Abstract:
A coaxial cable connector is provided with a generally tubular mandrel. An attachment element and a retainer are associated with the mandrel and a bushing is telescopically mounted on the retainer. The bushing is adapted for axial movement along the retainer to a closed position wherein the bushing biases a first portion of the retainer into sealing engagement with a seating surface on the exterior of the mandrel. The retainer is sufficiently translucent to permit visual observation of a cable inserted into the retainer.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application claims the benefit of U.S. Provisional Application Ser. No. 61/104,797, filed Oct. 13, 2008, the disclosure of which is incorporated by reference herein. 
    
    
     BACKGROUND OF THE INVENTION 
     The present invention relates to connectors used to attach coaxial cable to a mating port. Coaxial cable is widely used for the transmission of data. A common application is the transmission of television signals from a provider or source to an end user. A typical RG-6 or RG-59 coaxial cable comprises a central conductor surrounded by a dielectric insulator or core, which in turn is surrounded by a conductive shield. The shield is surrounded by a flexible, outer insulative jacket. The conductive shield may include one or more layers of a metallic foil and/or a braided metallic sleeve. 
     A free end of the coaxial cable is secured to a plug or port of a receiving unit by a coaxial cable connector. Releasable engagement elements are formed on the port and connector. In one typical arrangement the port has external threads that are engageable with internal threads on a nut of the connector. Other connectors use a bayonet type connection to the port. Different types of coaxial cable connectors are available and may be categorized by the manner in which they are secured to the cable. Screw-on type connectors are provided with an inner thread that cuts into the outer jacket of the cable when the connector is screwed onto the end of the cable. While such connectors are easily applied to a cable, many believe that they do not result in optimal signal transmission. 
     Radial crimp-type connectors include a metallic tubular portion that is placed over the end of the cable and subjected to a radial compression that deforms the tubular portion and causes it to grip the cable securely. Such a connector and an associated crimp tool are described in U.S. Pat. No. 5,138,864. A perceived inability of such connectors to provide a water-tight seal between the connector and cable has led to a decreased use of radial crimp-type connectors. 
     Axial compression-type connectors employ relative axial movement of two or more elements of the connector to secure the cable within the connector. Typically, such axial movement imparts a radial force that causes a portion of the connector to deform inwardly and grip the cable. For example, U.S. Pat. No. 6,089,913, which is hereby incorporated herein by reference, describes a coaxial cable connector with a crimping ring having a tapered inner surface. The crimping ring surrounds a thin metal sleeve that is coaxial with and spaced from an inner sleeve to form a jacket-receiving gap. The free end of a coaxial cable is pressed into the connector, typically with the central conductor, dielectric and foil layer entering the inner sleeve and the jacket and braided layer of the cable separating from the underlying dielectric insulator to occupy the jacket-receiving cavity between the inner and outer sleeves of the connector. With the cable so inserted in the connector, the crimping ring is advanced axially along the outer sleeve, which eventually causes the tapered inner surface of the crimping ring to bear against the outer sleeve. As the crimping ring continues to slide along the outer sleeve, it deforms the thin metal sleeve inwardly, thereby decreasing the gap between the sleeves of the connector and pinning the jacket and braided layer between the sleeves. 
     Another axial compression type connector is shown in U.S. Pat. No. 6,261,126, the disclosure of which is hereby incorporated herein by reference. In this connector the outer sleeve is not deformed during axial compression of a bushing. Instead, the bushing has a trailing end that has a reduced internal diameter that impinges on the cable jacket and pinches it between the bushing and the inner sleeve. A similar axial compression type connector is shown in U.S. Pat. No. 6,848,939, the disclosure of which is hereby incorporated herein by reference. It has an inner collar inside a bushing for engaging the jacket. 
     Regardless of the type of connector employed, a secure fit between the connector and the cable is important. An improperly fit connector-cable pair can become disengaged or provide an incomplete seal, which risks allowing moisture into the connector, thereby degrading the performance of the cable. Furthermore, the initial seating of the cable in the connector is important to assure a secure connection. Although tools are available for the purpose, the initial seating is typically done manually with the technician simply holding the connector in one hand and pressing the prepared cable end into the connector with the other hand. To make a proper connection the cable must advance fully into the connector but in some types of connectors the technician cannot see the interior of the connector to know where the cable is in relation to the connector. 
     It is also important that the connector seals against moisture entering the connector. While many connectors are installed indoors where moisture is not expected to be an issue, some will be installed in locations where moisture will definitely be a concern. Installers do not want to maintain inventories of “indoor” and “outdoor” connectors so one connector type must be suitable for both applications. In the past O-rings have been widely used to provide the necessary seals. While O-rings are generally effective, they do add cost and complexity to the connector. In some designs more than one O-ring is required to seal all the possible leakage paths. Press fitting parts of the connector together can also provide moisture seals but doing so adds to the complexity of the connector assembly process and the equipment needed in the factory. 
     SUMMARY OF THE INVENTION 
     There are several aspects of the present subject matter which may be embodied in the devices and systems described and claimed below. These aspects may be employed alone or in combination with other aspects of the subject matter described herein. 
     A coaxial cable connector has a generally tubular mandrel. The mandrel has a wall that defines an interior cylindrical bore. The cylindrical bore is sized for receiving at least the central conductor and dielectric core of a coaxial cable inserted into the connector. A seat surface is formed on the exterior of the wall. At least one locating member, such as a shoulder, is also formed on the exterior of the mandrel wall. 
     A retainer has a first portion in engagement with the locating member to axially fix the location of the retainer on the mandrel. The first portion of the retainer also includes a collar having a counterbore. The counterbore defines an interior surface which is in facing relation with the seat surface of the mandrel. A second portion of the retainer forms a sleeve which is connected to the collar and spaced from the mandrel to define a cavity between the exterior of the mandrel and an internal surface of the sleeve. The cavity is sized for receiving at least a braided sleeve of the shield and the jacket of a coaxial cable inserted into the connector. 
     A bushing is telescopically engageable with the retainer. The bushing slides axially on the retainer from a first, open position to a second, closed position. When the bushing is in the first, open position the bushing is axially spaced from the retainer&#39;s collar and the interior surface of the collar is in non-sealing relation with the seat surface of the mandrel. When the bushing is in the second, closed position, the bushing engages the collar to bias its interior surface into sealing engagement with the seat surface. 
     The connector further includes an attachment element which is non-releasably engageable with the mandrel or the retainer. The attachment element is releasably engageable with the port of a device to which the cable is to be connected. 
     According to another aspect of the present disclosure, a coaxial cable connector is provided with a generally tubular mandrel. An attachment element and a retainer are associated with the mandrel, with a bushing being associated with the retainer. The bushing is adapted for movement along the retainer and the retainer is sufficiently translucent or transparent to permit visual observation of the cable jacket within the retainer. This allows the installer to know when the cable has been properly seated within the connector. 
     In another aspect of the present disclosure, some of the components of the connector may have a lubricant applied thereto to reduce the cable insertion force and make relative movement of the connector components easier. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a side elevation view, with the lower half in cross-section, of a coaxial cable connector of the present invention, with a coaxial cable positioned therein but prior to closing of the bushing. 
         FIG. 2  is a side elevation view of the mandrel with a portion shown in section. 
         FIG. 3  is a side elevation view of the retainer with a portion shown in section. 
         FIG. 4  is a side elevation view of the bushing with a portion shown in section. 
         FIG. 5  is a cross-sectional view of the coaxial cable connector with the bushing in a first, open position. 
         FIG. 6  is a cross-sectional view of the coaxial cable connector with the bushing in a second, closed position. 
         FIG. 7  is a cross-sectional view of the coaxial cable connector with the bushing in a second, closed position and the attachment element in an engaged position. 
         FIG. 8  is an front end elevation view of an alternate embodiment of the present invention, illustrating a BNC-type connector. 
         FIG. 9  is a section taken along line  9 - 9  of  FIG. 8 , showing the connector in an uncompressed state. 
         FIG. 10  is a section similar to  FIG. 9 , showing the connector in a compressed state but with the cable omitted for clarity. 
         FIG. 11  is a section similar to  FIG. 9 , showing an alternate embodiment of an F connector with a different bushing from that of the  FIG. 1-7  F connector. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The embodiments disclosed herein are for the purpose of providing the required description of the present subject matter. These embodiments are only exemplary, and may be embodied in various forms. Therefore, specific details disclosed herein are not to be interpreted as limiting the subject matter as defined in the accompanying claims. 
       FIG. 1  shows a coaxial cable connector  10  suitable for use with a typical coaxial cable. The coaxial cable is shown generally at  12 . Coaxial cable typically has a central conductor  14  at the center of the cable. The central conductor is usually made of copper or a copper-plated material. A cylindrical dielectric core  16  encloses the central conductor. A conductive shield  18  surrounds the dielectric core and an outer, insulative jacket  20  in turn surrounds the shield. The shield  18  is shown diagrammatically as a single layer. It will be understood that, depending on the application requirements, the shield may include a metallic foil layer and/or a braided metal sleeve, or multiple foil layers and braided sleeves. In a common arrangement the shield has a foil layer surrounding the dielectric core and a braided sleeve surrounding the foil layer. The shield layers may be made of aluminum. Preparation of the end of a cable entails stripping an end portion of the outer jacket, folding the braided sleeve back on the jacket, and stripping an end portion of the dielectric core to expose an end of the central conductor. The end of the conductor thus prepared is inserted into the end of the connector as will be described below. 
     Looking at  FIG. 5 , the connector  10  includes a generally tubular mandrel  22 , a retainer  24 , a bushing  26 , and an attachment element  28 . In this embodiment the attachment element  28  is in the form of a nut. When the connector is installed on a port, the interface between the nut and mandrel is sealed by an O-ring  30 . For reference purposes, the connector will be described herein as having a front portion located at the nut, which is the left side as viewed in all of the Figures. The rear of the connector is where the bushing is located, which is the right side in the Figures. 
     Details of the mandrel  22  are shown in  FIG. 2 . The mandrel is preferably made of a conductive material, such as brass. The mandrel has a generally tubular wall  32  that defines an interior cylindrical bore  34 . The bore is sized to receive the central conductor  14 , the dielectric core  16  and, if applicable, the foil layer of the shield of a cable inserted into the connector. The exterior of the wall  32  has several features, including a pair of barbs  36  at the rear end. The barbs  36  are adapted for gripping the inner surface of a cable shield layer. The rear end of the mandrel has a diameter suitable for sliding over the dielectric core  16  and between an inner foil layer and a braided sleeve of the shield  18  of a cable. Moving toward the front end of the mandrel&#39;s exterior surface from the barbs  36 , the wall  32  has a midsection  38  with a small step at  40 . The midsection terminates at a beveled section  42 . The beveled section joins a first locating member in the form of a rib  44 . Extending forwardly from the rib  44  is a seat surface  46 . The seat surface terminates at a second locating member in the form of a shoulder  48 . Together the rib  44  and shoulder  48  form locating members that engage the retainer  24  to fix the axial position of the retainer, as will be described below. The front edge of the shoulder  48  is bounded by an O-ring seat  50 . Forwardly from the O-ring seat there is a stepped portion  52  which in turn joins an end flange  54 . The end flange has the largest outside diameter on the mandrel for purposes of retaining the nut on the mandrel. 
     Details of the retainer  24  are shown in  FIG. 3 . The retainer has a generally cylindrical exterior, with a first portion  56  integrally joined to a second portion  58  at boundary  60 . It will be noted that the outside diameter of the first portion  56  is slightly greater than that of the second portion  58 . The difference in the outside diameters can be approximately 0.004 inches. The exterior of the second portion includes a rib  62  extending radially outwardly. The rear edge of the second portion has slightly reduced outside diameter section  64 . 
     The sectioned portion of  FIG. 3  illustrates the interior of the retainer  24 . Here it can be seen that the first portion  56  has a radially-extending collar  66 . The collar includes a counterbore which defines an interior surface  68  at the inside diameter of the counterbore. There is a notch  70  at the junction of the interior surface  68  with the rear radial face  72  of the collar  66 . There is a chamfer  74  at the junction of the interior surface  68  with the front radial face  76  of the collar  66 . The second portion  58  of the retainer includes an axially-extending sleeve  78 . A bore in the sleeve defines an internal surface  80  of the second portion. The retainer  24  is made of a material that is at least translucent, and preferably substantially transparent. Transparent polycarbonate is an example of a suitable material, although others are possible. As will be described in greater detail below, the retainer is relatively flexible compared to a metal component and it allows for visibility into the interior of the retainer  24  when inserting the free end of a cable. 
     Turning now to  FIG. 4 , details of the bushing  26  will be described. The bushing is made of a substantially rigid material, such as brass. The bushing includes a sleeve  82  with a bore therethrough that defines an interior surface  84 . The inside diameter of the bushing&#39;s sleeve  82  and the outside diameter of the retainer&#39;s sleeve  78  are selected to permit a telescoping engagement of the bushing on the retainer. However, as mentioned above, the outside diameter of the retainer&#39;s collar  66  is somewhat greater than the outside diameter of the retainer&#39;s sleeve  78 . As a result of the relationship between the inner and outer diameters of the bushing and the retainer&#39;s collar, respectively, and the retainer being more flexible than the bushing, sliding engagement of the bushing&#39;s sleeve  82  onto the collar  66  creates interference that causes the bushing to bias the retainer radially toward the mandrel. Continuing with the details of the bushing, a first rib-receiving groove  86  is formed near the front end of the bushing. A similar second rib-receiving groove  88  is located near the midpoint of the bushing. The rear end of the sleeve  82  joins a radially-extending collar  90 . The collar has a counterbore  92  through it. 
     The attachment element in the form of nut  28  is associated with the front end of the mandrel  22 . The nut  28  includes inner threads  94  and may be rotatable with respect to the underlying mandrel  22 . A flange  96  on the nut engages the end flange  54  of the mandrel to permit the nut to rotate relative to the mandrel but the nut cannot move axially off the end of the mandrel. When the nut  28  is threaded onto a mating port, the inside diameter of the flange  96  will press the O-ring  30  against the O-ring seat  50  of the mandrel  22 , thereby providing a moisture resistant seal between the nut and mandrel. 
     Assembly of the connector is as follows. First the O-ring  30  is slipped over the mandrel and into the O-ring seat  50 . Then the nut  28  is placed over the rear end of the mandrel  22  and advanced forwardly until the nut&#39;s flange  96  is opposite the mandrel&#39;s shoulder  48 , as seen in  FIGS. 1 ,  5  and  6 . Next the retainer  24  is placed on the mandrel  22  by sliding the collar  66  over the rear end of the mandrel and advancing the retainer toward the front of the mandrel. When the chamfer  74  engages the beveled section  42 , the beveled section centers the retainer on the mandrel. Upon continued advancement of the retainer the rib  44  causes the collar  66  to expand radially to permit the collar to snap fit in between the mandrel&#39;s shoulder  48  and rib  44 . The notch  70  accommodates the rib  44 . The shoulder and rib together serve as locating members to fix the axial position of the retainer on the mandrel. In this position the retainer collar&#39;s internal surface  68  is in facing relation with the seat surface  46  on the mandrel. Also, the internal surface  80  of the retainer&#39;s sleeve  78  is radially spaced from the exterior surface of the mandrel to define a cavity  98  ( FIGS. 5-7 ). The cavity is sized to receive the braided sleeve of the shield  18  and the jacket  20  of a cable inserted into the connector. The final step in the initial assembly is to place the bushing  26  onto the rear portion of the retainer&#39;s sleeve  78 . The bushing is advanced until the retainer&#39;s rib  62  engages the first rib-receiving groove  86 , as seen in  FIG. 5 . This defines a first, open position of the bushing. In this position the connector is ready to receive the prepared end of a coaxial cable. 
     The use, operation and function of the connector are as follows. The free end of a coaxial cable is prepared for insertion into the connector  10  as described above. The prepared end of the cable is then inserted into the rear end of the bushing&#39;s collar  90 . Upon further insertion of the cable the central conductor  14  and dielectric core  16  encounter the rear end of the mandrel. The conductor and core (and foil layer of the shield, if any) enter the bore  34  of the mandrel while the braided sleeve of the shield  18  and the jacket  20  enter the cavity  98  between the mandrel and retainer. Insertion of the cable then continues until the jacket bottoms on the rear radial face  72  of the collar  66 . The non-opaque retainer  24  allows the user to visually confirm that the braided sleeve of the shield  18  and the jacket  20  have been fully inserted into the cavity  98 . If the strip lengths were correctly made, the dielectric core should then be substantially aligned with the front end of the mandrel. 
     When the user has confirmed that the cable is fully inserted into the connector  10 , the bushing  26  is compressed axially along the retainer  24  until the bushing&#39;s collar engages the rear edge of the retainer. This is typically done with the aid of a tool. When the bushing is in the second, closed position the rib  62  is in the second groove  88 . Engagement of the rib  62  in groove  88  holds the bushing in this second, closed position. See  FIG. 6 . As the bushing reaches the second, closed position the collar  90  of the bushing will engage the jacket  20  of the cable. The annular surface of counterbore  92  will pinch the jacket between the collar  90  and the barbs  36  of the mandrel. This prevents retraction of the cable from the connector. 
     Also, when the bushing moves to the second, closed position the front edge of the bushing engages the outside diameter of the retainer&#39;s collar  66 . As explained above, the inside diameter of the bushing&#39;s front end is less than the outside diameter of the collar so that interference is created when these two components engage. Since the bushing is more rigid than the collar  66 , the collar is compressed radially by the forwardly moving bushing. This radial compression causes the interior surface  68  of the collar to engage the seat surface  46  of the mandrel in sealing engagement. Thus, the retainer and mandrel are sealed against entry of moisture into the cavity  98  by the closing motion of the bushing, which creates the biasing force on the retainer that in turn creates the seal. No O-ring or other sealing member is required at the retainer and mandrel interface. This arrangement also has the benefit that initial assembly of the retainer on the mandrel is achieved by a simple snap fit of the collar into the locating members but a tight, sealing contact is not necessary during initial assembly. Sealing contact is achieved during installation of the connector onto a cable. 
       FIG. 7  schematically illustrates the condition of the connector  10  after it is attached to a plug or port of a mating device. When the nut  28  is tightened onto the port, the port will engage the front surface of the mandrel&#39;s end flange  54 . Further tightening causes the port to push the mandrel  22  toward the rear, until the rear surface of the end flange engages the flange  96  of the nut. This is what creates the separation between the nut and the retainer as seen in  FIG. 7 . The rearward movement of the mandrel also carries the O-ring  30  into alignment with the inside diameter of the nut&#39;s flange  96 , thereby sealing this annular surface. 
     As mentioned above, the non-opaque retainer is beneficial in the F-type connector shown in  FIGS. 1-7  in that it permits visual indication of complete entry of the cable jacket into the cavity  98 . An F connector provides an alternate indicator of full entry of the cable into the connector. The interior of the nut  28  and the front of the mandrel  22  provide an unobstructed view of the ends of the central conductor  14  and the dielectric core  16  as they approach the front end of the connector. Accordingly, as is evident in  FIG. 1 , it is possible to see when the core  16  reaches the front end of the mandrel, at which point the cable is fully seated on the connector. This alternate indicator of full entry is not available in BNC type connectors. The front end of a BNC connector has a hollow pin on the connector&#39;s axis. The pin is supported in a mounting block and receives the central conductor therein. An example of a BNC connector is shown in FIGS. 11 and 11A of U.S. Pat. No. 7,029,326, the disclosure of which is hereby incorporated herein by reference. The pin and its mounting block completely obscure any view at all of the cable from the front of the connector. In a conventional blind BNC connector, i.e., one without a non-opaque retainer, the user can confirm that the cable has been fully inserted into the connector by one of the following, none of which are entirely satisfactory: a tactile indication (i.e., the feel of the jacket abutting a stop surface); a cessation of further movement of the cable into the connector; or placing the connector adjacent to the end of the cable with the center conductor approximately even with the front end of the connector, noting or marking the location on the cable where the rear end of the connector lies and then inserting the cable until the marked location of the cable is even with the rear end of the cable. If the cable snags on a portion of connector, then the user may incorrectly surmise that the cable is fully inserted. There is no way in the standard BNC connector to visually confirm full insertion. Hence, the non-opaque retainer according to the present disclosure is even more important in a BNC connector because it provides the only visual confirmation or indication in a BNC connector that the cable is fully inserted. Full insertion preferably should be confirmed before proceeding with securing the connector to the cable. The present invention&#39;s non-opaque retainer permits this in a manner that is not possible with the prior art connectors. 
       FIGS. 8-10  illustrate a BNC type connector according to the present disclosure. This embodiment has several components that are similar to those of  FIGS. 1-7  and these will be given the same reference numerals with the addition of a letter A. Connector  10 A includes a mandrel  22 A, a non-opaque retainer  24 A and a bushing  26 A. Attachment element  28 A is in the form of a bayonet-type head. 
     Looking at details of the mandrel  22 A, as in the previous embodiment it has a generally tubular wall  32 A that defines an interior cylindrical bore  34 A with a single barb  36 A at the rear end. The wall  32 A terminates at a beveled section  42 A which joins a first locating member in the form of a rib  44 A. Extending forwardly from the rib  44 A is a seat surface  46 A. The seat surface terminates at a second locating member in the form of a shoulder  48 A. Together the rib  44 A and shoulder  48 A form locating members that engage the retainer  24 A to fix the axial position of the retainer, as in the first embodiment. 
     The retainer  24 A has a generally cylindrical exterior, with a first portion  56 A integrally joined to a second portion  58 A. It will be noted that the outside diameter of the first portion  56 A is slightly greater than that of the second portion  58 A. The difference in the outside diameters can be approximately 0.004 inches. The exterior of the second portion includes a rib  62 A extending radially outwardly. 
     The interior of the retainer  24 A has a radially-extending collar  66 A. The collar includes a counterbore which defines an interior surface  68 A at the inside diameter of the counterbore. There is a notch at the junction of the interior surface  68 A with the rear radial face  72 A of the collar  66 A. There is a chamfer at the junction of the interior surface  68 A with the front radial face of the collar  66 A. The retainer has a sleeve  78 A and a bore in the sleeve defines an internal surface  80 A of the second portion  58 A. The retainer  24 A is made of a material that is at least translucent, and preferably substantially transparent. Transparent polycarbonate is an example of a suitable material, although others are possible. As described above, the retainer is relatively flexible compared to a metal component and it allows for visibility into the interior of the retainer  24 A when inserting the free end of a cable. This is especially useful in the BNC type connector. 
     Turning now to details of the bushing  26 A, as in the previous embodiment it is made of a substantially rigid material, such as brass. The bushing includes a sleeve  82 A with a bore therethrough that defines an interior surface  84 A. The inside diameter of the bushing&#39;s sleeve  82 A and the outside diameter of the retainer&#39;s sleeve  78 A are selected to permit a telescoping engagement of the bushing on the retainer. However, as mentioned above, the outside diameter of the retainer&#39;s collar  66 A is somewhat greater than the outside diameter of the retainer&#39;s sleeve  78 A. As a result of the relationship between the inner and outer diameters of the bushing and the retainer&#39;s collar, respectively, and the retainer being more flexible than the bushing, sliding engagement of the bushing&#39;s sleeve  82 A onto the collar  66 A creates interference that causes the bushing to bias the retainer radially toward the mandrel  22 A. 
     Continuing with the details of the bushing, a rib-receiving groove  86 A is formed near the front end of the bushing. The rear end of the sleeve  82 A joins a radially-extending collar  90 A which has a counterbore  92 A through it. The collar  90 A retains a back seal  100  inside the bushing. When the bushing is moved to the compressed state of  FIG. 10  the back seal  100  engages the outer jacket of a cable and pinches it between the back seal and the mandrel to retain the connector on the cable. 
     The front portion of the BNC connector  10 A has several components that have no counterpart in the F connector  10 . These include the collar contact  102 . The collar contact is a generally cylindrical member having an external flange  104  and an internal flange  106 . The rear end of the collar contact is press fit over the shoulder  48 A of the mandrel  22 A. A plurality of axial slots  108  at the front end of the collar contact  102  define spring-like fingers for engagement with a port. The internal flange  106  traps a dielectric mounting block  110  between it and the front surface of shoulder  48 A. The mounting block is press fit into the collar contact just behind the flange  106 . The mounting block has a central bore therethrough which flares outwardly at the rear end. The front end of the bore mounts a pin  112  which has a hollow rear portion into which a center conductor contact  114  fits. The flared bore and contact  114  receive the central conductor of a cable therethrough. The central conductor ends up in the hollow portion of the pin  112  if the cable is fully seated in the connector. But as evident in  FIGS. 9 and 10 , the user cannot look in the front end of the head  28 A and see where the cable is because the cable is completely obscured from view by the pin  112 , mounting block  110  and internal flange  106 . This is why the non-opaque retainer provides such an advantage in this construction, because it allows the user to see whether the outer insulative jacket of the cable is properly seated against the rear radial face  72 A of the retainer. 
     The front portion of the connector is completed by a front and rear washers  116 ,  118 . the front washer bears against the external flange  104  and engages a shoulder of the head  28 A. Rear washer fits into a notch inside the trailing edge of the head  28 A. A spring  120  resides between the washers to bias the head  28 A rearwardly. 
     The use, operation and function of the connector of  FIGS. 8-10  is similar that of the connector of  FIGS. 1-7 . The prepared end of the cable is inserted into the bushing and pushed forwardly until cable the central conductor  14  fits into the pin  112 . At this point the outer jacket bottoms on the rear radial face  72 A of the collar  66 A. The non-opaque retainer  24 A allows the user to visually confirm that the braided sleeve of the shield  18  and the jacket  20  have been fully inserted into the cavity between the retainer and the mandrel. When the user has confirmed that the cable is fully inserted into the connector  10 A, the bushing  26 A is compressed axially along the retainer  24 A until the position of  FIG. 10  is reached. This is typically done with the aid of a tool. As the bushing reaches the second, closed position the back seal  100  of the bushing will engage the jacket  20  of the cable and pinch the jacket between the bushing and the barb  36  of the mandrel. This prevents retraction of the cable from the connector. 
     Also, when the bushing moves to the second, closed position the front edge of the bushing engages the outside diameter of the retainer&#39;s collar  66 A. As explained above, the inside diameter of the bushing&#39;s front end is less than the outside diameter of the collar so that interference is created when these two components engage. Since the bushing is more rigid than the collar  66 A, the collar is compressed radially by the forwardly moving bushing. This radial compression causes the interior surface  68 A of the collar to engage the seat surface  46 A of the mandrel in sealing engagement. Thus, the retainer and mandrel are sealed against entry of moisture into the cavity by the closing motion of the bushing, which creates the biasing force on the retainer that in turn creates the seal. 
     In a preferred embodiment at least the surfaces involved in the sliding contact between the retainer and bushing are lubricated by a dry film lubricant, such as a synthetic wax emulsion. The lubricant reduces the friction of the bushing on the retainer. This makes it easier to get quad cables to enter the connector and makes the bushing slide more easily. The mandrel may also be similarly lubricated. The presence of lubricant reduces the cable insertion force significantly. This allows the connector to accept a wider range of cable sizes and types, which is one of the factors which combines with other features to make the connector more universal. 
       FIG. 11  illustrates an alternate form of an F connector according to the present disclosure. This embodiment has several components that are similar to those of  FIGS. 1-7  and these will be given the same reference numerals with the addition of a letter B. Connector  10 B includes a mandrel  22 B, a non-opaque retainer  24 B and a bushing  26 B. Attachment element  28 B is in the form of a nut. These components generally have a similar structure and operate similarly to those of the  FIG. 7  embodiment with the exception of the rear end of the bushing  26 B. The rear end of bushing  26 B has a similar structure and operates similarly to that of the  FIG. 8-10  embodiment. That is, bushing  26 B has a sleeve  82 B which joins a radially-extending collar  90 B which has a counterbore  92 B through it. The collar  90 B retains a back seal  100 B inside the bushing. When the bushing is moved to the compressed state the back seal  100 B engages the outer jacket of a cable and pinches it between the back seal and the mandrel to retain the connector on the cable. 
     While this invention has been described with reference to certain illustrative aspects, it will be understood that this description shall not be construed in a limiting sense. Rather, various changes and modifications can be made to the illustrative embodiments without departing from the true spirit and scope of the invention, as defined by the following claims. Furthermore, it will be appreciated that any such changes and modifications will be recognized by those skilled in the art as an equivalent to one or more elements of the following claims, and shall be covered by such claims to the fullest extent permitted by law. For example, while two locating members are shown to fix the axial position of the retainer, one on either side of the retainer&#39;s collar, this arrangement could be otherwise. A single rib and groove could be used to hold the retainer in place. Also, alternatives to the bushing&#39;s collar are possible for retaining the connector on the cable. For example, the crimping ring of U.S. Pat. No. 6,089,913 could be used. Or the inner collar arrangement of U.S. Pat. No. 6,848,939 could be used. Also, while the shield is most commonly intended to reside outside of the mandrel when the cable is installed, it will be understood that other arrangements with respect to the shield are possible. In particular, since the shield could include multiple foil layers and/or multiple braid layers, inner ones of these layers may go inside the mandrel while outer layers may end up outside the mandrel.