Abstract:
Coaxial connectors include a connector body and an inner contact post mounted therein. These connectors further include a compression element that is configured to impart a generally circumferential compressive force to secure one or more elements of a coaxial cable between the connector body and the inner contact post, and an internally threaded rotatable nut that is configured for attachment to the connector body. In some embodiments, the nut has a first set of threads and a second set of threads that is immediately adjacent to the first set of threads, where the threads of the second set of threads are configured to provide increased drag and mechanical resistance as compared to threads of the first set of threads when the rotatable nut is threaded onto a female coaxial cable port. In other embodiments, an internal diameter of the threaded portion of the nut varies along the axial direction. In still other embodiments, a bushing is mounted within the threaded region of the nut.

Description:
FIELD OF THE INVENTION 
       [0001]    The present invention relates generally to communications connectors and, more particularly, to connectors for coaxial cables. 
       BACKGROUND 
       [0002]    Coaxial cables are a specific type of electrical cable that may be used to carry information signals such as television or data signals. Coaxial cables are widely used in cable television networks and to provide broadband Internet connectivity.  FIGS. 1 and 2  are, respectively, a transverse cross-sectional view and a longitudinal cross-sectional view of a conventional coaxial cable  10  ( FIG. 2  is taken along the cross section  2 - 2  shown in  FIG. 1 ). As shown in  FIGS. 1 and 2 , the coaxial cable  10  has a central conductor  12  that is surrounded by a dielectric  14 . A tape  16  is preferentially bonded to the dielectric  14 . The central conductor  12 , dielectric  14  and tape  16  comprise the core  18  of the cable. Electrical shielding wires  20  and, optionally, electrical shielding tape(s)  22  surround the cable core  18 . Finally, a cable jacket  24  surrounds the electrical shielding wires  20  and electrical shielding tape(s)  22 . As shown in  FIG. 2 , the dielectric  14 , tape  16 , electrical shielding wires  20 , electrical shielding tape  22  and cable jacket  24  may be cut, and the electrical shielding wires  20 , electrical shielding tape  22  and cable jacket  24  may be folded back, in order to prepare the coaxial cable  10  for attachment to certain types of coaxial connectors. 
         [0003]    Coaxial connectors are a known type of connector that may be used to connect two coaxial cables  10  or to connect a coaxial cable  10  to a device (e.g., a television, a cable modem, etc.) having a coaxial cable interface. Coaxial “F” connectors (herein “F-style coaxial connectors”) are a specific type of coaxial connector that may be used to terminate a coaxial cable. As is known to those of skill in the art, F-style coaxial connectors are a male connector that mate with female coaxial cable ports. 
         [0004]      FIG. 3  is a perspective view of a conventional F-style coaxial connector  30 .  FIG. 4  is a side cross-sectional view of the prior art coaxial “F” connector of  FIG. 3 .  FIG. 5  illustrates the connector  30  of  FIG. 3  after it has been attached to an end of a coaxial cable  10 . As shown in  FIGS. 3 and 4 , the connector  30  includes a tubular connector body  32 , a compression sleeve  34 , an inner contact post  36  and an internally threaded nut  38 . As shown in  FIG. 5 , the coaxial cable  10  is inserted axially into the inside diameter of the tubular connector body  32  and the compression sleeve  34 . Referring to  FIG. 4 , the core  18  of the coaxial cable  10  inserts axially into an inside diameter of the inner contact post  36 , while the electrical shielding wires/tape  20 / 22  and the cable jacket  24  circumferentially surround the outer surface of the inner contact post  36  (the cable  10  is not shown in  FIG. 4 ). The outside surface of the inner contact post  36  may include one or more serrations, teeth, lips or other retention structures  37  (see  FIG. 4 ). Once the cable  10  is inserted into the connector  30  as described above, a compression tool may be used to axially insert the compression sleeve  34  further into the tubular connector body  32  into the position shown in  FIG. 5 . The compression sleeve  34  directly decreases the radial gap spacing between the connector body  32  and the inner contact post  36  so as to radially impart a 360-degree circumferential compression force on the electrical shielding wires/tape  20 / 22  and the cable jacket  24  that circumferentially surround the outer surface of inner contact post  36 . This compression, in conjunction with the retention structures  37  on the outside surface of the inner contact post  36 , applies a retention force to the coaxial cable  10  that holds the cable  10  within the connector  30 . As shown in  FIG. 5 , the central conductor  12  of the coaxial cable  10  extends into the internal cavity of the nut  38  to serve as the male protrusion of the connector  30 . 
         [0005]    As is known to those of skill in the art, F-style coaxial connectors are used to mechanically and electrically attach a coaxial cable such as cable  10  to a female coaxial cable port such as, for example, a standard coaxial cable wall outlet or a port on an electronic device such as a cable-ready television set.  FIG. 6  is a perspective view of a conventional female coaxial cable port  40 . As shown in  FIG. 6 , the female coaxial cable port  40  may comprise a cylindrical port that has an at least partially threaded external surface  42 . The distal end of the cylinder includes an aperture  44  that receives the central conductor  12  of a mating F-style coaxial connector  30 . The rotatable nut  38  of a mating connector  30  is inserted over, and threaded onto, the female coaxial cable port  40  so that the central conductor  12  of the coaxial cable  10  that is attached to the connector  30  is received within the aperture  44 , thereby mechanically and electrically connecting coaxial cable  10  to the female coaxial cable port  40 . 
       SUMMARY 
       [0006]    Pursuant to embodiments of the present invention, coaxial connectors are provided that include a connector body, an inner contact post that is at least partly within the connector body, and a compression element that is configured to impart a generally circumferential compressive force to secure one or more elements of a coaxial cable between the connector body and the inner contact post when the compression element is in a seated position. These connectors further include an internally threaded rotatable nut having a first set of threads and a second set of threads that is immediately adjacent to the first set of threads. The threads of the second set of threads are configured to provide increased drag and mechanical resistance as compared to threads of the first set of threads when the rotatable nut is threaded onto a female coaxial cable port. In some embodiment of these coaxial connectors, the second set of threads may include at least some of the four threads that are located closest to the inner contact post. 
         [0007]    In some embodiments, the second set of threads may comprise tipped threads that have a thread angle that is offset from 90 degrees such as, for example, a thread angle that is offset from 90 degrees by between about 2 degrees and about 10 degrees. In other embodiments, the second set of threads may be tipped threads in which the major diameter and/or the minor diameter of the threads are decreased relative to the threads of the first set of threads so as to provide increased drag and mechanical resistance when the rotatable nut is threaded onto a female coaxial cable port. 
         [0008]    In other embodiments, the second set of threads may be pipe threads. In still other embodiments, the second set of threads may be threads that include at least one defect such as, for example, a defect that is formed by applying an external force to the outside surface of the nut opposite the internal threads that forms a dimple in the outside surface of the nut. In the above-described embodiments, the nut may be formed of a material including bronze, and the seal that is created when the nut is threaded onto the female coaxial cable port may be a reversible seal that can be reversed via hand rotation of the nut. 
         [0009]    Pursuant to further embodiments of the present invention, coaxial connectors are provided that include a connector body, an inner contact post that is at least partly within the connector body, and a compression element that is configured to impart a generally circumferential compressive force to secure one or more elements of a coaxial cable between the connector body and the inner contact post when the compression element is in a seated position. These connectors further include an internally threaded rotatable nut that is attached to the connector body, where the internal diameter of the threaded portion of the nut varies along the axial direction. 
         [0010]    In some embodiments, the internal diameter is only varied over a subset of the threaded portion of the nut. For example, the internal diameter may be varied with respect to only (or at least) some of the four threads of the nut that are located closest to the contact post. The internal diameter may vary, for example, by between about 1% and about 3%. 
         [0011]    Pursuant to still further embodiments of the present invention, coaxial connectors are provided that include a connector body, an inner contact post that is at least partly within the connector body, and a compression element that is configured to impart a generally circumferential compressive force to secure one or more elements of a coaxial cable between the connector body and the inner contact post when the compression element is in a seated position. These connectors further include an internally threaded rotatable nut that has a threaded region that includes a plurality of internal threads and a bushing that is mounted within the threaded region of the nut. 
         [0012]    In some embodiments, the bushing may be located between a first subset of the plurality of internal threads and a second subset of the plurality of internal threads. The bushing may comprise, for example, a nylon or plastic annular bushing or a nylon or plastic plug that extends less than 90 degrees around the internal diameter of the nut. The bushing may be positioned such that when the nut is threaded onto a female coaxial cable port, a leading thread of the female coaxial cable port that is closest to a distal end of the female coaxial cable port will come into contact with the bushing within one to three full rotations of the nut before the distal end of the female coaxial cable port contacts the connector body. In some embodiments, no more than four threads are interposed between a first surface of the bushing that is closest to the contact post and an end of the nut that is closest to the contact post. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0013]      FIG. 1  is a transverse cross-sectional diagram of a conventional coaxial cable. 
           [0014]      FIG. 2  is a longitudinal cross-sectional diagram of the conventional coaxial cable of  FIG. 1 . 
           [0015]      FIG. 3  is a perspective view of a prior art F-style coaxial connector that has a compression style back fitting with the compression sleeve in a unseated position. 
           [0016]      FIG. 4  is a side cross-sectional view of the prior art F-style coaxial connector of  FIG. 3 . 
           [0017]      FIG. 5  is a perspective view of the prior art F-style coaxial connector of  FIG. 3  mounted on a coaxial cable. 
           [0018]      FIG. 6  is a perspective view of a conventional female coaxial cable port. 
           [0019]      FIG. 7  is a perspective view of a F-style coaxial connector according to certain embodiments of the present invention. 
           [0020]      FIG. 8  is an exploded perspective view of the F-style coaxial connector of  FIG. 7  with certain components thereof shown in a cutaway view. 
           [0021]      FIG. 9  is a side view of the connector of  FIG. 7  in assembled form. 
           [0022]      FIG. 10  is a side view of the connector of  FIG. 7  with the compression sleeve partially removed. 
           [0023]      FIG. 11  is a side view of the connector of  FIG. 7  fully disassembled. 
           [0024]      FIG. 12  is a perspective view of an internally threaded nut for an F-style coaxial connector that includes tipped threads according to certain embodiments of the present invention. 
           [0025]      FIG. 13  is a cross-sectional view of the nut of  FIG. 12  taken along the line  13 - 13  in  FIG. 12 . 
           [0026]      FIG. 14  is a schematic diagram showing how tipped threads having a thread angle that varies from 90 degrees may be formed. 
           [0027]      FIG. 15  is an enlarged cross-sectional view of the threads of a nut according to further embodiments of the present invention that has tipped threads in which the minor diameter has been decreased. 
           [0028]      FIG. 16  is a perspective view of a nut for an F-style coaxial connector according to further embodiments of the present invention that includes pipe threads. 
           [0029]      FIG. 17  is a cross-sectional view of the nut of  FIG. 16  taken along the line  17 - 17  in  FIG. 16 . 
           [0030]      FIG. 18  is an enlarged cross-sectional view of a small portion of the threads of the nut of  FIGS. 16-17  after the nut has been mated with a female coaxial connector port. 
           [0031]      FIG. 19  is a side cutaway view of a nut for an F-style coaxial connector according to still further embodiments of the present invention that includes at least one bushing. 
           [0032]      FIG. 20  is a side cross-sectional view of an F-style coaxial connector according to additional embodiments of the present invention that includes a different bushing. 
           [0033]      FIG. 21  is a perspective view of a nut for an F-style coaxial connector according to further embodiments of the present invention that has an internal diameter that is cut with a slight chamfer. 
           [0034]      FIG. 22  is a cross-sectional view of the nut of  FIG. 21  taken along the line  22 - 22  in  FIG. 21 . 
           [0035]      FIG. 23  is a perspective view of a dimpled nut for an F-style coaxial connector according to further embodiments of the present invention. 
           [0036]      FIG. 24  is a cross-sectional view of the nut of  FIG. 23  taken along the line  24 - 24  in  FIG. 23 . 
           [0037]      FIG. 25  is a cross-sectional view of another type of F-style coaxial connector that may include nuts according to embodiments of the present invention. 
           [0038]      FIGS. 26-27  are an exploded perspective view and a cross-sectional view, respectively, of yet another type of F-style coaxial connector that may include nuts according to embodiments of the present invention. 
           [0039]      FIG. 28  is a cross-sectional diagram of a portion of a nut that is mated with a bolt that illustrates the thread profiles for a Unified Thread Standard compliant nut and the bolt. 
       
    
    
     DETAILED DESCRIPTION 
       [0040]    The present invention now is described more fully hereinafter with reference to the accompanying drawings, in which preferred embodiments of the invention are shown. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. 
         [0041]    In the drawings, the size and/or relative positions of lines and elements may be exaggerated for clarity. It will also be understood that when an element is referred to as being “coupled” to another element, it can be coupled directly to the other element, or intervening elements may also be present. In contrast, when an element is referred to as being “directly coupled” to another element, there are no intervening elements present. Likewise, it will be understood that when an element is referred to as being “connected” or “attached” to another element, it can be directly connected or attached to the other element or intervening elements may also be present. In contrast, when an element is referred to as being “directly connected” or “directly attached” to another element, there are no intervening elements present. The terms “upwardly”, “downwardly”, “front”, “rear” and the like are used herein for the purpose of explanation only. 
         [0042]    Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. The terminology used in the description of the invention herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. As used in the description of the invention and the appended claims, the singular forms “a”, “an” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. As used herein, the term “and/or” includes any and all combinations of one or more of the associated listed items. 
         [0043]    As is discussed below, pursuant to embodiments of the present invention, coaxial “F” connectors are provided which have rotatable nuts that are designed to exhibit increased drag and mechanical resistance. Before describing these nuts it is helpful to define certain properties of threads for nuts and bolts that comply with the Unified Thread Standard or “UTS”, which is a standard that defines the profile for screw threads that are commonly used in the United States and Canada. In particular,  FIG. 28  is a cross-sectional diagram of a portion of a nut  900  that is mated with a bolt  910  that illustrates the thread profiles for a UTS-compliant nut and the bolt. 
         [0044]    As shown in  FIG. 28 , the threads for both the nut  900  (i.e., the “internal” thread) and the bolt  910  (i.e., the “external thread”) are symmetric V-shaped threads. As shown in  FIG. 28 , the centerline of each thread bisects the longitudinal axis of the bolt  910  at an angle of 90 degrees (herein the “thread angle”). In the plane of the thread axis, the flanks of the V on each thread form a 60 degree angle. The outermost ⅛ th  of each external thread (i.e., the threads on the bolt  910 ) are cut off so that the peak of each thread on the bolt  910  has a flat profile. The innermost ¼ of each internal thread (i.e., the threads on the nut  900 ) are cut off so that the peak of each thread on the nut  900  similarly has a flat profile. 
         [0045]    The threads are further defined by their major diameter D max , their minor diameter D min  and their pitch P (i.e., the distance that a screw advances during a 360 degree rotation). For an external thread (i.e., the threads on the bolt  910 ), the major diameter D max  and the minor diameter D min  are maximum dimensions. Thus, for an external thread to be standards compliant, the major diameter D max  and the minor diameter D min of the threads must be less than or equal to the specified values in the standard. As shown in  FIG. 28 , an external thread may have a major diameter D max  and/or a minor diameter D min  that is less than called for by the standard (e.g., the minor diameter of thread  912  has been rounded out so that it is less than the value D min  that is specified in the UTS standard). For an internal thread to be standards compliant, the major diameter D max  and the minor diameter D min  of the threads must be greater than or equal to the specified values in the standard. As shown in  FIG. 28 , an external thread may have a major diameter D max  and/or a minor diameter D min  that is less than called for by the standard (e.g., the minor diameter of thread  912  has been rounded out so that it is less than the value D min  that is specified in the UTS standard). The distance D min  defines the internal diameter of the nut  900 . 
         [0046]    F-style coaxial connectors are commonly used in homes and other premises to connect televisions and cable modems to wall-mounted female coaxial cable ports. As the television sets and/or cable modems are moved, axial or other forces may be applied to the coaxial cable that can loosen the connection between one or both of the F-style coaxial connectors on either end of the cable and the female coaxial cable ports with which they are mated. By way of example, televisions that are mounted on a swiveled base may be swiveled repeatedly during ordinary use. This rotation can apply axial forces on the coaxial cable that connects to the female coaxial cable port on the television which, over time, can loosen the connection. As the connection is loosened, the cable television signal carried by the coaxial cable may be degraded and/or lost. 
         [0047]    Typically, when an F-style coaxial connector is tightened by hand onto a female coaxial cable port, the installer will apply a force of approximately 3-4 inch/lbs. to the rotatable nut on the coaxial connector. Such a force, however, may not be sufficient to prevent the coaxial connector from being loosened when subjected to forces that may be applied during normal operation. In order to prevent such loosening, it has been recommended that a force of 20-40 inches/lb. be applied to an F-style coaxial connector when it is attached to a female coaxial cable port. However, the female coaxial cable ports on televisions, cable modems and other consumer electronic devices may not always be rated to withstand such forces, and thus there is a reluctance to tighten the F-style coaxial connector using forces of 20-40 inches/lb. for fear that an expensive electronic component may be damaged if the female coaxial cable port on the equipment cannot withstand such a force. 
         [0048]    Pursuant to embodiments of the present invention, coaxial “F” connectors are provided which have rotatable nuts that are designed to exhibit increased drag and mechanical resistance. As such, once installed on a female coaxial cable port, the F-style coaxial connectors according to embodiments of the present invention will resist loosening, and therefore may provide a more robust mechanical connection and/or improved electrical performance over time. The rotatable nuts on the F-style coaxial connectors disclosed herein may use one or more of a variety of different retention mechanisms such as tipped threads, pipe threads, internal bushings, chamfered internal diameters and/or dimples to provide the increased drag and mechanical resistance. 
         [0049]      FIG. 7  is a perspective view of an F-style coaxial connector  100  on which the rotatable nuts according to certain embodiments of the present invention may be used.  FIG. 8  is an exploded perspective view of the F-style coaxial connector  100  with certain components thereof shown in a cut-away view.  FIGS. 9-11  are side views of the connector  100  in various states of assembly. 
         [0050]    As shown in  FIGS. 7-11 , the connector  100  includes a tubular connector body  110 , a compression sleeve  130 , an inner contact post  150  and an internally threaded rotatable nut  170 . As shown in  FIG. 8 , the connector body  110  includes a top end  112  and a bottom end  114 , and the compression sleeve  130  likewise includes a top end  132  and a bottom end  134 . When inserted into the connector body  110 , the compression sleeve  130  circumferentially surrounds an upper portion  152  of the inner contact post  150 . 
         [0051]      FIGS. 9-11  illustrate the connector  100  in various states of assembly. In  FIGS. 9-11 , the cable  10  has been omitted in order to simplify the drawings.  FIG. 9  illustrates how the connector appears once the compression sleeve  130  has been inserted into the connector body  110  in order to lock the cable  10  into place.  FIG. 10  illustrates how the connector appears before it is terminated onto a cable. The connector body  110  may include grooves or recesses (not visible in  FIGS. 9-11 ) and the compression sleeve  130  may include detents or other raised surfaces (one such detent  136  is visible in  FIGS. 10-11 ) that mate with the grooves in order to hold the compression sleeve  130  in place within the connector body  110 . As a result, the connector  100  may readily be maintained as a single piece unit until such time as a cable  10  is to be attached to the connector  100 . The mating raised surfaces/recesses may be designed to only apply a small retention force so that the compression sleeve  130  may be readily moved into the position of  FIG. 9  when terminating a cable  10  with the connector  100 .  FIG. 11  is an exploded side view of the connector  100  which more clearly shows the alignment of the inner contact post  150 , the internally threaded nut  170 , the connector body  110  and the compression sleeve  130 . As is also shown in  FIG. 11 , an optional O-ring or other type of seal  180  may be provided to enhance the moisture seal. 
         [0052]    In order to terminate the connector  100  onto the end of a coaxial cable  10 , the cable  10  is first prepared as shown in  FIG. 2  by cutting away and removing end portions of the dielectric  14 , the tape  16 , the electrical shielding wires  20 , the electrical shielding tape  22  and the cable jacket  24  so that the end portion of the central conductor  12  is fully exposed. An additional end portion of the cable jacket  24  is then removed, and the end portions of the electrical shielding wires/tape  20 / 22  are flared or folded back in whole or in part over the remainder of the cable  10 . The core  18  of the cable  10  is then axially inserted through the compression sleeve  130  and into the inner diameter of the inner contact post  150 , while the electrical shielding wires/tape  20 / 22  and the cable jacket  24  are inserted through the compression sleeve  130  and over the outside surface of the inner contact post  150 . The exposed length of the central conductor  12  core is sufficient such that it will extend all the way through the connector  100  and extend into the internally threaded nut  170  of the connector  100  as the male contact protrusion of the connector. 
         [0053]    During this insertion process, the connector  100  may be in the assembly state shown in  FIG. 10 . Once the cable  10  is received within the connector  100 , a compression tool may be used to fully insert the compression sleeve  130  into the connector body  110  so that the connector assumes the position of  FIG. 9 . The inner diameter (not visible in  FIGS. 7-11 ) of the upper end  132  of the compression sleeve  130  may have a smaller radius than the inner diameter of the lower end  134  of the compression sleeve  130 . A ramped transition section may connect the inner radii of the upper and lower ends of the compression sleeve  130 . As the compression sleeve  130  is driven into the connector body  110 , the gap between the inside diameter of the compression sleeve  130  and the jacket  24  of the cable  10  is reduced and ultimately disappears as the upper end  132  of the compression sleeve (with the reduced circumference) is forced over the cable jacket  24 . Thus, once the compression sleeve  130  is fully inserted and seated within the connector body  110 , the compression sleeve  130  imparts a 360-degree compression force on the jacket  24 . 
         [0054]    As noted above, pursuant to embodiments of the present invention, rotatable nuts for F-style coaxial connectors are provided that exhibit increased drag and mechanical resistance once the connector is mated with a female coaxial cable port. A number of different embodiments of such nuts are described below with reference to  FIGS. 12-24 . Any of these nuts may be used with the connector  100  of  FIGS. 7-11  to provide an F-style coaxial connector according to embodiments of the present invention. 
         [0055]      FIGS. 12 and 13  are a perspective view and a cross sectional view, respectively, of one such internally threaded nut  200  that includes “tipped” threads that provide such increased drag and mechanical resistance. The nut  200  could be used, for example, as the nut  170  in the connector  100  of  FIGS. 7-11 . As shown in  FIG. 12 , the nut  200  includes a relatively narrow first end  210  and a relatively wider second end  220  that has a hexagonal-shaped exterior that may receive the end of a wrench. As shown in  FIG. 13 , the internal surface of the first end  210  is internally threaded, having a first set of threads  212  and a second set of threads  214 . The first set of threads  212  may be standard threads, while the second set of threads  214  may be “tipped” threads. In the depicted embodiment, the tipped threads  214  are the last four threads that are closest to the relatively wider second end  220  of the nut  200 . 
         [0056]    Herein, the term “tipped” threads refers to nut threads that have (1) a thread angle that is offset from 90 degrees or (2) major diameters and/or minor diameters that are less than the values called for by the UTS standards. By way of example, the thread angle can be offset from 90 degrees by angling the internal threads  902 ,  904  in  FIG. 28  slightly to either the right or to the left. The minor diameter of an internal thread (e.g., thread  902  in  FIG. 28 ) may be decreased to provide a tipped thread by, for example, rounding or angling the top of the thread to extend into the interior of the nut past the distance D min  specified in the standard and/or by extending the thread farther into the interior of the nut (while keeping a flat profile at the peak of the thread). The major diameter of an internal thread (e.g., thread  902  in  FIG. 28 ) may be decreased to provide a tipped thread by, for example, filling in the valley of the thread (either uniformly or not) so that the distance D max  is less than the value specified in the UTS standard. By changing the thread angle and/or major or minor diameter of the threads, the interface between the threading on the nut  200  and the threads on a UTS-compliant mating female coaxial connector port (e.g., port  40  of  FIG. 6 ) can be slightly mismatched, thereby increasing the force required to thread the nut  200  onto the mating female coaxial connector port  40  and to unthread the nut  200  from such a mating female coaxial connector port  40 . As will be discussed in more detail below, pursuant to embodiments of the present invention coaxial connectors are provided that have rotatable nuts that include both a first set of threads that has UTS standard compliant threads and a second set of threads that has threads that are not compliant with the UTS standard that provide increased drag or resistance. 
         [0057]      FIG. 14  is a schematic diagram showing how tipped threads having a thread angle that varies from 90 degrees may be formed. As shown in  FIG. 14 , a cutting tool  250  may be used to cut the threads  212 ,  214  in the internal diameter of the first end  210  of nut  200 . To cut the threads  212 , the longitudinal axis of the cutting tool  250  is maintained parallel to the longitudinal axis of the nut  200  (i.e., at an angle of 90 degrees with respect to a lateral cross-section of the nut  200 ). In contrast, with the tipped threads  214  (not shown in  FIG. 14 ), the longitudinal axis of the cutting tool  250  is rotated to, for example, an angle of 85 degrees with respect to a lateral cross-section of the nut  200  to provide threads having a thread angle that is offset from 90 degrees. It will be appreciated that the cutting tool may be rotated in either direction from 90 degrees (e.g., to an angle of 95 degrees instead of 85 degrees), and that the greater the offset from 90 degrees, the higher the degree of increase in the drag and mechanical resistance. In some embodiments, the thread angle of the threads  214  are offset from 90 degrees by between 0.5 and 2.5 degrees. It will be appreciated that tipped threads may be formed in other ways than shown in  FIG. 14 . 
         [0058]      FIG. 15  is an enlarged cross-sectional view of a small portion of a nut  200 ′ in which the tipped threads comprise tipped threads  214 ′ that have a minimum diameter that is less than the specified minimum diameter value D min  set forth in the UTS standards (i.e., the peaks of the threads  214 ′ extend further into the interior of the nut than do the peaks of the UTS-compliant threads  212 ° that are provided in a different part of the nut  200 ′). The nut  200 ′ can have an external appearance that is essentially identical to the external appearance of nut  200  (see  FIG. 12 ), and hence a full drawing of the nut  200 ′ is not provided. As shown in  FIG. 15 , the peaks of the threads  214 ′ extend about 5% further into the interior of the nut  200 ′ than do the peaks of the normal threads  212 ′; the valleys of the threads  214 ′ extend the same distance into the interior of the nut  200 ′ as do the valleys of the UTS-compliant threads  212 ′ (i.e., the major diameter of each of the threads  214 ′ is UTS-compliant). 
         [0059]    When the nut  200  or the nut  200 ′ is mated with the female coaxial connector port  40 , the UTS-compliant threads  212  are designed to mate with the external threads  42  on the port  40 . However, as the nut  200  or  200 ′ is further tightened onto the port  40 , the leading threads  42  of the port  40  contact the tipped threads  214  or  214 °. Because these tipped threads  214 ,  214 ′ either have a thread angle that is offset from 90 degrees or have non-compliant major or minor thread diameters, the external threads  42  on port  40  will not mate perfectly with the threads  214 ,  214 ′, thereby providing increased drag and mechanical resistance. 
         [0060]      FIG. 16  is a perspective view of a nut  300  for an F-style coaxial connector according to further embodiments of the present invention. The nut  300  includes several pipe threads that provide increased drag and mechanical resistance.  FIG. 17  is a cross-sectional view of the nut  300 . The nut  300  could be used, for example, as the nut  170  in the connector  100  of  FIGS. 7-11 . As shown in  FIG. 16 , the nut  300  includes a relatively narrow first end  310  and a relatively wider second end  320  that has a hexagonal-shaped exterior that may receive the end of a wrench. As shown in  FIG. 17 , the internal surface of the nut  300  has a first set of threads  312  that extend throughout the first end  310  of the nut and part way through the second end  320  of the nut  300 . The internal surface of the second end  320  of the nut  300  also includes a second set of threads  314 . The first set of threads  312  may be standard threads, while the second set of threads  314  may be pipe threads. In the depicted embodiment, the pipe threads  314  are the last four threads at the bottom of the end  320 . The pipe threads may be non-UTS standard compliant threads. 
         [0061]    As is known to those of skill in the art, pipe threads are tapered threads that are used to join pipes and other fittings. In some embodiments, pipe threads may have a larger leading edge and/or a much sharper crown. When a torque is applied to pipe threads, the flanks of the tapered threads compress against each other and displace a small amount of material to form a seal, in contrast to parallel/straight threads which hold two pieces together without forming such a seal.  FIG. 18  is an enlarged cross-sectional view of a small portion of the pipe threads  314  of the nut  300  of  FIGS. 16-17  after the nut  300  has been mated with a female coaxial connector port  40 . As shown in  FIG. 18 , when the nut  300  is screwed onto the female coaxial connector port  40 , the tops of the peaks of the pipe threads  314  are displaced, as are the peaks of the mating threads on the female coaxial connector port  40 . The displacement of this material may form a sealed area, and may also provide additional drag and mechanical resistance that resists any forces that would otherwise tend to loosen the connection. 
         [0062]    Pursuant to still further embodiments of the present invention, nuts for F-style coaxial connectors are provided that include bushings such as a nylon or plastic bushing within their internally threaded section. FIG,  19  is a partially cutaway side view of one such nut  400 .  FIG. 20  is a side cross-sectional view of an F-style coaxial connector that includes a nut  450  that has a small bushing that is disposed within the internal threads of the nut. 
         [0063]    As shown in  FIG. 19 , the nut  400  includes a relatively narrow first end  410  and a relatively wider second end  420  that has a hexagonal-shaped exterior that may receive the end of a wrench. The internal surface of the first end  410  is internally threaded with a first set of threads  412  and part of the internal surface of the second end  420  is internally threaded with a second set of threads  414 . The first set of threads  412  and the second set of threads  414  are spaced apart, and a bushing  416  such as, for example, a nylon or plastic bushing, is disposed between the first and second sets of threads  412 ,  414 . Typically, the bushing  416  will not be threaded at the time it is manufactured, although threads are cut into the bushing when the nut  400  is screwed onto a female coaxial cable port such as port  40  of  FIG. 6 . When the nut  400  is mated with the female coaxial cable port  40 , a small amount of the bushing material is displaced, and this displaced material forms a seal that tends to resist further rotation of the nut  400  (in either direction). 
         [0064]    As shown in  FIG. 20 , the nut  450  likewise includes a relatively narrow first end  460  and a relatively wider second end  470  that has a hexagonal-shaped exterior that may receive the end of a wrench. The internal surface of the first end  460  and part of the internal surface of the second end  470  are internally threaded with a set of threads  462 . A small section of the threads  462  is replaced with a bushing  466  such as, for example, a nylon or plastic bushing. Typically, the bushing  466  will not be threaded at the time it is manufactured, although threads are cut into the bushing  466  when the nut  450  is screwed onto a female coaxial cable port such as port  40  of  FIG. 6 . When the nut  450  is mated with such a female coaxial cable port  40 , a small amount of the bushing material is displaced, and this displaced material forms a seal that tends to resist further rotation of the nut  450  (in either direction). 
         [0065]    In some embodiments (such as the nut  400  of  FIG. 19 ), the bushing may be an annular bushing  416  that circumscribes the interior diameter of the nut  400 . As shown in  FIG. 20 , in other embodiments, the bushing (e.g., bushing  466 ) may only circumscribe a portion of the interior diameter of the nut. Typically, the bushing will be sized to replace all or part of  2 - 4  threads of the nut, although other sized bushings may also be used. Typically, threads will be provided on both sides of the bushing along the longitudinal axis of the nut, although in some embodiments, the bushing may replace all or part of the last threads of the nut such that threads are only provided on one side of the bushing. 
         [0066]    As shown in  FIG. 6 , the distal end  44  of a female coaxial cable port  40  that is received within an F-style coaxial connector has a flat surface that mates with the flat bottom surface of the inner contact post of the connector, which acts as a ground plane. Thus, in order to obtain a good ground connection between the female coaxial cable port  40  and an F-style coaxial connector, the nut on the F-style coaxial connector must be fully screwed onto the female coaxial cable port  40 . Typically, the female coaxial connector port  40  is not fully threaded to its distal end  44 . Consequently, in some embodiments of the present invention, the nuts  400 ,  450  are designed so that their respective bushings  416 ,  466  will be offset by a small distance from the bottom surface of the inner contact post when an F-style coaxial connector that includes the nut  400  or  450  is threaded onto the female coaxial cable port  40 . As a result, when a user threads the F-style coaxial connector onto a mating female coaxial connector port  40 , the user only encounters the increased resistance caused by the bushing  416  or  466  at about the same point that the distal end  44  of the mating female coaxial connector port  40  comes into contact with the ground plane. Thus, by positioning the bushing  416  or  466  in this location, it is possible to increase the probability that a good ground connection is obtained. 
         [0067]      FIG. 21  is a perspective view of a nut  500  for an F-style coaxial connector according to further embodiments of the present invention. The nut  500  has an internal diameter that is cut with a slight chamfer to provide increased drag and mechanical resistance when threading the nut  500  onto or off of a mating female coaxial connector port  40 .  FIG. 22  is a cross-sectional view of the nut  500  that illustrates the slight chamfer  530  in the internal diameter of the nut. As shown in  FIG. 22 , the nut  500  includes a relatively narrow first end  510  and a relatively wider second end  520  that has a hexagonal-shaped exterior that may receive the end of a wrench. The internal surface of the first end  510  and part of the internal diameter of the second end  520  are internally threaded with threads  512 . As can be seen in  FIG. 22 , the internal diameter of the nut is cut with a slight chamfer  530  so that the internal diameter decreases with increasing penetration into the nut  500 . 
         [0068]    While the nut  500  includes a chamfer of about two percent (i.e., the internal diameter varies by a total of two percent over the chamfered portion of the nut), in other embodiments the chamfer can be from, for example, about one percent to about three percent. The internal diameter of the nut  500  is designed so that the threads  42  on the distal end  44  of a mating female coaxial connector port  40  will start to cut the inner most threads  512  of the nut  500  when the nut  500  is threaded onto the mating female coaxial connector port  40 . As the threads  512  are cut, material is displaced and hence the chamfer  530  helps resist easy rotation once the nut  500  is mated with the female coaxial connector port  40 . While in  FIG. 22  the chamfer  530  is applied over the entire threaded section of the nut  500 , it will be appreciated that, in other embodiments, the chamfer  530  may be applied only over a portion of the threaded section of the nut  500 . 
         [0069]      FIG. 23  is a perspective view of a nut  600  for an F-style coaxial connector according to still further embodiments of the present invention.  FIG. 24  is a cross-sectional view of the nut  600  of  FIG. 23  taken along the line  24 - 24  in  FIG. 23 . As shown in  FIG. 23 , the exterior of the nut  600  is very similar to the nut  500  depicted in  FIG. 21 . However, the nut  600  is a “dimpled” nut in that during manufacture the external surface of the nut  600  is impacted one or more times with a hard object to form one or more respective dimples  605  in the exterior surface of the nut  600 . These dimples  605  may be positioned directly opposite some of the bottom few threads  612  of the nut  600 . The external force that creates each dimple  605  drives some of the material of the nut  600  inward, creating a defect  625  in the threads  612  opposite the dimple  605 . This defect  625  provides increased drag and mechanical resistance when threading the nut  600  onto or off of a mating female coaxial connector port  40 . 
         [0070]    The nuts according to embodiments of the present invention may be formed using a variety of materials. Typically, however, the nuts will be formed of bronze or of a material that includes bronze. As is known to those of skill in the art, bronze is a relatively soft metal, and hence the bronze may be deformed, cut or the like when the nuts according to embodiments of the present invention are threaded onto female coaxial connector ports made of a harder metal such as steel. This cutting or deformation of the metal may help facilitate providing the increased drag and/or mechanical resistance provided by nuts according to embodiments of the present invention. 
         [0071]    It will be appreciated that the internally threaded nuts according to embodiments of the present invention, such as nuts  200 ,  200 ′,  300 ,  400 ,  450 ,  500  and  600  discussed above, may be used on any F-style coaxial connector, and that the invention is not limited to the particular F-style coaxial connector depicted in  FIGS. 7-11 . By way of example,  FIG. 25  illustrates a compression style back-fitting coaxial “F” connector  730  that has a compression sleeve  750  that fits over the outside surface of the connector body  740 . The compression sleeve  750  includes an annular internal element  752  that is designed to fit between the contact post  760  and the inside surface of the connector body  740  when the compression sleeve is inserted axially into its seated position within the connector body  740  so as to directly engage the shielding wires and/or jacket of a cable and lock the cable in place within the connector. The nut  770  on connector  730  may be any of the nuts according to embodiments of the present invention. Likewise,  FIGS. 26-27  illustrate yet another F-style coaxial connector  830  which may include any of the nuts according to embodiments of the present invention that are described above. The connector  830  once again includes a tubular connector body  840 , a compression sleeve  850 , an inner contact post  860  and an internally threaded nut  870 . The connector  830  further includes a reinforcing shield  844  that fits over a portion of the connector body  840 . The compression sleeve  850  again fits over the outside diameter of the connector body  840 . A compression tool is used to force the compression sleeve  850  over the connector body  840 , and in the process the connector body  840  deforms inwardly to assert a compression/retention force on the jacket and electrical shielding wires/tape of a coaxial cable that is inserted into and over the inner contact post  860 . 
         [0072]    As discussed above with respect to  FIGS. 19 and 20 , the nuts  400 ,  450  may be designed so that their respective bushings  416 ,  466  are offset by a small distance from the bottom surface of the inner contact post when an F-style coaxial connector that includes the nut  400  or  450  is threaded onto the female coaxial cable port  40  so that the increased resistance that is provided by these bushings  416 ,  466  only starts to occur at about the same point that the distal end  44  of a mating female coaxial connector port  40  comes into contact with the ground plane of the nut. It will be appreciated that the location of the tipped threads  214 ,  214 ′ of nuts  200 ,  200 ′, respectively, the location of the pipe threads  314  of nut  300 , the location of the threads having a decreased internal diameter of nut  500  and/or the location of the dimple  625  in the threads of nut  600  may likewise be positioned so that the increased resistance that is provided by these features only starts to occur at about the same point that the distal end  44  of a mating female coaxial connector port  40  comes into contact with the ground plane of the nut. 
         [0073]    It will be appreciated that many modifications may be made to the exemplary embodiments of the present invention described above without departing from the scope of the present invention. 
         [0074]    In the drawings and specification, there have been disclosed typical embodiments of the invention and, although specific terms are employed, they are used in a generic and descriptive sense only and not for purposes of limitation, the scope of the invention being set forth in the following claims.