US2761110A - Solderless coaxial connector - Google Patents

Description

1956 G. G. EDLEN ETAL 2,761,110

SOLDERLESS COAXiAL CONNECTOR Filed Dec. 7, 1955 I5 Sheets-Sheet l 4- 2 42 32 34 5 as .m g i INVENTQRS 60 George G Ed/en cf'fienryl l. D/ambro I I T1 4' WM f/ifl'm SOLDERLESS COAXIAL CONNECTOR Filed D80. 7, 1953 3 Sheets-Sheet 2 INVENTORS George G Ed/cfncf' Hen/"g M O/ambra 28. 1956 e. G. EDL EN' ETAL 2,761,110

SOLDERLESS COAXIAL CONNECTOR Filed Dec. 7, 1953 3 Sheets-Sheet 3 jig? 15' INVENTORS George 6. zf'd/en' Henry M Dl'a/Tlbr'd United States Patent() 2,761,110 SOLDERLESS COAXIAL CONNECTOR George G. Edlen, Silver Spring, Md., and Henry M. Diambra, Washington, D. C.,,assignors to Entron, Inc., Bladensburg, Md., a corporation of Delaware Application December 7, 1953, Serial No. 396,695 13 Claims. (Cl. 339-89) This invention relates to a terminal device for coaxial cable and is particularly useful in connection with a male terminal connector suitable for mating with ,a standard type socket or female connector such as is represented by U. S. military designation 80-239,, (as well as in relation to a coaxial line terminating device. The invention has for its primary object the provision of a simple, in-

expensive and electrically etlicient terminal device which.

can be quickly and permanently attached .to a coaxial cable without the use of solder and, if necessary, without the use of special tools, making it particularly suitable for rapid field or emergency use, as well as for all ordinary uses of such' terminal devices.

It is an object of the invention to provide a terminal device which is mechanically so firmly attached to .a coaxial cable that is impossible to detach it from the cable by any force to which the cable is liable to be subjected in ordinary use, or in effect, by any force which the cable itself can withstand without damage; and which is electrically so well bonded to the cable conductors that no ordinary strain can cause relative slipping or interference with the good electrical connection between the device and the conductors of an attached cable.

It is a further object to provide a coaxial connector plug having extremely high electrical efiiciency, and which can be rapidly correctly assembled to a cable in the field by relatively unskilled personnel; which has a minimum number of parts and is therefore economical to construct; and which mates with standard sockets currently in use.

Another object is to provide a terminal device .for a coaxial cable capable of serving .as a terminating matching impedance for a free end of such cable, and which has all the above recited advantages and is or can be made substantially waterproof in the field, and which uses cssentially the same metal parts as the terminal connection device, thereby simplifying the .constructionof .the'device and reducing its cost.

Another object is the provision of a terminal connector device for a coaxial cable having .the above advantages which can be used in connection with .a double-ended socket device to rapidly and effectively connect two sections of coaxial cable together.

The specific nature of the invention as well as other objects and advantages thereof will clearly :appear from a description of a preferred embodiment as shown in the accompanying drawings, in which:

Fig. 1 is a longitudinal cross-sectionalaview of acoaxial cable fitted with a plug according to .the invention and connected to a standard socket of the 80-239 type;

Fig. 2 is a view partly in cross-section of the pin .connection portion of Fig. 1 taken at right angles to .Fig. 1;

Fig. 3 is a view of a modified form of pin connection;

Fig. 4 is a longitudinal cross-sectional view showing the manner in which two plugs are connected to a doubleended socket to form a cable joint;

Fig. 5 is a longitudinal cross-section view showing the g 2,761 ,1 10 Patented A118.- 28, 1956 manner in which the plug of the invention is converted to a matched impedance line termination;

Fig. 6 is a plan view showing the impedance-matching resistance element of Fig. 5;

Fig. 7 is a side view of the same element, showing the manner in which it is notched to fit onto the plug;

Fig. 8 is a sectional view of a modified form of the impedance-matching resistance element;

Fig. 9 is a cross-sectional view of a modified impedance matching termination; and

Figs. 10 to 14 inclusive show various modified forms of the self-locking ring wedge according to the invention.

Referring to Fig. 1, coaxial cable 2 has outer insulating sheath 4, beneath which is concentric outer braided conductor 6, a concentric layer of high-quality main .insulation 8 such as polyethylene, and a central stranded conductor 10. Terminal member 12 has an outer'shell 14 which has a thin-walled rearwardly extending tube portion 18 which can be slipped as shown beneath braided conductor 6 and around the main insulation 8 which is suitably cut as shown to leave a projecting terminal portion of central stranded conductor 10. Tube 18 is connected to shell 14 by an annular portion 20, and the entire construction is preferably unitary, although it is apparent that 14, 18 and 20 could be three pieces screw-threaded together. Between the rear portion of shell 14 and the forward portion of tube 18 there is thus left an annular space .22. The forward portion of shell 14 constitutes .a cylindrical chamber .in which is a cylinder of insulation 24 surrounding a central bored pin 26. The construction is such that pin 26 vis firmly mechanically bonded to shell 14 by the mass of insulation 24, which may be poured molten into the cylinder chamber which it fills, so that when .it sets it adheres firmly to both shell 14 and pin .26. Alternatively, pin 26 and cylinder '24 may be formed as .a mechanically integrated unit and placed into the-chamber in shell 14, the top edge of the shell being .then staked .or turned .to firmly retain the cylinder and pin in .the .shell.

Pin 26 is centrally bored .to .freely receive central stranded conductor 10 of the cable. Near the tip of pin 26, .it :is reduced .in diameter as shown .at,2-8, ,to provide a thin-walled portion of the pin which can be readily deformed by any suitable tool, such as a pair of pliers, as shown at 30, to provide a good .crimped connection both electrically and mechanically between the pin and conductor 10. The thin-walled construction of the .reduced portion is such that the deformation shown in Fig. 1 will cause a bulge perpendicular to the planeof the drawing, .but this bulge will not extend out beyond .the major external diameter of the pin, as shown in Fig. 2, which is taken at right angles to Fig. 1. Thus pin 26 can mate with the bored and split center pin 32 of socket 34, even after it has been .crimped .at 30 with sufficient deformation to insure .an excellent electrical .and mechanical connection between the pin and .central .conductor .10.

Socket 34 is shown mountedon a .panel 36 by means of rivets .38 and comprises an .outer threaded shell 40 containing insulating cylinder .42 which firmly holds .the split .pin -32. The split pin 32 maybe bored and .terminated in conventional fashion to facilitate soldering of a wire thereto, this all being .a known construction ofthe type designated in military nomenclature as socket S0439.

A nut 44 *interally threaded at 4.6 is provided for threaded engagement :with the socket .34. The rearward portion of the nut is provided with .an aperture 46 .of slightly'greater.diameter than cable 2. Where .theouter sheath 4 is slipped .over tube -18, it =bulges ,out OPVCI' tube 18 .as shown, and due .to this bulge .the sheath 4 firmly engages the inner edge of aperture 46 to provide a substantially weather-tight connection at this point.

An annular ring wedge 48 provided with a flange 50, is inserted into annular space 22. The braided portion 6 of the cable is extended beyond the cut edge 52 of outer sheath 4, and is flared out slightly by hand, which can easily be done because of the looseness of the braiding; this flared portion is then rolled back on itself in annular space 22 as shown. Ring wedge 43 has previously been placed about the cable and is now brought forward and forced into annular space 22, thus wedging the braided portion firmly against the inner walls of the annular space 22. Nut 44 which was placed on the cable before ring wedge 48 can now be brought forward, but first the center stranded conductor 10, which has been threaded into pin 26 at the same time tube 18 received the cable 2, is now cut off flush with the end of pin 26 (since usually it is left longer than the pin to insure that it extends past reduced portion 28) and the pin is crimped at 30. Now,

when nut 44 is threaded up on shell 40, ring wedge 48 is forced home into annular space 22 to complete the connection. In the event that the connector is not to be connected immediately with a socket, a spare socket can be used to draw up nut 44 and force home wedge 48, or alternatively, the wedge can be forced into place by means of any suitable tool, such as a pair of ordinary pliers. If desired, a special tool may obviously be made to force the ring wedge home, and where a large number of cables are prefabricated with the connector shown in Fig. 1, the provision of such a special tool may be advantageous in order to facilitate assembly of the fitting.

Shell 14 is provided with two or more tits 52 to mate with the edge serrations usually provided on shell to prevent relative rotation of shells 14 and 40 once they are engaged. A dab of waterproofing compound may be applied around flange prior to assembly to insure weather-tightness, or suitable gaskets may be used for this purpose if desired.

The front end of pin 26 may be slightly rounded as shown in Fig. l, or the pin may be slightly tapered as shown at 54 in Fig. 3 to engage with a similarly tapered socket pin 56, which may also be split as shown, if desired, or reliance may be placed on a tight tapered fit between these two members. Note that by making the maximum diameter of point 54 no greater than that of pin 26, the pin will still mate with a standard socket of the 50-239 type, as well as with a socket having a tapered pin 56.

Fig. 4 shows how two plugs similar to that shown in Fig. 1 can be used with a special double-ended socket to join two coaxial cables. Socket is merely a doubleended version of the 50-239 type, preferably with a flange 62 whereby it can be held relative to the external nuts 64 and 66 of the two plugs which are to be joined. Suitable waterproof gaskets 68 may be used to prevent entrance of moisture, or else waterproof composition may be applied to achieve the same result. Pin 70 is bored and double-ended to receive two plug pins for completing the central conductor connection, while the outer conductor connection is completed through nuts 64 and 66 and the outer shell 72 of the double-ended socket. Thus a highly efficient joint is provided which can be readily assembled in the field without the use of solder or special tools, although, as previously stated, special tools may be readily constructed to facilitate the assembly process.

Fig. 5 shows how the plug may be used to achieve a coaxial termination having an impedance matched to the characteristic impedance of the line, which is required in a coaxial termination for maximum efiiciency. Annular disc 80, having a radial resistance between its inner and outer edges corresponding to the desired terminating impedance is placed over pin 26. The central bore of disc 80 is dimensioned so that a slight press fit over pin 26 is effected, in order to insure good electrical contact.

In practice, the conductive parts (including the pin 26) of the plug are usually silver-plated to provide good electrical contact, and the inner surface 82 of the disc is preferably also silver-coated, as by painting or deposition, so that good electrical contact is readily achieved. Similarly, the outer surfaces of disc are silver-coated at 84 and 86 to insure good contact with shell 14 and cap nut 88 which is threadedly connected to plug nut 44 of the plug. The interior surface of cap nut 88 is spaced at all points from any part of pin 26 by a distance greater than the radial distance between the central conductor 10 and braid 6 of coaxial cable, to minimize capacitive coupling between the pin 26 and the outer conductor. Radial grooves 90 are provided on the under side of disc 80 to mate with tits 52 on shell 14, so that the main bearing surface 86 of the disc rests against the upper edge of nut 14. Since groove 90 prevents rotation of disc 80, as cap nut 88 is tightened on the disc, a good sliding contact is effected between cap nut 88 and the surface of the disc, so that if desired, conducting surfaces 84 and 86 can be omitted. For the same reason, a water-tight gasket, suitably shaped to fit grooves 90 as well as the edge portion of the disc, may be substituted for conducting surface 86, since adequate contact is provided at surface 84.

Since disc 80 is relatively fragile and may be damaged by too great pressure being put on cap nut 88, the outer and inner edge of the disc may be made of metal, if desired, as shown in diametrical cross-section in Fig. 8 at 92 and 94, the resistive portion of the disc being molded between the two metal rings 92 and 94. If desired, the upper surface of the disc may be coated with insulation, or a heavy disc 96 of insulating material may be adhered to the disc for extra protection.

It will be apparent that a selection of discs 80 of variout resistance values may be carried about in the field, and the assembly made up on the spot with the proper matching impedance to suit the circuit requirements. The annular impedance of disc 80 is ideally suited for coaxial termination, as it is radially and circumferentially symmetrical, and introduces minimum losses. Thus, by carrying a supply of cap nuts 88 and discs 80, the plug may be immediately used either for a connector plug or for a matched impedance terminal. If it is subsequently desired to extend the line or to attach it to other equipment, the cap nut 88 is merely removed, and a wrench placed on the outer edge of disc 80 and Worked angularly back and forth to loosen disc 80 so that it can be re moved from pin 26, and the plug is ready for use as a connector.

Fig. 9 shows an alternative form of terminal fitting wherein the disc 80 is embedded in the cylindrical insulation block 24. This is suitable for use in a permanent terminal fitting, but must be cut off and a new fitting like that of Fig. 1 inserted if it is desired to change to a connector plug termination.

The construction shown in Fig. 1 wherein nut 44 retains ring wedge 50 against any pull on the cable has been found to be very effective, the wedge action of the ring 50 forcing the braided conductor into excellent permanent electrical connection with the walls of the annular aperture of shell 14, and any pull on the cable is resisted partly by this frictional engagement between the braid and the shell and partly by the effect of nut 44 in locking the ring wedge into place. Without this locking action of nut 44, the maximum resistance of ring wedge 48 to a pull on the cable is not obtained. It may be desirable in some situations to use the ring wedge con struction without the outer nut 44, and for this type of use it is desirable to modify the ring wedge and shell construction as shown in Figs. 10 and 11, in which the ring wedge 48' is provided with reentrant flange 96 which fits over reduced rear portion 98 of shell 14', corresponding to shell 14 of Figs. 1. The assembly is then staked as shown at 100, which may be done with any convenient punch or a special pair of staking pliers made to perform this operation on two diametrically opposed sides of the fitting. Alternatively, a snap lock may be employed as will be clear from Figs. 11 and 12 where reentrant flange 96 is slotted and undercut to catch on a similar undercut on reduced portion 98 of shell-"14". Still another method of holding the ring wedge is shown in Figs. 13 and 14 Where two lugs 102 protruding from the bottom of shell 14 pass through slots 1-04 milled in the edge of flange 50 of the ring wedge and are bent over to hold the ring wedge in place.

It will be understood that the same reference numeral with primes added is used to indicate corresponding elements in the various modifications, where the element is slightly modified, but where the element is unmodified, the same reference number is used as in Fig. 1.

It will be apparent that the embodiments shown are only exemplary and that various modifications can be made in construction and arrangement within the scope of the invention as defined in the appended claims.

We claim:

1. A male coaxial cable connector for a coaxial cable having a central conductor, a concentric flexible outer conductor and at least one concentric intermediate layer of insulation between said conductors, said connector comprising an insulating member, a central pin of substantially uniform cylindrical configuration supported by said insulating member and having a bore to freely receive the central conductor of an attached cable, a unitary outer shell rigidly enclosing and supporting said insulating member whereby said insulating member holds and maintains said central pin and outer shell in coaxial alignment, said pin projecting forwardly beyond said insulating member and said shell for engagement with a mating female conductor, said pin having an annular concentric reduced portion near the forwardly projecting end thereof, said reduced portion constituting a relatively thin-walled section deformably pinched about an engaged central conductor of a coaxial cable without any part of the pinched portion extending beyond the cylindrical configuration of the pin, said outer shell having a tubular portion thereof extending rearwardly beyond said insulating member, and an annular wedge ring extending into said rearwardly extending tubular portion, said ring being dimensioned to loosely fit in said tubular portion for wedging the braided outer conductor of a coaxial cable therein.

2. The invention according to claim 1, and an internally threaded outer nut loosely movable about said shell, said nut having a radially inwardly extending flange for engaging said wedge ring.

3. A male coaxial cable connector for a coaxial cable having a central conductor, a concentric flexible outer conductor and at least one concentric intermediate layer of insulation between said conductors, said connector comprising an insulating member, a central pin of substantially uniform cylindrical configuration supported by said insulating member and having a bore to freely receive the central conductor of an attached cable, a unitary outer shell rigidly enclosing and supporting said insulating member whereby said insulating member holds and maintains said central pin and outer shell in coaxial alignment, said pin projecting forwardly beyond said insulating member and said shell for engagement with a mating female conductor, said pin having an annular concentric reduced portion near the forwardly projecting end thereof, said reduced portion constituting a relatively thin-walled section crimpable about an engaged central conductor of a coaxial cable, said outer shell having a portion thereof extending rearwardly beyond said insulating member and a radially inwardly extending portion abutting the insulating member, said inwardly extending portion having a central perforation for receiving the intermediate layer of insulation of an attached coaxial conductor, a thin-walled tubular member extending rearwardly from said inwardly extending portion and having a bore for receiving said intermediate layer of insulation, whereby an annular channel is formed between the outside of the forward portion-of said tubular member and the innerside of the rearwardly extending portion of said shell, an annular wedge ring extending into said channel, said ring being dimensioned to loosely fit in said annular channel for wedging the braided outer conductor of a coaxial cable therein.

4. The invention according to claim 3,, and an internally threaded outer nut loosely movable about said shell, said nut having a radially inwardly extending flange for engaging said Wedge ring.

5. The invention according to claim 4, said central pin terminating in a tapered forward portion for engagement with a correspondingly tapered female connector portion.

6. The invention according to claim 4, and a female coaxial cable connector engaged with said male connector, said female connector having an insulating member, a bored central portion supported intermediate its ends by said insulating member, the forward portion of said bored central portion being longitudinally split and of a diameter to frictionally receive the central pin of said male connector, and an outer shell supporting'said insulating member, said outer shell being externally threaded to engage said internally threaded outer nut.

7. The invention according to claim 4, and a hollow cap member externally threaded to engage with said internally threaded outer nut, the interior surface of said cap member being spaced at all points thereof from the surface of said central pin by a distance at least equal to the radial distance between the surface of said central in and the inner surface of said shell portion.

8. The invention according to claim 7, and a disc of resistive material extending between said central pin and said outer shell, said disc being imbedded in said insulating member.

9. The invention according to claim 7, and a disc of resistive material extending between said central pin and said outer shell, said disc abutting the forward portion of said insulating member and engaging both said shell member and said cap member.

10. The invention according to claim 3, said wedge ring having a rearwardly disposed radially outwardly extending flange.

11. The invention according to claim 10, the flange of said wedge ring having at least one radially extending slot, and said shell having at least one tab extending rearwardly through said slot and bent radially inwardly to hold said ring in said annular channel.

12. The invention according to claim 10, the flange of said Wedge ring having a forwardly extending cylindrical portion :of an internal diameter to receive the rearwardly extending shell portion therein. and means for fastening said cylindrical portion to the received shell portion.

13. A coaxial cable connector for a coaxial cable having a central conductor, a concentric flexible outer conductor, and at least one concentric intermediate layer of insulation between said conductors, said connector comprising an insulating member, a central pin supported by said insulated member and having a bore to receive the central conductor of an attached cable, a unitary outer shell enclosing said insulating member, said outer shell having a portion thereof extending rearwardly beyond said insulating member and a radially inwardly extending portion abutting the insulating member, said inwardly extending portion having a central perforation for receiving the intermediate layer of insulation of an attached coaxial conductor, a thin-walled tubular member extending rearwardly from said inwardly extending portion and having a bore coextensive with the perforation thereof for receiving said intermediate layer of insulation, whereby an annular channel is formed between the outside of the forward portion of said tubular member and the inner side of the rearwardly extending portion of said shell,

' 7 an annular wedge ring extending into said channel, said ring being dimensioned to loosely fit in said annular channel for wedging the braided outer conductor of a coaxial cable therein.

References Cited in the file of this patent UNITED STATES PATENTS 8 Morris et a1 June 22, 1948 Rieke June 14, 1949 Wetherill Feb. 14, 1950 Hunt Feb. 21, 1950 Buchanan Feb. 28, 1950 Feenberg Jan. 23, 1951 Puerner Sept. 9, 1952 FOREIGN PATENTS Great Britain Apr. 13, 1945

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