coil units and adapted to be secured to the chassis, securing means for said shield extending through said insulating bases at their abutting edges and actingto secure said basestosaid chassis aswell as secure said shield to said chassis, and the assembly oi the structure and connections on each base being such as to permit the assembly on and the removal from said chassis of each coil unit independent of the other coil unit.

WILLIAM L. DUNN.

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