Abstract:
A testing device provides pin height, continuity, and concentricity testing for coaxial connectors and cables. The testing device provides connector jacks with support shafts that properly align and stabilize the connectors during testing. Circuitry is provided to indicate if the pin height is sufficient, if the cable is an open circuit, a short circuit, or has an adequate continuity, and if the center pin of the connector is sufficiently concentric with the outer sleeve. The jacks may have an outer surface with slots providing a slip fit configuration that allows the coaxial connector to be easily inserted and removed.

Description:
TECHNICAL FIELD 
     The present invention is directed to coaxial connector and cable testing, and more specifically to a device for testing continuity, concentricity, and/or pin height of coaxial connectors and cables. 
     BACKGROUND 
     Cables with coaxial connectors are prevalently used for electrical signal transfer. Various types of coaxial connectors are available, such as BNC connectors and miniature coaxial connectors. The coaxial connector has a sleeve portion that is typically connected to the signal ground conductor of the cable, and the connector has a center pin that is the termination of the cable&#39;s signal conductor. The center pin is positioned concentrically within the sleeve and conducts the signal from the source to the destination. 
     The coaxial cable&#39;s ability to carry the signal from the source to the destination is dependent upon the cable&#39;s qualities and those of the coaxial connectors at each end. The cable must have sufficient signal continuity through the electrical signal conductor to its ends and through the signal ground conductor to the sleeves. Thus, short circuits or open circuits within the cable and connector are prohibited. Additionally, continuity between a connector and jack must be established by the coaxial connector&#39;s interface to the jack. This interface requires that the coaxial connector have center pin concentricity such that the center pin properly enters a connector jack receptacle that conducts the signal received from the center pin when the sleeve engages a receiving sleeve of the jack. Furthermore, the center pin must extend far enough (i.e., have a sufficient pin height) relative to the sleeve position to engage the receptacle of the connector to establish signal continuity between the connector and the jack. 
     When installing coaxial cables, it is difficult to verify that the cable and connector meet requirements such as those mentioned above. Care must be exercised in verifying continuity, concentricity, and pin height to avoid further damage to the connector. This is especially true for miniature coaxial connectors where the center pin is more vulnerable. 
     Thus, there is a need for a device that permits continuity, concentricity, and pin height to be easily tested for a coaxial connector and cable without risking damage to the connector. 
     SUMMARY 
     The present invention provides a device that may easily test one or more of the qualities of a coaxial cable and connector without harming the coaxial connector. Embodiments of the present invention provide features that test continuity, pin height, and/or concentricity while providing support for the coaxial connector to prevent damage to the center pin. 
     The present invention may be viewed as a device for testing a cable having a coaxial connector with a sleeve and a center pin. The device includes a housing having opposing surfaces forming a housing interior with the housing having at least a first and second aperture. A first coaxial connector jack is disposed on one of the surfaces and passes through the first aperture. The first coaxial connector jack has a first center pin receptacle surrounded by a first support shaft that is sized to concentrically receive an inner side of the sleeve of the coaxial connector. The first coaxial connector jack also has a reference electrode. 
     A second coaxial connector jack is disposed on one of the surfaces and passes through the second aperture. The second coaxial connector jack has a second center pin receptacle surrounded by a second support shaft that is sized to concentrically receive the inner side of the sleeve. First circuitry is disposed within the housing and electrically connected to the first center pin receptacle and the reference electrode. The first circuitry provides electrical power to the coaxial connector received by the first coaxial connector jack to determine whether the electrical resistance of the coaxial connector is within a predetermined range and to provide a first external indication of the determination. 
     A first switch is in operable connection with the second center pin receptacle, and the switch is repositioned in response to the second center pin receptacle receiving the center pin of the coaxial connector that has a length greater than a threshold. Second circuitry is disposed within the housing and is electrically connected to the first switch, with the second circuitry providing a second external indication in response to the first switch being repositioned. 
     The present invention may be viewed as another device for testing a cable having a coaxial connector with a sleeve and center pin. The device includes a housing having opposing surfaces forming a housing interior, and the housing has at least a first aperture. A first coaxial connector jack is disposed on one of the surfaces and passes through the first aperture and has a first center pin receptacle surrounded by a first support shaft that is sized to concentrically receive an inner side of the sleeve of the coaxial connector. The first coaxial connector has a reference electrode, and first circuitry is disposed within the housing and electrically connected to the first center pin receptacle and the reference electrode. The first circuitry provides electrical power to the coaxial connector received by the first coaxial connector jack to determine whether the electrical resistance of the coaxial connector is within a predetermined range and to provide an external indication of the determination. 
     The present invention may be viewed as another device for testing a cable having a coaxial connector with a sleeve and a center pin. The device includes a housing having opposing surfaces forming a housing interior, and the housing has at least a first aperture. A first coaxial connector jack is disposed on one of the surfaces and passes through the first aperture, and the first coaxial connector jack has a first center pin receptacle surrounded by a first support shaft that is sized to concentrically receive an inner side of the sleeve of the coaxial connector. A first switch in operable connection with the first center pin receptacle is repositioned in response to the first center pin receptacle receiving a center pin of the coaxial connector that has a length greater than a threshold. First circuitry is disposed within the housing and electrically connected to the first switch and provides an external indication in response to the first switch being repositioned. 
     The present invention may be viewed as another device for testing a cable having a coaxial connector with a sleeve and a center pin. The device includes a coaxial connector jack that includes a first support shaft having a first pin entryway of a first diameter at a receiving end of the support shaft with the support shaft being sized to receive an inner side of the sleeve. The connector jack also includes a first center pin receptacle that is surrounded by the first support shaft and has an inner diameter at a receiving end of the receptacle greater than or equal to the first diameter. 
     The present invention may be viewed as another device for testing a cable having a coaxial connector with a sleeve and a center pin. The device includes a coaxial connector jack having a first support shaft being sized to receive an inner side of the sleeve. The connector jack also includes a first center pin receptacle surrounded by the first support shaft and a concentric outer support surface surrounding the first support shaft. The outer support surface is sized to concentrically engage an outer side of the sleeve, and the outer support surface has longitudinal slots that accept barbs extending radially from the coaxial connector that limit rotation of the coaxial connector while allowing longitudinal movement of the coaxial connector. 
    
    
     DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a perspective view of one style of coaxial connector for use with an embodiment of the present invention. 
     FIG. 2 is a side elevation view of the miniature coaxial connector of FIG.  1 . 
     FIG. 3 is an exploded perspective view of the coaxial connector of FIG.  1 . 
     FIG. 4 is an assembled cross-sectional view of the coaxial connector of FIG.  1 . 
     FIGS. 5A-5D are top, front, right side, and perspective views, respectively, of an embodiment of the present invention for use with the coaxial connector of FIG.  1 . 
     FIG. 6A is an exploded perspective view of the embodiment of the present invention. 
     FIG. 6B is a partial exploded perspective view of a pin height structure of the embodiment of the present invention. 
     FIG. 6C is a partial exploded view of a connector jack of the embodiment of the present invention for testing pin height and/or concentricity. 
     FIG. 7 is an exploded view of a structure of an embodiment of the present invention for testing continuity and/or concentricity. 
     FIGS. 8A-8D are top, top front perspective, top rear perspective, and cross-sectional views, respectively, of the assembled connector jack structure of FIG.  7 . 
     FIGS. 9A and 9B are perspective and cross-sectional views, respectively, of a support shaft of the connector jack of FIG.  7 . 
     FIGS. 10A-10C are perspective, cross-sectional, and front views, respectively, of an outer support surface of the connector jack of FIG.  7 . 
     FIGS. 11A and B are perspective and cross-sectional views, respectively, of a center pin receptacle support of the connector jack of FIG.  7 . 
     FIGS. 12A-12D are front, top, cross-sectional, and right side views, respectively, of a block fitting of the connector jack of FIG.  6 B. 
     FIG. 13 is a cross-sectional view of the embodiment of the present invention shown in FIG. 5A taken through the connector jack structure for testing pin height and/or concentricity. 
     FIG. 14 is a block diagram of the electrical circuitry involved in testing pin height and continuity. 
    
    
     DETAILED DESCRIPTION 
     Various embodiments of the present invention will be described in detail with reference to the drawings, wherein like reference numerals represent like parts and assemblies through the several views. Reference to various embodiments does not limit the scope of the invention, which is limited only by the scope of the claims attached hereto. 
     FIGS. 1-4 illustrate an exemplary coaxial connector  520  for electrically connecting a coax cable (not shown) to a coax jack and its ordinary connection to a typical connector jack. The connector  520  includes a generally cylindrical outer jacket  522 . A barbed insert  524  is provided and is sized to be received within the interior of jacket  522 . The elements of the connector  520  further include a conductor pin  526 , dielectric spacers  528 , first and second cooperating crimping members  530 ,  532 , and a rear retaining sleeve  534 . A coax cable with a central conductor and ground sleeve is connected to the connector  520 . 
     Shown best in FIGS. 3 and 4, barbed insert  524  is slidably received within outer jacket  522 . The barbed insert has diametrically opposed arcuate and projecting barbs  536 . Projecting outwardly from barbs  536  are protruding and angularly ramped locking tabs  538 . Tabs  538  project through slots  540  formed in a reduced diameter portion  521  of outer jacket  522 . Reduced diameter portion  521  is sized to be received within rear ports formed in a housing body (not shown). 
     The locking tabs  538  are disposed so that they are received within grooves of the housing to retain connector  520  from axial movement relative to the housing while permitting rotational movement. With the connector  520  so received, the center pin  527  of conductor  526  is disposed so that they are received within pin receiving conductors. The insulators  528  retain the pin  526  in concentric spaced relative to the conductive insert  524  and conductive outer jacket  522 . The pin includes a conductor-receiving bore  552  sized to receive a central conductor of a commercially available coax cable. 
     The grounded shield of the coaxial cable is placed between the opposing surfaces of crimping members  530 ,  532  after which outer crimping member  532  may be crimped against inner crimping member  530  to securely connect the grounding shield of the coaxial cable to the conductive outer jacket  520  in insert  524 . The rear retaining sleeve  534  may be connected to the insulated sheeting of the coaxial cable with the rear retaining sleeve  534  connected to insert  524  by cooperating threads on the exterior of rear connecting sleeve  534  and the interior of insert  524 . 
     The connector  520  is inserted into bores by simply axially thrusting the connector  520  into the bores with the center pin  527  being electrically and mechanically received by pin conductors. Flexibility of the barbs  536  permits tabs  538  to flex inwardly to permit insertion. The tabs  538  then flex outwardly to be captured within annular grooves of the jack. To retract the connector  520 , an operator simply pulls on outer jacket  522 . A slot defining edge  541  on reduced diameter portion  521  urges against the ramp of tabs  538  to force the tabs  538  inwardly out of their locking position in grooves  517 . This permits removal of the connector  520 . 
     FIGS. 5A-5D show various external views of an embodiment of the present invention for testing the coaxial connector of FIG.  1  and the coaxial cable extending from the connector. It is to be understood that embodiments of the present invention may be used with other styles of coaxial connectors in addition to the coaxial connector of FIG. 1, including BNC connectors. The testing device  100  includes an exterior housing  102 . The housing has a top face  130  that has two connector jacks  104  and  106  mounted to it. As shown one jack  104  is used to test pin height and concentricity. The other jack  106  is used to test electrical continuity and may be used to test concentricity to a finer precision. 
     Circuitry discussed below is included within the housing  102  and is associated with the first jack  104  and the second jack  106  to enable the various testing. A button  108  protrudes from the housing  102  and may be depressed by a user to activate the circuitry used to test continuity through the jack  106 . A pin height light  110 , such as a light emitting diode (LED), protrudes from the housing  102  to provide an external indication to the user when the pin height is sufficient in response to the user placing the connector on the jack  104 . A continuity pass light  112  provides an external indication to the user when the cable and connector continuity through jack  106  is satisfactory. Short circuit light  116  and open circuit light  114  provide an external indication to the user when the connector and/or cable provide a short circuit or open circuit, respectively. 
     FIGS. 6A-6C are various exploded views of the testing device  100 . The housing  102  includes a front piece  120  and a back piece  118  that are fastened together. A label  120 ′ may be placed on the front piece  120  to provide names for the lights so the user may correctly interpret each external indication. A battery  128 , such as a conventional 9V alkaline, may be stored within the housing  102  to provide power to the circuitry. The top piece  120  has a pin height light aperture  110 ′, a pass light aperture  112 ′, an open light aperture  114 ′, and a short light aperture  116 ′ that allow the associated LEDs to protrude. A button aperture  108 ′ is included in the top piece  120  to allow the button  108  to protrude. 
     The circuitry is provided on a printed circuit board  122 . A pin height switch  126  is included to facilitate testing of the pin height of the connector. The pin height switch includes a switch arm  125  that moves to close the switch  126  when the pin height is of sufficient length. A pin height shaft  140  that is included in the pin height connector  104  contacts the switch arm  125 . The center pin  527  of the connector  520  contacts the pin height shaft  140  and causes it to move which then moves the switch arm  125 . The movement of the switch arm  125  completes the circuit that causes the pin height LED  110  to light. 
     The pin height jack  104  includes an outer support surface  132  that threadedly engages a mounting shaft  131 , and the outer support surface  132  has slots  133  sized to received the barbs  538  to establish a slip-fit by allowing longitudinal movement of the connector  520  while limiting its rotation. The mounting shaft includes a support shaft that extends concentrically through the hole in the outer support surface  132 , which is more clearly shown in FIG.  13 . The support shaft has a concentric hole  104 ′ that acts as a center pin receptacle. The center pin  527  passes through the center pin receptacle  104 ′ and is supported by the support shaft as the center pin  527  contacts the pin height shaft  140 . The support shaft is sized to receive the inner portion of the sleeve  521  while receiving the center pin  527  through the center pin receptacle  104 ′. The outer support surface  132  is sized to receive the outer portion of sleeve  521 . 
     The mounting shaft  131  passes through an aperture  130 ′ in the top face  130  of the housing  102 . A nut  134  and lock washer  136  may be used to hold the jack  104  in place along with block  138 . Block  138  threadedly engages the mounting shaft  131  and also fastens to the front piece  120  and rear piece  118  of the housing  102 . The block  138  has a threaded aperture  137 , shown in FIG. 12, that allows the connector jack  104  to pass into the interior of the housing  102  and interact with the switch  136 . A continuity switch  124  is also included on the printed circuit board  122  and is operably connected to the button  108 . The continuity switch  124  completes a circuit when the button  108  is depressed, and the circuit then lights an indicator accordingly. 
     FIG. 7 shows the continuity jack  106  in greater detail. The continuity jack includes a threaded mounting shaft  141  and an outer support surface  142 . The outer support surface  142  is sized to receive the outer portion of the sleeve  521  of the connector  520 . The outer support surface includes slots  143  sized to receive the barbs to establish a slip-fit by allowing longitudinal movement of the connector  520  while limiting its rotation. A nut  144  and lock washer  146  may be threaded on the mounting shaft  141  to hold it in place within an aperture  130 ″ in the top piece  130 . A nut  162  with a cavity  162 ′ may be used to thread onto the mounting shaft  141  from the interior to lock the connector  106  in place. The cavity  162 ′ allows various components of the jack  106  to concentrically fit within the nut  162 . 
     A fitting  148  including a support shaft  168  fits concentrically within the mounting shaft  141 . The support shaft  168  has a hole  166  that acts as a center pin entryway for the center pin  527  of the connector  520 . A center pin receptacle  149  fits within the fitting  148  and receives the center pin  527  after it has passed through the center pin entryway  166 . A second fitting  152  engages the fitting  148  and has an internal shaft that surrounds the conductor  150  of the center pin receptacle  149 . 
     A ground ring  160  fits over the mounting shaft  141  and is held in place along with the fittings by the nut  162 . The ground ring  160  through the nut  162  and mounting shaft  141  is in electrical connection with the sleeve  521  of the connector  520  when installed on the jack  106 . A bend-conductor  164  passes through the cavity  162 ′ of the nut  162  and is electrically connected to the conductor  150 . The bend-conductor  164  is in electrical communication with the continuity circuitry on the printed circuit board  122 . The ground ring  160  is connected to circuit ground through ground conductor  161 . 
     Thus, the continuity circuitry attempts to pass electrical current through the bend-conductor  164 , the conductor  150 , and the center pin receptacle  149  and into the center pin  527 . The cable having connector  520  attached to jack  106  has a terminator on its other end and current flows through center pin  527  and the terminator and then back through the ground conductor to the sleeve  520 . Current then travels through the mounting shaft  141  to the ground ring  160  and to circuit ground. 
     FIGS. 8A-8C show various views of the assembled continuity jack  106 . The relative assembled position of the mounting shaft  141 , nut  144 , top piece  130 , ground ring  160 , nut  162 , support shaft  168 , fitting  152 , and bend-conductor  164  can be seen. The ground conductor terminal  160 ′ of the ground ring  160  for attachment to the ground conductor  161  can also be seen. FIG. 8D shows a cross-section taken through line  8 D— 8 D of FIG.  8 A. 
     As can be seen in FIG. 8D, the center pin entryway  166  has a diameter that is not greater than the inner diameter of the center pin receptacle  149 . Because the center pin  527  must pass through the entryway  166  prior to engaging the receptacle  149 , the pin  527  must have proper concentricity to pass through the hole once the sleeve  521  has engaged the outer part of support shaft  168 , and the outer surface of the receptacle  149  becomes inaccessible to the center pin  527 . Therefore, the center pin  527  cannot pass between the outer surface of receptacle  149  and the interior shaft of the support shaft  168 , and damage to the center pin  527  is avoided because the center pin  527  correctly enters the inner shaft of the receptacle  149 . 
     FIGS. 9A and 9B show the fitting  148  having the support shaft  168  and entryway  166 . The fitting  148  must act as an electrical insulator to prevent a short circuit between the center pin receptacle  149  and the mounting shaft  141 . DELRIN insulator is an example of a suitable material for the fittings. The fitting  148  has a pin entryway  166  having a diameter that is less than the inner shaft  169  of the fitting  148 . The inner shaft  169  houses the center pin receptacle  149 . As mentioned, the smaller diameter of entryway  166  prevents the center pin  527  from becoming misaligned before entering the receptacle  149 . Furthermore, the smaller diameter may ensure that the center pin  527  has a high degree of concentricity relative to the sleeve  521 . 
     The fitting  148  has a larger diameter shaft  147  at the end away from support shaft  168 . The larger diameter shaft  147  is sized to receive a small diameter end  151  of the second fitting  152  shown in FIGS. 11A and 11B. The larger diameter shaft  147  may have a flared end  147 ′ to facilitate assembly with the second shaft  152 . 
     FIGS. 10A and 10B show the mounting shaft  141  of the continuity jack  106 . The outer surface  142  and slots  143  of the mounting shaft  141  are also visible. The cross-section of the mounting shaft  141  taken through line  10 B— 10 B of FIG. 10C can be seen in FIG.  10 B. As mentioned, FIGS. 11A and 11B show the second fitting  152  and its smaller diameter end  151 . The second fitting  152  has an inner shaft  153  that houses the conductor  150  of the center pin receptacle  149 . 
     FIGS. 12A-12D show the block  138  used with the pin height jack  104 . The block  138  has a threaded aperture  137  for engaging the mounting shaft  131 . The block  138  has mounting apertures  138 ′ and  139  for receiving fasteners that hold the block  138  in place relative to the printed circuit board  122  and the housing  102 . A lip  138 ″ is included on the rear side of the block  138  which overhangs a top edge of the printed circuit board  122  to facilitate the proper positioning and the stabilization of the block  138  relative to the printed circuit board  122 . 
     FIG. 13 shows a cross section of the testing device  100  taken through the pin height jack  104 . As can be seen, the pin height jack  104  includes the outer surface  132 , the mounting shaft  131  with support shaft  131 ′ having a receptacle  104 ′ extending through the mounting shaft  131  until contacting the pin height shaft  140 . The mounting shaft  131  has an inner shaft of greater diameter than the center pin  527  for housing the pin height shaft  140  that also has a greater diameter than center pin  527 . The pin height shaft  140  passes through the aperture  130 ′ in the top piece  130  and then through the aperture  137  of the block  138  and contacts the switch arm  125  of pin height switch  126 . 
     The support shaft  131 ′ of the pin height jack  104  may be made of metal because conduction of electricity through the cable is not utilized for this test and an electrical short between the sleeve  521  and the center pin  527  is not a concern. The metal support shaft  131 ′ enhances the durability of the jack  104  when testing connectors  520  that are not sufficiently concentric. Thus, it may be desirable to test concentricity first by attempting to insert the connector  520  into the pin height jack  104  and then attempting to insert the connector  520  to the continuity jack  106 , which may test concentricity to a finer precision because the entryway  166  may be of a diameter that is less that the diameter of the center pin receptacle  104 ′ of the pin height jack  104 . 
     FIG. 14 shows a block diagram of the circuitry used by the testing device  100 . A 9 Volt battery  128  may be included to provide DC power to the pin height circuit and the continuity circuit. The pin height measurement circuit  172  includes the switch  126  that completes a circuit between the battery  128  and the pin height LED  110 . When the switch is closed by insertion of a connector  520  with proper center pin length, then the LED  110  lights. 
     The 9 Volt battery  128  is also connected to a standard linear voltage regulator  176 . The voltage regulator  176  receives voltage from the 9 Volt battery  128  when the user depresses the button  108  to close switch  124 . The voltage regulator  176  then provides a steady DC output of about 5 Volts to a cable resistance interface  178  that includes the bent-conductor  164  linked to the center pin receptacle  149 . This causes current to flow through the attached cable  170  and terminator  186 , which is typically 75 ohms for a standard coaxial cable. The voltage regulator  176  provides power to a window comparator  180  consisting of a dual comparator IC that receives the current passed through the cable. The window comparator  180  uses three separate windows with one window detecting a shorted condition, one window detecting a pass condition, and one window detecting an open condition. The output of each comparator feeds directly to the corresponding LED. 
     The duration timer  182 , such as a TL555C timer configured as a monostable multi-vibrator, also receives power from the regulator  175 . The duration timer  182  creates an interval that power is provided from the regulator for the LEDs to light. The LEDs may remain lit for the interval, such as 10 seconds, or until the button  108  is released, whichever is sooner. 
     For a standard coaxial cable and a 75 ohm terminator, a typical window range for determining a short circuit is 0 to 25 ohms detected resistance. A typical window range for determining a passing cable is 45 to 135 ohms detected resistance. A typical window range for determining an open circuit is greater than 175 ohms detected resistance. 
     Although the testing device  100  is shown with both a continuity and a pin height testing circuit, it should be understood that other embodiments may eliminate one or both of these circuits. Furthermore, it should be understood that one jack may be configured to perform all tests, rather than using two separate jacks. 
     While the invention has been particularly shown and described with reference to preferred embodiments thereof, it will be understood by those skilled in the art that various other changes in the form and details may be made therein without departing from the spirit and scope of the invention.