US 2754487 A
Description (OCR text may contain errors)
July 10, 1956 R. s. CARR Em 2,754,487
T-CONNECTORS FOR COAXIAL CABLS Filed March 14, 1952 2 Sheets-Sheet 1 fzz// mmf/cm@ @0m/v6 M/ July 1o, 1956 R. s. CARR Em 2,754,487
T-CONNECTORS FOR COAXIAL CABLES Filed March 14, 1952 2 Sheets-Sheet 2 gj N @x ,SN
Unite ttes Patent T-CONNECTORS FOR COAXIAL CABLES Robert S. Carr, Summit, and Tore N. Anderson, Mountainside, N. J., assignors to Air-tron, Inc., Linden, N. J., a corporation of New Jersey Application March 14, 1952, Serial No. 276,636 2 Claims. (Cl. 339-402) This invention relates to which are T-shaped so that, when connected to a set of coaxial cable contacts in a connection plug on a panel, the conectors arms which form the top of the T will lie close to the panel, thus being neat and occupying a minimum of space in front of the panel. The invention, further, comprehends improved methods of making such T-connectors.
An important object of the invention is the provision of such a T-connector which is simple and relatively inexpensive to produce.
Another important object is the provision of such a connector having a relatively high corona level.
Another important object is the provision of such a connector having parts which may be very easily assembled.
Another important object is the provision of an improved method of making such a connector.
The foregoing and other objects are realized by the present invention; and one of numerous embodiments of T-connectors according to this invention is shown, for illustrative purposes, in the accompanying drawings in which:
Figure l is a central, axial sectional View of a T-connector according to a preferred form of this invention, shown in partial association with related jack, panel and cable parts.
Fig. 2 is a sectional view substantially on the irregular line 2 2 of Fig. l.
Fig. 3 is a fragmentary sectional view substantially on the line 3-3 of Fig. l.
Fig. 4 is an exploded View of the components of the T- connector of Figl; most of said components being shown in elevation and some of them being shown in section or with parts broken away to show details.
The illustrated T-connector, generally designated 10, if considered only as to its essentials, consists of an outer, T-shaped shell 12 of suitable conducting metal, an inner, T-shaped conductor 14 and a preferably unitary, T-shaped dielectric sleeve 16, preferably of relatively soft silicone rubber, extending between the shell and the inner conductor. Additionally, as hereinafter detailed, there are various threaded sleeves and other parts associated with the shell 12 for connecting the latter both mechanically and electrically with the outer conductor or conductors of one or more related lengths of coaxial cable and with a jack to which another length of coaxial cable is connected.
At the lower extremity of the central member of the T-connector (locations being hereinafter recited relatively to the position of the device in the several figures of the drawing), the latter is designed and arranged to be connected like a plug to a jack assembly 18, which may be fixed to a panel or instrument wall 20 having contacts facing toward the outer side of the panel or instrument wall (toward the top of the latter as shown in the drawing). The jack assembly may have a coaxial cable 22 associated therewith; the conducting portions coaxial cable connectors 2,754 le? Patented July l0,
3 HCC of the cable being mechanically and eelctrically connected to conducting portions of the jack assembly.
At one or both upper-outer extremities of the T-connector, a separate length or lengths of coaxial cable 24 may be mechanically and electrically connected to the connector. Such connections, ordinarily, would be similar at both such extremities; hence, it should suilice to show in detail and to hereinafter describe only an adjacent end of such a length of coaxial cable connected to the upper-right extremity the connector.
As illustrated in Fig. l, the jack assembly 18 is a female connection and the lower end or center arm of the T-connector is a male connection which may be plugged or unplugged quickly relatively to the jack assembly. The outer ends of the top of the T-connector are female connections to which coaxial cables may be more or less permanently connected as hereinafter described.
The jack assembly 18 comprises a cylindrical metal shell 26, which extends through a circular opening 28 in the panel or instrument wall 2t), and is formed with an outer abutment ilange 30 which engages a circular marginal portion of one `side of the panel 26 surrounding the mentioned opening therein to locate the shell 26 correctly in place in the panel; and a lock-nut 32, threaded upon an outer threaded portion 34 of the shell 26, locks the latter rmly in its desired relationship to the panel. The cable 22 is connected to jack assembly 18 similarly to the connection of cable 24 to the top of the T-connector, all as hereinafter described.
The shell 26 constitutes an outer conductor of the jack assembly 18. The inner conductor of the jack assembly may be in the form of a female contact element 36 having spring contact fingers 38 surrounded by a metal sleeve 39, which is interiorly tapered or beveled at its upper end as at 39a to aid in guiding a contact pin of the connector into place within the said lingers. The lower end of the contact element 36 is suitably soldered to the bared end of an inner conductor 40 of the cable 22. The contact element 36, together with the mentioned end portion of the inner conductor 40 of the cable 22 and an adjacent end portion of a dielectric sleeve 42 of said cable, extends coaxially within a dielectric sleeve 44 disposed within the shell 26 and held against accidental dislodgment therefrom by suitable means, as, for example, by a split snap ring 46 which seats within an internal annular groove 48 formed within the shell 26 and extends at least partially into an outer circumferential recess 50 in a locking ring 52 which encircles and is embedded in the dielectric sleeve 44.
The dielectric sleeve of the jack assembly preferably is formed of relatively soft silicone rubber, and the dielectric sleeve i2 of the cable may be of a similar material, although, in the cable, it may be advantageous to employ a somewhat harder material formed of a polyethylene composition.
The pshaped inner conductor 14 comprises an upright, conducting metal rod 54, the lower end of which is reduced to form a Contact pin 56 and the upper end of the rod Se is reduced and threaded, as at Si?, to enable it to be screwed into a body or central portion 6b of a double, female, conducting metal contact element 62, the opposite ends of which are similar and are each formed with spring contact lingers 64 for gripping therebetween a contact pin 66 suitably soldered to the end of an inner conductor 63 of a cable 24. Disposed protectively about the contact fingers 64 are cylindrical metal sleeves 7l) which are interiorly tapered at their inner ends, as at 72, to enable them to engage tightly with the central portion 60, and are similarly tapered, as at 74, at their outer ends to facilitate entry of the contact pin 66 into rm contacting association with the lingers 64.
The outer extremities -of the top part of the metal shell 12 are formed with small, inwardly extending fianges 76 to aid in holding the top part of the dielectric sleeve 16 against material endwise shifting.
The .central leg of the dielectric sleeve 16 :extends through and protrudes from the lower end of ametal supplemental sleeve 78, the upper end of which is threaded into and welded or soldered to a collar 80; and .the upper portion of said collar is shaped complementally -to the top part of the shell 12 and suitably soldered or welded to the latter to constitute the collar as an integral shell portion. The supplemental sleeve 78, of course, becomes an integral part .of the shell after being soldered `or welded as above described.
The Asupplemental sleeve 7S is formed with an external annular recess 82 near its lower end to Areceive .therewithin the Afree ends of spring fingers 64 of Ia more or less cylindrical spring S6 having an upper lfinger-bearing base portion 68 in the form of a circular band which encircles .the supplemental sleeve 7S :and seats thereon .immediately beneath an 'outer radial ilange .90 of said supplemental sleeve. The base portion or band 8S preferably is welded -.or soldered tothe supplemental sleeve, care being taken, however, that the :spring fingers 134 are left free .to flex. As may best :be understood Afrom Figs. 1 and 2, the spring fingers S4 diverge slightly outwardly from the base portion 88 toward their lower or free ends, and .said free ends are individually -bent inwardly `to seat within the recess S2.
A flanged nut 92 is provided for holding the T-connector positively lin connected or plugged-in association with the jack 1S. This nut is internally threaded, as at 94, at its lower end to enable it to be screwed upon the threaded portion 34 of the jack 18. The upper end of the nut 92 has an inwardly extending radial ange'96 which terminates inwardly in close but, nevertheless, sliding association with the outer `surfaces of the collar 8i) and of the supplemental sleeve 78. Surrounding said collar and sleeve, and within the nut 92, are disposed a plurality of alternately arranged, at metal washers 98 and bent spring washers 196. When the nut 92 is screwed down tightly upon the jack 1S, the mentioned assembly of washers .is compressed axially, thereby holding Vthe, T--connector firmly in place in the Vjack with the ContactV pin 56 of the inner conductor of said kconnector firmly engaged ,for electrical contact within the spring contact fingers 3S of the contact element 3.6 provided in the jack 18.V lIt maybe observed from AFig. -l that the inside diameter of the upper end of the jack shell 26 is slightly less than the outside diameter of the spring 86 at Vthe divergent portions .of the latters fingers; thus, when lthe lconnector is plugged into the jack, the spring fingers 84 yieldably Contact the shell 26 and maintain a positive electrical connection between the latter shell and the shell 12 .of the T-connector.
Except for the .fact that .the inner conductor 68 of cable 24 establishes connection with a female contact of the T-connector while the inner conductor dll of cable 22 establishes connection with a male contact of said vconnector, the means by which the cables 22 and 24 may be associated with ,the connector may be substantially identical and, therefore, it should be understood that the following description of Vthe manner in which cable 24 is connected to .the toppart of :the 'T7-connector should serve also as a description of the manner in which the cable 22 is connected Vto the. jack 18.
Means for mechanically and -electrically connecting the cable 24 to an upper extremity `of the T-connector vmay comprise an annular, metal conducting sleeve 162, within an outer annular rabbet 104 of which is disposed, and' preferably soldered, a trimmed end of an outer conductor 166 of the cable 24, which conductor 'is usually in the form of a braid of Vseveral plies of conducting metal'wire.
A first clamping ferrule 108 is threaded into one end of a cylindrical clamping sleeve 110, the other end of which is threaded upon an adjacent outer end portion of the 513911.12.; this arrangement serving as a means for drawing the inner end of the ferrule 10S against an outer marginal portion of the rabbet 164- to force the inner, preferably conical or spherical, end of the conducting sleeve 102 into firm seating and electrical contacting engagement with the radial end flange 76 formed on the adjacent end of the shell 12.
The fermle 1118 toward `its outer end is for-med ywith an inner annular rabbet 112 forming an acute recess which receives therewithin a tapered inner end of a relatively soft rubber clamping ring 114. A second clamping yferrule 116 is formed with a cylindrical portion 118 which may be threaded upon the outer end of the ferrule 108, and with an inwardly extending end flange 12) which abuts the outer end of a washer 122 which is disposed between the flange 120 and the adjacent outer end of the rubber clamping ring 114.
When the ferrule 116 is threaded tightly upon the ferrule 108, the ywasher 122 is forced axially inwardly so that its tapered end 124 engages the adjacent complementally tapered end of the rubber clamping ring 1141. T'hus, :the ring 114 is squeezed between the acute or angular wall `of the rabbet 112 and the tapered inner end of the washer 122, thereby causinU the clampingring to become deformed radially inwardly into a very firm clamping engagement with an adjacent portion of an outer insulating jacket 126 ofl the cable 24. lt will be seen that, by the several ferrules and other parts-just described, the cable is held firmly against unintended dislodgment from its connected relationship with the upper part of the T-connector. With the parts thus held together, the outer conductor 166 of the cable is held in firm conducting connection, through conducting sleeve 102, with the shell 12 which constitutes the outer conductor of the T-connector, while the inner conductor 63 of the cable is maintained in firm conducting connection, through contact pin 66, with the inner conductor 14 of the T-connector.
iin-connecting the end of the cable 24 to the T-connector, the second clamping ferrule 116, the washer 122, the rubber clamping ring 114 and the first clampingA ferruleflibS yare slid onto the free end of said cable approximately in their relationships shown in Fig. l. Then, at the free end of the cable, the latters insulating jacket 126 :and its outer conductor 106 are stripped back to some extent to expose the dielectric sleeve 128 of the cable; then the vlatter vis stripped away forA a short distance to enable the inner conductor 68 of said cable to be inserted in and soldered to the contact pin 66. The cutting back of the 4outer conductor 166 and of the insulating jacket 126 :should be approximately to the extent indicated in Fig. l in order to leave a substantial, exposed endY portion ofthe-dielectric sleeve 12S to telescope withinjthre endof the top-part of the T-shaped dielectric sleeve of the connector.
Preferably after the contact ,pin 66 has been soldered to the end of the inner conductor 68, the metal conducting `sleeve '102 is slid vonto and along the dielectric sleeve 128, and its small-'diameter end is forced between the last-mentioned dielectric sleeve and the outermost end ofthe outer conductor 166 of the cable to such anextent that the-fend of said outer conductor seats within the rabbet '11M-:in -the conducting sleeve.
The outer conductor preferably is soldered in place about and upon the sleeve 12; Then the contactv pin 66=ancl the `adjacent end portion ofthe inner conductor 68 of the cable land the surrounding exposed portion of the dielectric sleeve '12,8 ofthe cable are pressed forcibly into the adjacent end portion of the upper outer extremity of the T-shaped dielectric sleeve` 16 of the connector until the Contact pin 66 enters between and is Vfirmly gripped in electrical contact by theiingers V64. A suitable lubricant such as silicone grease may be applied to,..said.;ex;
posed portionof the dielectric sleeve 12.8 to facilitate ther armas? introduction of the latter into the dielectric sleeve 16 and to provide a tight, voidless t therebetween.
Assuming that the stripping of the cable has been done to the proper extent, the large end of the conducting sleeve 102 then will be in firm contact with the metal shell 12 at the latters radial flange 76. With the parts in the relationship just mentioned, the ferrules 108 and 116 may be drawn up tightly to hold the cable firmly in its connected relationship with the shell 12 and to expand the soft rubber clamping ring 114 radially to cause it to firmly grip the insulating jacket 126 of the cable 24.
We have shown in our copending applications Serial No. 199,944, tiled December 9, 1950, now Patent No. 2,698,353, dated December 28, 1954, relating to electric cables, and Serial No. 257,276, filed November 20, 1951, now abandoned, relating to elbow connectors for coaxial cables, that a high-corona voltage level may be imparted to and maintained in a cable and in connectors for cables by coating the inner surface of a dielectric sleeve, which immediately surrounds a metal conducting core, with a thin, fluid, conducting compound, thereby assuring a substantially continuous and extensive electrical contact between said core and sleeve. Both of said copending applications also show that the maintenance of a high-corona voltage level in cables and connectors is aided, where the cables are srs-called coaxial cables and where the connectors are designed for connecting such coaxial cables, by similarly applying the thin, fluid, conducting compound to the outer surface of such a dielectric sleeve where the latter is in face-to-face relationship with a surrounding outer conductor of a coaxial cable or a surrounding shell portion of a connector which functions as an outer conductor. The principle, as disclosed in the mentioned copendin g applications, may be employed advantageously in T-connectors such as herein disclosed. Although a variety of conducting fluid compounds may be utilized in this relation, nevertheless, a conducting lluid compound that has served satisfactorily as a means of maintaining a high-corona level in the connection is one which is made by mixing powdered graphite and silicone, to which is added sufficient toluol to reduce the mixture to a very thin liquid approximately of the consistency of water.
The silicone referred to is a recently developed cornposi tion comprising silica, reacted by molecular rearrangerent to render it dispersible in solvent. It is in the nature of a relatively non-electric-conductive silicon varnish which was developed primarily as an insulating medium that could be applied in fluid form to parts to be insulated. Several purposes of the silicone in the present invention are to serve as a medium for holding the graphite in suspension in the toluol, also as a more or less fluid vehicle for the graphite upon complete or partial evaporation of the toluol, and as a means of controlling the concentration of graphite whereby to control the conductive characteristics of the fluid, conducting coating.
lt has been found that satisfactory results are derived in practicing this invention where approximately equal parts by weight of silicone and graphite are used. As substances other than silicone and powdered graphite may be employed in the stated manner and for the stated purposes, reference is sometimes hereinafter made to a fluid suspension vehicle as referring broadly to any fluid medium which functions for the stated purposes in association with graphite or an equivalent conductive powdery substance, and the term conductive powdery substance is employed herein as referring broadly to any powdery substance which functions for the stated purposes in association with a fluid suspension vehicle.
As it would be practically impossible, because of the thinness of such fluid composition coating, to show it satisfactorily in the drawings, it is considered desirable to state that such a fluid compound would form a substantially continuous coating within the several dielectric sleeves of the T-conriector and of the cables connected therewith. The fluid composition on such inner, dielectric sleeve surfaces, as considered from the right end of Fig. 1, would maintain contact and substantially fill any spaces between said inner sleeve surfaces and the outer surfaces of the inner conductor 63 of cable 24, the contact pin 66, the cylindrical metal sleeve 7f3, the upright rod 54, the metal sleeve 39, the female contacting element 36 and the inner conductor di; of the cable 22. The liuid composition, of course, is similarly located in the upper left arm of the T-connector and the cable which is connected to said arm.
Again proceeding from the upper right end of Fig. l, the lluid, conducting composition applied to the outer surfaces of the several dielectric sleeves would also be contact with the inner surfaces of the outer conductor of the cable 24, conducting sleeve lllZ (as well as the outer end surface of said sleeve), the top or main portion of the metal shell 12, the collar du, the supplemental metal sleeve 7S, the cylindrical shell 26 of the jack assembly and the conducting sleeve and outer cable conductor which, in relation to the jack assembly, correspond to the parts .lttZ and 1&6 just enumerated.
The manufacture of T-connectors of the character disclosed in this application obviously presents some dilliculties. These diiliculties, however, have been overcome by methods substantially as will now be described.
The principal difficulties arise in relation to the disposition of the Tshaped dielectric sleeve 16 within the T-shaped metal shell 12 and in the disposition of the T-shaped inner conductor 14 within the said dielectric sleeve. According to the present invention, ythe Icollar 8l? is first welded to the top part of the metal shell 12 in which, of course, has previously been cut an opening to coincide with said collar, so that said top part of the shell opens directly into the collar and other parts associated therewith.
After the collar Sil has been welded to the top part of the metal shell, the thus-integrated parts are placed within a mold, which, with the said integrated parts, will define a cavity of the same size and shape as the dielectric sleeve 16 to `be formed. Suitable core elements, of course, are associated with .the mold to provide the central T-shaped passage in the dielectric sleeve. The dielectric sleeve 16 is then molded in place.
After removal of the partial shell and dielectric sleeve 16 from the mold, a thin coating of the hereinbefore described lluid, conducting composition is applied to certain surfaces of said dielectric sleeve. The said conductl, ing compound may be introduced between said sleeve and surrounding interior surfaces of the shell `by being injected between the sleeve and shell by a pressure needle such as a hypodermic needle or its equivalent; lthe needle being properly directed through the opposite open ends of the metal shell and/or at the bottom of the collar 80. It has been found, however, that the said fluid, conducting compound may be advantageously pumped into place Vbetween the shell and the dielectric sleeve by using a pressure fluid pump or gun fitted with an annular adapter which can be attached to one end of the top part of the metal `shell 12. Fluid, conducting compound thus directed between the `dielectric sleeve and 'the shell, toward one end thereof, moves under pressure entirely to the opposite end of the shell and to the bottom edge of `the collar Sil. Said compound may then be applied in any suitable manner, as by brushing, to the end faces of the dielectric sleeve 16 at its opposite top ends and to the exterior of the upright part of said sleeve; avoiding, however, the application vof the said compound to the bottom end face 16a of said sleeve.
After the outer surfaces of the dielectric sleeve are coated, as just described, separate, similar, round man drels or plugs are pressed into opposite ends of the cavity then existing in the top part of the dielectric sleeve. These mandrels or plugs are extended into the dielectric sleeve to -thesame kextent @as thedielectric sleeves ofrelated cables V24 will extend in a Afully .assembled-connec tor and related cables. With :the ends of 'the top -part of the sleeve 16 thus plugged, itmay then be inverted and some of the mentioned uid, conducting compound poured into the cavity in said sleeve, after which the excess conducting compound material is poured out. Any of said compound which becomes deposited upon the llower end 16a of the said dielectric sleeve is then wiped or otherwise cle-aned away as it is desired that there be a good dielectric engagement between said end surface and the opposed end face 44a of the dielectric sleeve of the jack assembly 18. By making 'the surface 16a convex -as best shown in Fig. l, it presses iirrnly and completely upon lthe surface '44a when the two mentioned sleeve portions are pressed together by tightening of the nut 92.
After excess conducting compound has been poured out as just described, the shell and dielectric sleeve assembly is heat-treated as by baking to set the said compound, which 'thereby becomes more or less ltacky. To bring about this condition where the said .compound is of the character hereinbefore described, the baking may be conducted at about 150 centigrade for from six to ten hours or overnight. After such -heat treatment, the mandrels or plugs are removed.
After removal of the mandrels .or plugs, the double female contact element 62 is pushed into its proper position from one top vend of the dielectric sleeve 1.6, after which the upright rod 54 is inserted from the bottom end of said sleeve and threaded into the contact element 62. The cylindrical metal sleeves '7.9 may then be pushed into place from opposite top ends of said dielectric sleeve. If desired, the sleeves 70 may be properly assembled with the contact element 62 before-the latter is pushed into said dielectric sleeve and the said sleeves and Contact element may be simultaneously pushed into place as a unitary assembly.
Preferably before the rod 54 is inserted, the supplemental metal sleeve with the spring 86, washers 98 and 100, and vthe flanged nut 92 properly associated therewith as shown in Fig. 1, may be threaded into the collar 80 and welded thereto or otherwise held against becoming unthreaded therefrom.
The-completion; of an assembly of the T-connector with the jack assembly 1,8 and -with cables 24 has already beenjfullydescribed.
It should be -apparentfrom `the foregoing that av T-connector as herein disclosed fulfills all the stated objects of this invention; and, lfurthermore, that the inventive concept may be embodiedin various vstructures other than the single illustratedv embodiment without, however, dcparting from the invention as defined in the following claims.
1. A T-connector for coaxial cables comprising a rigid, T-shap-ed, electrically conductive, metal, outer shell, a T-shaped dielectricsleeve of pliant insulating material, a T-shaped inner conductor member having T-constituting portions with outside diameters slightly greater than the lnormal inside diameters of adjacent sleeve portions, the pliancy of the sleeve material being such as to permit `said T-consti'tuting portions of the inner conductor member to 'be inserted endwise into said sleeve inV intimate association therewith, and a semidiuid, conductive coating between and in contact with said slee-ve land inner conductor member; said conductive coating consisting essentially of sil-icone varnish, powdered graphite and toluol.
2. A T-connector according to claim 1, further including, between and in contact with said dielectric sleeve and said outer shell, a semi-uid, conductive coating lconsisting essentially of silicone varnish, powdered graphite and toluol.
References Cited in the le of this patent UNITED STATES PATENTS Re.21,926 Bormann- Oct. 2l, 1941 2,335,041 Bruno Nov. 23, 1943 2,379,942 Webber ,J'uly 10, 1945 2,389,705 Wetzel Nov. 27, 1945 2,399,314 Barker et al Apr. 30, 1946 2,422,982 Quackenbush June 24, 1947 2,457,796 White Dec. 28, 1948 2,473,570 Chirelstein June 21, 1949 2,642,474 Bowar June 16, 1953