[191
`United States Patent
`
`McMills et al.
`[45] Date of Patent:
`Nov. 8, 1994
`
`[11] Patent Number:
`
`5,362,250
`
`l|||||l|||l|||||||||||||l|||||||lllll||l||||||l||||||l||l||||l|I|||||l|||||
`USO0S362250A
`
`[54] COAXIAL CABLE CONNECTION IVIETHOD
`AND DEVICE USING OXIDE INHIBITING
`SEALANT
`Inventors: Corey Mcl\¢1i.|ls, Los Altos; John
`Sunnyvale, both of
`
`_
`[73] Assignee: Raychem Corp-oration, Menlo Park,
`Calif,
`
`{'35}
`
`1/1933 T0}! -
`4-721-332
`4355-152 7/1933 E1310‘ 9‘ 31-
`-
`1%: get; ......................................
`,
`,
`c en:na.n
`
`4.834.675 5/I989 Samishisen
`4,364,725 9/I939 Dehbaut .
`5.066.243 I1/I991 Gavel‘ etal. ...................... .. 439/573
`
`439/573
`
`FOREIGN PATENT DOCUMENTS
`
`1211 W
`_
`[22] Filed:
`Nov. 25, 1992
`[51]
`Int. Cl.5 ............................................... H0111 4/24
`I.-LS. (:1. .................................. ..
`439/935
`_
`[58] Field of Search .............. .. 439/337, 333, swsss,
`439/936
`
`[561
`
`°2°::::;;: 12:13:: sum l
`ermauy .
`521459 4/1949 United Kingdom .
`ml342GA 8/1979 Umted Kmgdom '
`‘Prfn-igus Exgmfnerfljoseph H‘
`Attorney, Agent, or F:'rm—Herbett G. Burkard; A.
`Stephen za\,e11
`5
`
`IRA
`
`Cr
`ABS
`References Cited
`rovided which allows the
`de ice is
`d
`thod
`p
`v
`an a
`e
`US‘ PATENT DOCUMENTS
`connection of coaxial cable termini to one another with
`2,199,532 5/ 1940 Weeeks ............................. .. 439/387
`minimum 1ong.term loss of RFI shielding The method
`$1} 2 comprises the removal of metal oxides from the concen-
`7/1965 Mo::i1o.ri:'.m.T.
`1‘. 339/111
`Vic °°”d“°‘°’ P‘:;fi°“s °ffl"e.“"° °ab1° ‘°’mi”i’.a?ply'
`3:196:38:
`3,26-1,602 8/1966 Schwartz
`339/177
`‘"3 5 5°“1“’“_‘°
`‘°- °°“°°‘““° °°“d“°‘°’ "°_"P'“1 and
`3,353,254 12/1957 Brejcha’ J,_ _
`then connecting the central conductor termini to one
`3,492,408
`l/19'.-'0 Foi-ney.Jr.eta1.
`another and the concentric conductor termini to one
`3,550,064 12/ 1970 Caller. 61 al.
`-
`another. The device comprises a cone: structure dimen-
`ufi :1”-’i"3'h ---------------------------" 33911’;
`sioned to slip over the outside of a standard connection
`s/1973 T233: et“§1'.”:T.
`.'.'.: 29/629
`jack‘ Within the “net 5”'"°“"° i';‘fi5P°f"’d 3 qmnmy
`33311313
`3,731,762 12,1973 Qumkenbush _
`339/89 C
`of sealant and the collet structure as at east one aper-
`3,953,321
`5/1975 Bulge, at 31
`_ 339/177 5
`ture through which sealant oozes from the collet struc-
`4,053,200 10/19?‘? Pugner ......... ..
`. 339/ 11"! R
`ture to the exterior of the collet structure. When the
`4,173,335 11/1979 Fenn ct 31» «
`- 339/177 13
`collet structure is attached to the jack, the sealant is
`4,249,790
`2/1981 Ito et al. ........................ .. 339/177 E
`caused to ooze Onto the concentric conductor thereby
`i:§‘§‘;i:§ii
`3151332
`§i‘Lit'fi’1;“‘.T:..:.................... 339/17? R
`Sealing the °°n==n“i° °°nd“°*°r M ‘be ambient-
`4,60(},261
`7/1986 Debt:-ant
`.
`4,634,207
`1/I987 Debbaut .
`
`13 Claims, 3 Drawing Sheets
`
`
`
`.
`
`52
`
`
`
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`
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`
`
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`CORNING EXHIBIT 1036
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`

`
`U.S. Patent
`
`Nov. 8, 1994
`
`Sheet 2 of 3
`
`5,362,250
`
`

`
`US. Patent
`
`Nov. 8, 1994
`
`Sheet 3 of 3
`
`5,362,250
`
`
`
`FIG. 58
`
`FIG. 5b
`
`

`
`1
`
`5,362,250
`
`COAXIAL CABLE CONNECTION METHOD AND
`DEVICE USING OXIDE IN]-IIIBITING SEALANT
`
`U.S. PATENT APPLICATIONS INCORPORATED
`BY REFERENCE
`
`This application incorporates herein completely the
`entirety of U.S. patent application Ser. No. 07/912,106,
`filed Jul. 9, 1992, U.S. patent application Ser. No.
`07/509,669, filed Apr. 19, 1990, U.S. patent application
`Ser. No. 07/434,068, filed Nov. 8, 1989, and U.S. patent
`application Ser. No. 07/364,917, filed Jun. 9, 1989.
`FIELD OF THE INVENTION
`
`This invention relates generally to methods and de-
`vices for connecting the termini of coaxial cables to-
`gether and, specifically,
`to methods and devices for
`sealably connecting the termini of coaxial cables while
`minimizing radio frequency interference.
`BACKGROUND OF THE INVENTION
`
`Coaxial cable is widely used for distributing wide
`band radio frequency information, such as television
`and radio signals. The cable television/radio industry,
`which relies almost exclusively on coaxial cable, is one
`of the most rapidly expanding segments of the United
`States’ economy. It is anticipated that in the very near
`future the amount and type of information available via
`coaxial cable networks will be greatly expanded beyond
`traditional television and radio signals. Coaxial cable
`networks may soon be the principal vehicle by which
`consumers obtain their daily news, access library infor-
`mation, do their shopping, pay their bills, and otherwise
`interact with much of the outside world. Maintaining
`and controlling the integrity of these critical coaxial
`cable distribution networks is a major challenge for the
`cable network industry.
`Coaxial cable typically includes a central axial con-
`ductor and an outer conductor which is disposed con-
`centrically around the central conductor. A low-loss,
`high dielectric insulation material, such as plastic foam,
`separates the two conductors. An outer
`insulating
`jacket is often provided over the concentric conductor
`to provide electrical insulation, shielding and physical
`protection to the cable. The concentric conductor may
`be a single continuous element or, more commonly, it is
`a composite of several layered elements of thin conduc-
`tive foil, wire braid or similar material. The foil, braid or
`other similar material is generally made from an alumi-
`num alloy.
`Coaxial cable networks comprise lengths of cable
`connected to one another by connection equipment.
`Such connection equipment most often takes the form
`of a male/female connection system wherein the male
`member includes a connection jack and the female
`member includes a threaded or friction-fit coupler di-
`meusioned to couple with the male jack. As shown in
`FIG. 1, a standard connection jack RG-59 cable, com-
`prises a cylindrical, externally threaded body. For
`RG-59 cable the outside diameter of the jack is about
`0.375 inches (0.952 cm). The outwardly projecting end
`of the jack is covered by a planar member which has a
`central aperture. Behind the aperture, within the con-
`fines of the body of the jack, is disposed an internal
`conductor. The body is electrically connected to one of
`the coaxial cable circuits and the inner conductor is
`connected to the other coaxial cable circuit.
`
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`2
`The female member in the typical male/female con-
`nection system commonly comprises a jack connection
`moiety which is adapted to attach to the cable connec-
`tion jack. The female member also comprises a cable
`connection moiety which physically attaches to the
`terminus of a coaxial cable in such a way that the cable
`connection moiety is in electrical contact with the con-
`centric conductor of the coaxial cable. The cable con-
`nection moiety is adapted to allow the terminus of the
`central conductor to project through the center of the
`female member without contacting the female member,
`so that, when the jack moiety is attached to the outside
`of the conductor jack body, the central conductor ter-
`minus protrudes into the connection jack central aper-
`ture (without contacting the jack connection moiety of
`the female member or the conductor jack body) and is
`placed into electrical contact with the internal conduc-
`tor of the connection jack. It is a basic requirement of
`the male/‘female connection system that electrical conti-
`nuity is provided between the outer concentric conduc-
`tors and the central conductors of joined cables while
`maintaining isolation between these conductors.
`When all of the connections along a run of coaxial
`cable are properly made, the cable is largely shielded
`from the receipt and emission of electromagnetic radia-
`tion. This is because the outer concentric conductor
`carries a current which is precisely the reverse of that
`which is carried by the central axial conductor, so that
`the resulting pair of magnetic fields cancel each other
`out. If, however, the concentric conductor is improp-
`erly connected anywhere along the cable run, little or
`no reverse current will flow along that conductor and
`the shielding normally present in the cable run will be
`eliminated. Without such shielding, the signal current
`traveling along the central axial conductor will emit
`electromagnetic radiation to the atmosphere, and extra-
`neous electromagnetic radiation from the atmosphere
`will be received by the central axial conductor.
`Electromagnetic radiation in the radio frequency
`range can present at least two problems. Firstly, incom-
`ing radio frequency radiation interferes with the signal
`carried by the central axial conductor. Secondly, radio
`frequency radiation emanating from the central axial
`conductor interferes with other radio wave receiving
`equipment in the vicinity. The Federal Communications
`Commission (FCC) has promulgated and enforces strict
`regulations regarding radio frequency emission interfer-
`ence (“R.FI").
`Improper connections along concentric conductor
`circuits can arise for several reasons. Firstly, the con-
`nection equipment is sometimes improperly installed or
`a subsequent event may mechanically damage the con-
`nection equipment. Secondly, the connection termini
`are frequtly covered by a coating of oxidation at the
`time of initial connection. Finally, the connection ter-
`mini tend to continue to oxidize after installation. This
`phenomenon is especially prevalent where the concen-
`tric oonductor is made from an aluminum alloy.
`The prior art contains numerous methods and devices
`to provide long-term integrity of the outer conductor
`circuit. For example, methods and devices which use
`mechanical techniques for creating an especially strong
`contact between connection elements and the outer
`conductor have been tried. However, these methods
`and devices are generally expensive and usually require
`the use of special tools. Also, the methods are of limited
`value in protecting the connection points from the ef-
`
`

`
`5,362,250
`
`3
`fects of long-term oxidation of the conductor termini by
`the atmosphere.
`Other attempts calculated to provide the long-term
`connection integrity have used mechanical sealing
`means to seal off the connection points from the atmo-
`sphere. However, these methods usually entailed expen-
`sive and complex connection equipment. Also, such
`mechanical sealing means offer only limited value
`against the long-term diffusion of oxidizing elements
`into the connection area.
`Finally, several attempts have been made to seal co-
`axial cable connections using a sealant grease or gel.
`However, these attempts have been found to be less
`than fully satisfactory, presumably because these at-
`tempts do not address the problem of initially existing
`oxides on the connection termini.
`Therefore, there is a need for a simple and inexpen-
`sive method and device for connecting the coaxial cable
`termini in such a way that RFI shielding problems are
`minimized.
`
`SUMMARY
`
`5
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`
`The invention satisfies this need as well as many other
`benefits obvious to the skilled artisan.
`The invention is a method for connecting the termini
`of two or more coaxial cables wherein the coaxial ca-
`bles have a central axial conductor and at least one
`outer concentric conductor. The method comprises the
`steps of: coating the concentric conductors with an
`oxide abrading sealant, connecting the central axial
`connectors, and connecting the concentric conductors.
`The oxide abrading sealant
`is sufficient abrasive to
`abrade away metal oxides from the concentric conduc-
`tor termini during the connection step but is not so
`abrasive so as to damage the thin foil and/or wire braid
`at the cable terminus.
`Preferably the sealant is resistant to oxidation and is
`insoluble in water. It is also preferable that the sealant
`has sufficient viscosity to keep it from flowing away
`from the concentric conductor connection under any
`anticipated operating conditions.
`The invention is also a coupling device for oxida-
`tively sealing a coaxial cable to a cable port or cable
`splice. The coupling device comprises a cable connec-
`tor having at least one connection end which contains a
`sealing amount of an oxide abrading sealant.
`In a preferred embodiment, the coupling device is
`adapted to connect a coaxial cable terminus to a stan-
`dard coaxial cable connection jack, wherein the con-
`nection jack comprises a body with a connection jack
`aperture and an internal electric conductor insulatingly
`disposed within the body proximate to the connection
`jack aperture. The device comprises:
`a. an electrically conductive connection jack attach-
`ment moiety comprising a connection jack attach-
`ment moiety and a cable attachment moiety,
`the connection jack attachment moiety defining a
`collet structure having a base, a base aperture, at
`least one grease aperture and a plurality of flared
`fingers, and
`the cable attachment moiety having an open ended
`hollow cylinder which communicates with the
`collet base aperture,
`wherein the connection jack attachment moiety is
`dimensioned to attach snugly around the body of 65
`the connection jack and the cable attachment
`moiety is dimensioned to electrically and shield-
`ingly attach to the cable attachment moiety
`
`35
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`4
`while with the concentric conductor axially
`through the collet base aperture, through the
`connection jack aperture, and into electrical
`contact with the internal electrical conductor;
`b. a hollow, open-ended swagging shell disposed
`around the connection jack attachment moiety and
`comprising a compression moiety and a retraction
`moiety, the compression moiety being dimensioned
`to tightly surround the flared fingers of the connec-
`tion jack connector so as to apply hoop stress
`thereto and so as to urge the flared fingers into
`tight connection with the body of a connection
`jack attached to the terminus of the cable;
`c. a sealing quantity of sealant disposed within the
`collet structure; preferably the quantity of sealant
`being sufficient to fill at least about 4-0 percent of
`the volume defined by the colic! structure; and
`d. removable cover means for cooperating with the
`collet structure to substantially encapsulate the
`quantity of sealant.
`Preferably each of the flared fingers in the comiection
`jack connection moiety has a sealant aperture. It is also
`preferable that the slits between the flared fingers be
`covered by a thin, flexible webbing.
`In one embodiment, the removable cover means com-
`prises a cap having an end cover and a cylindrical body.
`Preferably the cylindrical body has sufficient length to
`seal the slits between the flared fingers of the collet
`structure. Also preferably,
`the removable cover is
`adapted to interlock with the collet structure in such a
`way that the cap cannot be rotated about the cable
`terminus independent of the collet structure. This pre-
`ferred embodiment of the cap allows the cap to be used
`as a “wrench” to make it easy for a user to install the
`connection jack attachment moiety to the cable termi-
`nus.
`
`The invention provides for the first time a simple and
`inexpensive method for ensuring RFI shielding of a
`coaxial cable run. even after years of use in outdoor
`service. The method of the invention is easy to apply
`and the device of the invention is inexpensive and sim-
`ple and easy to use. An additional benefit of the inven-
`tion permits retrofitting onto existing coaxial cable runs
`without special tools or equipment.
`DESCRIPTION OF 'I'I-[E DRAWINGS
`
`These and other features, aspects and advantages of
`the present
`invention will become understood with
`reference to the following description, appended claims
`and accompanying illustrative drawings, where:
`FIG. 1 is a cross-sectional view of a coaxial cable
`connection system having features of the invention;
`FIG. 2 is a prospective view of a connection jack
`connector having features of the invention;
`FIG. 3 is a prospective view of an assemblage having
`features of the invention;
`FIG. 4 is a cross-sectional view of a second connec-
`tive jack connector having features of the invention;
`FIG. 5a is an end view of a connection jack connec-
`tor having web between the flared fingers; and
`FIG. 5b is an end view of a connection jack connec-
`tor having an external sleeve to create a web between
`the flared fingers.
`
`DESCRIPTION
`
`The invention is a method for connecting the termini
`of two or more coaxial cables wherein the coaxial ca-
`bles each have a central axial conductor and an outer
`
`

`
`5,362,250
`
`5
`concentric conductor. The method comprises the steps
`of coating each of the concentric conductors with a
`sealing amount of an oxide abrading sealant, connecting
`the central conductors to one another, and connecting
`the conctric conductors to one another. Optionally,
`before the central conductors are connected to one
`another, they are also coated with the sealant.
`The sealant is sufficiently abrasive to remove oxides
`from the concentric and central conductors. However,
`the sealant is not so abrasive so as to substantially dam-
`age the thin foil and/or wire braid in the concentric
`conductor.
`
`The sealant base material can be prepared from a
`wide variety of organic and inorganic oils, greases and
`waxes. A suitable sealant is a vegetable oil based grease
`distributed by Blackburn, Division of FL Industries,
`Inc. of St. Louis, Mo. under the name “8-3 Contax.”
`Another material which has been found suitable as a
`sealant is a mixture of about 20% oil and about 80%
`wax.
`An abrasive material is added to the sealant base
`material. In one embodiment, glass beads having a di-
`ameter range between about 0.0191 inches (0.0000254
`cm) and about 0.002 inches (0.00508 cm) are added into
`the sealant. Preferably the diameters of the glass beads
`are between about 0.0003 inches (0.{.‘lIJ762 cm) and
`about 0.0008 inches (0.002032 cm) in diameter. Other
`dielectric materials besides glass may also be used, such
`as sand or silica. Also, the abrasive material need not be
`spherical. For example, glass fibers could be used as the
`abrasive material.
`The sealant is preferably chemically resistent to ele-
`ments preaent in the ambient environment. The sealant
`should be resistant to oxygen penetration. The sealant
`should also be resistant to air pollutants and to organic
`degradants. The sealant is also preferably insoluble in
`water and in all other liquids which may contact con-
`centric conductor connection.
`It is important that the sealant be sufficiently viscous
`to prevent slumping and flowing under service condi-
`tions. Preferably the viscosity of the sealant at about 68°
`Fahrenheit (20° Celsius) is at least about 1,000 cps. At
`about 150° Fahrenheit 056“ Celsius) is also preferable
`that the viscosity of the sealant be at least about 500 cps.
`The sealant should not, however, be so viscous so that
`it cannot be easily displaced during the connection
`procedure or at low temperatures. Ideally, the viscosity
`of the sealant at about 68° (20” Celsius) Fahrenheit is
`between about 2,0(Il cps and about 50,C0.'J cps, and at
`about 150” Fahrenheit (66° Celsius), between about 500
`cps and about l,C00 cps.
`As shown in the drawings, the invention is also a
`coupling device 8 useful in the connection of a coaxial
`cable terminus 32 to a standard coaxial cable connection
`jack 38 using the method of the invention. As used
`herein, the phrase "standard connection jack” refers to
`that most common connection jack having (1) a body 4-6
`with a connection jack aperture 76 and (2) an internal
`electrical conductor disposed within, but insulated from
`the connection jack body proximate to the connection
`jack aperture 76.
`The coupling device 8 comprises a connection jack
`connector 10, a hollow swagging shell 12, a quantity of
`sealant 78 and removable cover means to substantially
`' encapsulate the quantity of sealant 78.
`The connection jack connector 10 comprises two
`connection ends, a connection jack attachment moiety
`16 and a cable attachment moiety 18. The connection
`
`6
`jack attachment moiety 16 has a collet structure with a
`collet base 20 and a plurality of flared fingers 22 which
`extend outwardly from the base 20 to form a collet
`attachment cup 24 having a peripheral edge 26.
`The collet base 2|] defines a central aperture 28 di-
`mensioned to allow the central conductor 30 of a coax-
`
`ial cable terminus 32 to protrude through the collet base
`20 into the collet cup 24 without making electrical
`contact with the connection jack connector structure.
`A typical circular central aperture 28 has a diameter
`between about 0.15 and about 0.30 inches.
`
`The fingers 22 define the collet cup 24 and provide an
`inside cylindrical engagement surface 34 suitable for
`engaging the outer threaded surface 36 of a connection
`jack 38. The inside surface 34 of the fingers 22 may be
`smooth or it may be provided with a shallow—cut helical
`groove, thread or ridge 40. Preferably, each finger can
`have a ridge 40 running laterally across the width of
`each finger 22. The pitch of the ridge 40 is set to corre-
`spond with the thread pitch of the jack 38. In embodi-
`ments having the ridge 40, a more positive attachment
`can be achieved between the connection jack connector
`10 and the connection jack 38.
`Preferably, each finger 22 is formed with a thickened
`region 44 adjacent to the chamfer 42 and becomes grad-
`ually thinned toward its connection with the collet base
`20. The inside geometry of the collet cup 24 is generally
`cylindrical when in an unstressed, uncompressed state.
`When in such unstressed, uncompressed state, the coilet
`cup 24 defines a slightly curved or frustroconical geom-
`etry. This allows the connection jack attachment moi-
`ety 16 to be easily slipped over the outside surface 36 of
`the connection jack body 46.
`The collet cup 24 is dimensioned so that, in its un-
`stressed state, it can be easily slipped over the outer
`surface of a connection jack body 46 but, when hoop
`stress is applied to the external surface of the fingers 22,
`the connection jack attachment moiety 16 can be tightly
`connected around the body 46 of a connection jack 33.
`In a preferred embodiment to be used with a jack
`having an outside diameter of 0.375 inches (0.952 cm),
`the collet structure comprises four fingers 22, each dc»
`fining a quadrant of a cylinder having an inside diameter
`between about 0.37 inches (0.940 cm) and about 0.38
`inches (0.965 cm). Each finger is between about 0.2
`inches (0.503 cm) and about 0.5 inches (1.270 cm) long.
`Each finger 22 is separated from an adjacent finger by a
`longitudinal slit 48 which can be between about 0.01
`inches (0.0254 cm) and about 0.1 inches (0.254 cm)
`wide, preferably between about 0.04 inches (0.101 cm)
`and about 0.05 inches (0.270 cm) wide. The fingers 22
`may he formed by cross-sawing across the collet struc-
`ture at right angles. Alternatively, and preferably for
`mass production, the fingers 22 are formed by a single
`machining operation of two parallel saws which move
`in one direction across the collet structure.
`In a most preferred embodiment. the longitudinal slits
`48 between the fingers 22 is covered or filled with a thin
`flexible web 49. The web 49 is sufficiently flexible so as
`to be readily deformed when hoop stress is applied to
`the collet structure. The web 49 can be any suitable
`material having sufficient flexibility. The web 49 can be
`a thin sleeve 51 disposed over the collet structure as
`shown in FIG. 5b. For efiiciency of manufacture, the
`web 49 is integral with the finger 48 as shown in FIG.
`5a. It has been found that the use of a web 49 improves
`the distribution and abrasive action of the sealant during
`
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`5,362,250
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`7
`installation by not allowing the sealant to be extruded
`out through the slits 48.
`The connection jack connector 10 further comprises
`a cable attachment moiety 18. The cable attachment
`moiety 18 is physically attached to the connection jack
`attachment moiety 10 proximate to the collet base 20.
`The cable attachment moiety 18 is also adapted to at-
`tach to the coaxial cable terminus 32 in such a way that
`the cable attachment moiety 18 is in electrical contact
`with the concentric conductor 50 of the cable terminus
`32 while the central conductor 30 is caused to protrude
`axially through the collet base aperture 28 and into the
`center of the collet cup 24.
`The cable attachment moiety 18 can be any of the
`standard crimp-on varieties commonly known in the
`industry. The cable attachment moiety 18 can also be
`one of the several types disclosed in U.S. patent applica-
`tion Scr. No. 07/364,917, which is completely incorpo-
`rated herein by reference for all purposes.
`Preferably, however, the cable attachment moiety 18
`is a screw mandrel 52 having (1) a cylindrical mandrel
`element 54 and, (2) a helical knife-blade ridge 56 which
`forms a screw thread defined on the exterior of the
`mandrel element 54. The mandrel element 54 is gener-
`ally cylindrical having an outside diameter chosen for
`use with the size of the cable outside diameter with
`which it is to be used. For RG-59 cable, the preferred ‘
`outside diameter of the mandrel element 54 is between
`about 0.20 and about 0.21 inches. Preferably, the man-
`drel element 54 is slightly frustroconical for ease of
`insertion. Also, in a typical embodiment, the portion of
`the mandrel element 54 distal from the collet base 20 is
`thinned to provide a sharp rearward opening 58. The
`helical knife-blade ridge 56 has a height which is be-
`tween about 0.02 inches (0.0508 cm) and about 0.06
`inches (0.152 cm), preferably between 0.038 inches
`(0.0965 cm) and 0.042 inches (0.10? cm), and is formed
`as a acutely angled projection extending from the man-
`drel element
`54-.
`In a preferred embodiment,
`the
`“threads” which are formed by knife-edge ridge 56 are
`60° angle threads and are disposed at about 8 to about 16
`threads per inch, preferably between about 11 to about
`13 threads per inch (about 4 to 5 threads per centime-
`ter).
`The helical knife-blade ridge 56 is shaped so as to bite
`sufficiently into the metal braid 60 which forms the
`concentric conductor 50 in most coaxial cable. Such a
`helical knife-blade ridge 56 has also been shown to
`provide a secure mechanical attachment to the coaxial
`cable terminus 32 without causing the metallic strands
`which form the braided concentric conductor 50 to
`shear or break off. An effective compromise between
`sharpness and dullness of the knife-blade edge ridge 56
`is to make it flat across for about two to three mils. A
`one mil flat is too sharp and will result in shearing the
`fine wire braid 60, while an eight-mil radius at the edge
`has been found to be too dull with resultant slippage of
`the braid under tension. Ideally, the knife-blade ridge 56
`should subject the braid wires to shear stresses without
`actually resulting in shearing.
`The use of a helical knife-blade ridge 56 on the cable
`attachment moiety 18 of the connection jack connector
`10 has been found to be particularly advantageous in
`order to facilitate easy insulation of the connection jack
`connector 10 onto the coaxial cable 62, especially at low
`ambient temperatures.
`The connection jack connector 10 is made from an
`electrically conductive material, usually a metal. Alumi-
`
`40
`
`45
`
`50
`
`55
`
`60
`
`65
`
`5
`
`10
`
`I5
`
`20
`
`25
`
`30
`
`35
`
`num is a highly preferred such metal because it is light
`weight, inexpensive and highly conductive. Where the
`cable attachment moiety 13 comprises a screw mandrel
`52 and the cable attachment moiety 18 is made from
`aluminum, another conductive material, such as a tin
`alloy, is preferably applied to the exterior of the man-
`drel element 54 to provide additional lubricity to the
`exterior of the mandrel element 54 and to facilitate the
`insertion of the mandrel element 54 into the coaxial
`cable terminus 32.
`
`The swagging shell 12 has an open-ended hollow
`tubular shape. The swagging shell 12 has a compression
`moiety 64 and a retraction moiety 66. The compression
`moiety 64 is adapted to apply hoop stress to the exterior
`of the collet fingers 22 on the connection jack connec-
`tor 10 and the retraction moiety 66 is adapted to inter-
`face with one or more tools adapted to drive the swag-
`ging shell 12 over the collet fingers 22 and/or, alterna-
`tively, to retract the compression moiety 64 off of, and
`away from, the collet fingers 22.
`The compression moiety 64 is generally cylindrical
`and is dimensioned to be slidable over the collet fingers
`22 in such a way as to impart considerable hoop stress to
`the collet fingers 22, thereby causing the collet fingers
`22 to tightly grip the exterior surface 36 of the connec-
`tion jack body 46. For a standard jack having an outside
`diameter of about 0.375 inches (0.95 cm), the inside
`diameter of the compression moiety 64 is typically be-
`tween about 0.40 inches (1.02 cm) and about 0.42 inches
`(1.07 cm), preferably between about 0.41 inches (1.04
`cm) and 0.415 inches (1.054 cm).
`The retraction moiety 66 of the swagging cylinder 12
`is also typically cylindrical. It is attached to the com-
`pression moiety 64 in such a way that the longitudinal
`axes of the compression moiety 64 and the retraction
`moiety 66 are coaxial. The inside diameter of the com-
`pression moiety 64 is dimensioned to allow the retrac-
`tion moiety 66 to slip freely along the outside of the
`coaxial cable 62. In a preferred embodiment, the outside
`diameter of the retraction moiety 66 is dimsioned to
`be slightly smaller than the outside diameter of the
`compression moiety 64 so that an annular shoulder 68 is
`formed at the interface of the retraction moiety 66 and
`the compression moiety 64-. In a typical embodiment,
`the annular shoulder 68 is between about 0.10 inches
`(0.254 cm) and about 0.20 inches (0.51 cm) in width.
`Such annular shoulder 68 provides a surface against
`which an axial force can be applied so as to urge the
`swagging shell 12 over the collet fingers 22.
`In another preferred embodiment, the exterior sur-
`face 70 of the retraction moiety 66 is provided with
`indentations, ridges or other structure capable of pro-
`viding a surface against which a force can be applied to
`the swagging shell 12 to urge the swagging shell 12 off
`of the collet fingers 22. In a most preferred embodi-
`ment, such structure is provided by external screw
`threads 72.
`The swagging shell 12 is made from a rigid material
`capable of withstanding the pressures and wear and tear
`resulting from its interaction with the collet fingers 22
`and with various driving and retraction tools. Typi-
`cally, the swagging shell 12 is made from a metal, such
`as a brass, an aluminum or a steel.
`Where the connection jack connector ll] comprises a
`mandrel element 54 which is physically inserted into the
`coaxial cable terminus 32 (such as the screw mandrel 52
`described above), the swagging shell 12 is preferably
`constructed so that the internal diameter of the retrac-
`
`

`
`9
`tion moiety 66 is smaller than the internal diameter of
`the compression moiety 64, and the interior surface 74
`of the swagging shell 12 at the interface between the
`retraction moiety 66 and the compression moiety 64 is
`beveled. Also, the internal diameter of the retraction
`moiety 66 can be dimensioned so as to apply a compres-
`sive force to the exterior of the cable terminus 52 in the
`region of the terminus 52 wherein has been inserted a
`connection jack connector 10 having a mandrel-type
`connection jack attachment moiety 18. In such an em-
`bodiment, the inside diameter of the retraction moiety
`66 is dimensioned to be about the same or only slightly
`larger than the outside diameter of the cable terminus 32
`after insertion of the mandrel element 54. Such a swag-
`ging shell 12 can be used to apply compressive force to
`the exterior of a coaxial cable terminus 52 having in-
`serted therein a cable attachment moiety 18 comprising
`a mandrel element 54. Such compressive force is effec-
`tive in securing and maintaining a positive electrical
`connection between the concentric conductor 30 of the
`coaxial cable 62 and the mandrel element 54 of the
`connection jack connector cable attachment moiety 18.
`In a preferred method of installing a connection jack
`connector 10 having a mandrel element 54 to the coax-
`ial cable terminus 32, strands of the metal braid 60
`which form the concentric conductor 50, are disposed
`around the exterior of the collet fingers 22 and are held
`fast against the fingers 22 by the compression moiety 16
`of the swagging shell 12. This installation method has
`been found to provide a superior electrical connection
`between the cable attachment moiety 18 of the connec-
`tion jack connector 10 and the concentric conductor 50,
`a connection whic