EP2339703A1

EP2339703A1 - Test point adaptor for coaxial cable connections

Info

Publication number: EP2339703A1
Application number: EP09180645A
Authority: EP
Inventors: Kim Lundgren Eriksen
Original assignee: PPC Broadband Inc
Current assignee: PPC Broadband Inc
Priority date: 2009-12-23
Filing date: 2009-12-23
Publication date: 2011-06-29
Anticipated expiration: 2029-12-23
Also published as: TW201136073A; DK2339703T3; CN102185228A; EP2339703B1; WO2011079196A1

Abstract

A test point adaptor (1) for coaxial cables. The test point adaptor may comprise a main body (2) having a longitudinal axis with a first end (3) comprising a first interface (4) and a second end (5) comprising a second interface (6) and a first center conductor (7) extending at least from the first interface to the second interface. Further, the test point adaptor may comprise a test body (11) having a longitudinal axis arranged laterally to the main body. The test body comprises a first test body end (13) and a second test body end (14) comprising a third interface (15), and an electrically conductive contact member (20). The contact member is in electrical contact with the first center conductor so as to allow rotation of the main body relative to the first center conductor.

Description

The present invention relates to a test point adaptor for coaxial cables. The invention further relates to the use of a test point adaptor for testing cables.

Background of the invention

Test adaptors or test point adaptors are used in order to test the properties of communication networks such as cable TV and computer networks e.g. using coaxial cables. In order to carry out a test, it is necessary to provide access points in which test equipment may be connected.
Testing of the coaxial cables has become increasingly important due to the fact that more and more digital signals are carried in the cable. Disturbance in the signal i.e. the signal/noise ratio, in digital signals are more likely to occur than when only analogue signals were used, and ensuring a high quality of the cables including connectors have thus become increasingly critical. Furthermore, the end user of a connection is depending more and more on the reliability of their connection e.g. by using IP-telephony, VPN and similar products and does not accept line dropout e.g. when testing the connection. Thus, e.g. Internet Service Providers demand increased testing of the lines in order to ensure that they will be able to supply their service with a desired quality of service and without dropouts.
A system as described in US 4,738,009 , is a system that rely on removing a part of the dielectric material. This invasive method is likely to cause disturbance in the connection, in particular considering the digital signals. If the grip around the cable is loosened the twisting of T-connector could cause damage to the conductors. Connecting and disconnecting test equipment would eventually cause twisting of the T-connector.
Typically, when inserting test equipment, the coaxial cable is disconnected from e.g. an amplifier or similar equipment that the coaxial cable is connected to. Various components are assembled to achieve an adaptor having an access point for testing, said adaptor being inserted between the coaxial able and e.g. an amplifier, and in this way such adaptor provides for testing during use of the cable. However, when the number of parts assembled for such adaptor increases, the risk of poor performance and disruption of the signal increases similarly. Furthermore, the persons installing the adaptor and connecting the test equipment thereto need to pay great attention to correct assembly of the adaptor and to use the equipment carefully.
In order to facilitate easy access when connecting the test equipment to the adaptor in question, the person installing the equipment often adjusts the position of the access point e.g. by rotating the access point to which the test equipment is connected. This, however, often causes disruption to the signal quality which are not corrected after having performed the desired tests. Typically, the damages to the cables and/or the connection are not visible to the person handling the equipment and thus the mere installation of today's test equipment could cause a poor signal quality.
Thus, it is an aspect of the present invention to provide a test point adaptor that causes a minimal disruption of the signal to be measured.
This aspect is obtained by a test point adaptor for coaxial cables. The test point adaptor may comprise a main body having a longitudinal axis with a first end comprising a first interface and a second end comprising a second interface and a first center conductor extending at least from the first interface to the second interface. Further, the test point adaptor may comprise a test body having a longitudinal axis arranged laterally to the main body. The test body comprises a first test body end and a second test body end comprising a third interface, and an electrically conductive contact member. The contact member is in electrical contact with the first center conductor so as to allow rotation of the main body relative to the first center conductor. The first end of the main body may be named the first body end.
When the main body and thus the test body are rotated, and the first center conductor is fixed in relation to the two bodies, the first center conductor and the contact member are rotated in relation to each other. Thus, it is not possible for the connection between the first center conductor and the contact member to be rigid, e.g. by soldering them together. When the test point adaptor is in its mounted position, the center conductor is fixed, e.g. inside an amplifier, in order to achieve a firm connection. If the main body is provided with insulators for positioning the first center conductor in the main body, the insulators will rotate either relative to the main body, or the insulators will rotate along with the main body relative to the first center conductor.
In an embodiment, the contact between the first center conductor and the contact member may be provided by a sliding contact.
By using a sliding contact between the first center conductor and the contact member, it is achieved that the main body can rotate freely around the first center conductor and thus maintaining an electrical connection to the contact member. Typically, the first center conductor is symmetrical around its longitudinal axis, i.e. having a circular cross section.
In an embodiment, the contact member may be spring loaded.
By using a spring, it is achieved that the contact is preserved despite tolerances of the center conductor. Likewise, the contact between the first center conductor and the contact member i.e. the sliding contact may be obtained by resilient means, e.g. rubber, disk spring or coiled spring. The spring may be an annular spring plate. The spring may be positioned between a seizure positioning the end of the second center conductor in relation to the first center conductor and the second end of the test body.
In an embodiment, the first interface may comprise, in relation to the main body, rotatably arranged connecting means for connecting the first interface to a mating part, e.g. an amplifier.
Rotatably arranged connecting means or interface may e.g. be named a swivel nut or swivel member. In this way, it is possible for the main body to rotate although the first center conductor is kept fixed. When providing a swivel nut, the main body rotates in relation to the swivel nut. The first center conductor is arranged such that force necessary for rotating the first center conductor relative to the main body is smaller than either the force for preventing the first center conductor from rotating in the insulators or preventing the insulators holding the first center conductor from rotating in the main body. Thus, the first center conductor may be kept fixed relative to the main body when rotating the main body.
In an embodiment, the test point adaptor may comprise:

a swivel member defining a central axis and having first and second opposing ends, the first end having an outer and an inner surface and a threaded region for threadingly engaging the first end of the swivel member with a matching threaded portion of a mating component,
a main body having first and second opposing body ends and a central bore defining a longitudinal axis which is coaxial with the central axis of the swivel member, the first body end having an outer cylindrical surface,
a first center conductor extending along the longitudinal axis, and
a nut having a central aperture defining an inner surface and first and second opposing side walls, the first side wall being adapted to slidingly engage and abut the mating component, and an inner inclining surface region,

In this way, it is achieved that the main body of the test point adaptor can be manufactured in one piece, thus minimising the risk of moist, dirt, and/or water penetrating to the inside of the main body. Furthermore, during installation of the test point adaptor to a mating component, only the nut and the swivel member is turned and the main body as well as the cable is kept still. Thus, damage to the cable and the first center conductor is avoided.
In one embodiment, the second end of the swivel member may comprise at least one slit in order to allow the second end of the swivel member to be compressed. The at least one slit facilitates compression of the second end of the swivel member. In this way, the second end can be compressed so as to achieve a tight connection to the main body. The at least one slit may be obtained e.g. by cutting or milling or, if the swivel member is moulded, it may be obtained in the moulding process.
In an embodiment, the first interface may comprise a male part with outer connecting means, such as a thread. The first interface may comprise a swivel member or a swivel nut.
In an embodiment, the test body may comprise a resistor.
In an embodiment, the resistor and the test body may be releasably connected. In an embodiment, the resistor may be releasably connected to the test body.
In this way, it is possible to adjust the properties of the test body, i.e. the measuring properties of the test point adaptor, to the specific measuring equipment and/or the specific connection to be tested.
In an embodiment, the test body and the main body may be threadably engaged with each other.
In an embodiment, the test body may be arranged substantially perpendicular to the main body.
In an embodiment, the connection between the test body and the main body may comprise sealing means.
In an embodiment, the sealing means may comprise an adhesive. Having threadably engaged the test body and the main body, an adhesive may be applied in order to achieve a tight sealing between the two bodies.
In an embodiment, the contact member may comprise a central aperture arranged such as to receive one end of a resistor. In this way, it is possible to achieve a firm electrical contact between the contact member and the resistor.
In an embodiment, the contact member may be arranged in a seizure. In this way it is possible to use different material for the seizure and the contact member. The contact member may be made of brass or plated brass. The contact member may be made of material similar to the center conductor of the main body.
In an embodiment, the seizure may be movably arranged in the first end of the test body. In this way, the seizure is easy to install and is capable of moving along the longitudinal axis of the test body without being rotated. Furthermore, if necessary, the movable arrangement of the seizure may allow headroom for the spring to work.
In an embodiment, the seizure may be made of a dielectric material. In this way, it is achieved that the contact member is kept in position without short circuiting between the first center conductor and either of the bodies.
In an embodiment, the test body may comprise an inner compartment for receiving a test instrument.
In an embodiment, the contact member may have flexible fingers arranged so as to clamp around the one end of a resistor. In this way, a firm electrical contact is established between the contact member and the resistor.
In an embodiment, the contact member may have projections for applying a pressure against the inner walls of the seizure. In this way it is achieved that the contact member is fixed in the seizure.
In an embodiment, the test body may comprise a cap for sealing the inner compartment of the test body. The cap may comprise a terminator for stopping the signal.
An aspect of the invention relates to the use of a test point adaptor. The test point adaptor may be used for testing connections using both coaxial cables and/or fiber.
In an embodiment, the test point adaptor may be used for testing connections using both coaxial cables and fiber and combinations thereof.
In an embodiment, the sealing means of the test point adaptor may comprise an O-ring.
The present invention is to be described in detail with reference to the accompanying drawings, in which:

Fig. 1 shows an embodiment of a test point adaptor according to the invention,
Fig. 2 shows a cross sectional view of the test point adaptor of Fig. 1,
Fig. 3A shows a seizure for a test point adaptor,
Fig. 3B shows a contact member for a test point adaptor,
Fig. 3C shows an embodiment of a spring.
Fig. 3D shows an exploded view of an embodiment of the test body and its components,
Fig. 4 shows a test point adaptor in its mounted position, and
Fig. 5 shows an embodiment of swivel member.

Fig. 1 shows an embodiment of the test point adaptor 1 having a main body 2 including a first end 3 comprising a first interface 4, in this embodiment a swivel member or swivel nut, and a second end 5 comprising a second interface 6. A first center conductor 7 is arranged in the main body 2 extending beyond the first end 3. A test body 11 is attached to the main body 2. The test body 11 has a first test body end 13 (better seen in Fig. 2) screwed into the main body 2 and a second test body end 14 comprising a third interface 15 (better seen in Fig. 2). The test point adaptor 1 is shown having male threaded interfaces 4,6, however, the interfaces may be female threads or they may be other kinds of engaging means.
In a cross sectional view of Fig. 1, Fig. 2 shows an embodiment of a test point adaptor 1 comprising a main body 2 having a first end 3 with a first interface 4, a swivel member or swivel nut, and a second end 5 with a second interface 6. A first center conductor 7 is arranged along the longitudinal axis 8 of the main body 2. The first center conductor 7 is kept substantially in the center of the main body 2 by a first seizure 9 and a second seizure 10. A test body 11 having a longitudinal axis 12 is mounted laterally to the main body 2. The test body 2 is shown with a slightly changed outer outline compared to Fig. 1. The test body 11 may be arranged in other ways than substantially perpendicular to the main body 2, e.g. in an angle of 15° - 90° or such as 25° - 80°, such as 35°- 70° such as 35°- 55°. The test body 11 has a first test body end 13 and a second test body end 14 having a third interface 15. The first test body end 13 is threadably engaged with the main body 2. A seizure 16 is mounted at the first test body end 13. The seizure 16 is provided with an annular projection 17. A spring 19 is arranged between the annular projection 17 of the seizure 16 and the end rim 18 of the first test body end 13. The seizure 16 is arranged so as to be able to move along the longitudinal axis 12 of the test body 11. The spring 19, in this embodiment an annular spring washer, facilitates that the seizure 16 is forced along the longitudinal axis 12 of the test body in the direction away from the second end 14 of the test body 11. A contact member 20 is inserted in a central seizure aperture 21 of the seizure 16. The contact member 20 is provided with a central aperture for receiving the one end of a resistor 23 or similar. Having positioned the first resistor end 24 in the central seizure aperture 21 of the seizure 16, the central aperture 22 of the contact member 20 is arranged to receive the first resistor end 24. When the contact member 20 is inserted in the central seizure aperture 21 of the seizure, the contact member 20 clamps around the first resistor end 24. Thus, the first resistor end 24 is kept in position and the contact member 20 is fixed in the central aperture of the seizure 16. As the contact member 20 is electrically conductive, the resistor 23 is in electrical contact with objects being in contact with the contact member 20. The resistor 23 extends internally in the test body 11 along the longitudinal axis 12. At the second end 14 of the test body 11, the resistor is kept in position by a gripping arrangement 25. The gripping arrangement 25 is provided with a central aperture 26. The central aperture 26 is arranged so as to receive a second resistor end 27. The gripping arrangement 25 further facilitates that the center pin of a test equipment (not shown) may be inserted in electrical contact with the resistor 23. In Fig. 2 the second test body end 14 of the test body 11 is terminated by a removable cap 28 comprising a terminator 29. The cap 28 is threadably engaged with the third interface 15 of the second test body end 14. The cap 28 may be connected to the third interface 15 in other ways, e.g. by hatches or a quarter turn key and slot. A sealing means 30 ensures that the sealing of the third interface 15 by the cap 28 is watertight. Further, in order to achieve watertight connections, the test point adaptor 1 is in this embodiment provided with O- rings 31, 32, 33.
The described embodiment of the test body 11 and its components provide electrical contact between a test instrument (not shown) connected at the second end 14 of the test body and the contact member 20. Thus, a second center conductor is provided.
The contact member 20 is in contact with the first center conductor 8 arranged in the main body 2.
In another embodiment of the present invention, the resistor 23 and the gripping arrangement 25 may be provided as an integrated part of the test equipment (not shown). In such embodiment the contact member 20 may be arranged such as to receive a second center conductor from the test equipment.
Fig. 3A shows the seizure 16 for mounting in the first test body end 13. The seizure 16 is provided with an annular projection 17. Furthermore, the seizure 16 is provided with a central seizure aperture 21 having an internal surface 38 for receiving the contact member 20. A rim area 34 is provided on a seizure 16 projecting from the main seizure end 35 around the central seizure aperture 21. The rim area 34 may be situated on the end of a tube end. The seizure 16 may be made of a dielectric material. The dimensions of the seizure 16 is made such as to mount the seizure 16 in the test body 11 and still allowing the seizure 16 to move along the longitudinal axis of the test body 11 according to the flexibility of the spring 19 (shown in Fig. 3C). In another embodiment of the seizure 16, the rim area may be substantially in level with the main seizure end 35.
Fig. 3B shows an embodiment of the contact member 20. In order for the contact member to facilitate clamping around a resistor end (as shown in Fig. 2), slits 36 are cut in the contact member and thus fingers 37 are formed. The fingers 37 may each have a projection 38 for pressing against the internal surface 38 of the central aperture of the seizure 16. During assembling, the tapered outline of the first contact member end 39 provides an easy insertion of the contact member 20 into the central aperture 22 of the seizure 16. When pressing the contact member 20 further into the central aperture 22 of the seizure 16, the fingers 37 are forced to bend radially inwardly by the projections 38 and thus clamp around the resistor end (not shown). A second contact member end 40 is substantially flat in order to achieve contact with the first center conductor 8 positioned in the main body 2. The second contact end 40 may in other embodiments be convex.
Fig. 3C shows an embodiment of a spring washer 19 for providing a spring force so as to keep the contact member 20 in electrical contact with the first center conductor 8. The spring force may be provided by other resilient means such as rubber or other kinds of springs.
Fig. 3D shows an embodiment of the parts of the test body 11. The cap 29 is to be mounted on the test body 11 and the connection between the cap 29 and the test body may be sealed by the sealing means 30. Inside the test body 11, the gripping arrangement 25 serves to grip around the second end of the resistor 23. The O-ring 31 seals the connection between the test body 11 and the main body 2 (not shown). The first end of the resistor 23 is inserted through the seizure 16 and into the center aperture of the seizure where it is received by the contact member 20. When the contact member 20 is inserted in the central seizure aperture, the fingers of the contact member 20 are bend radially inwardly and brought to clamp around the first end of the resistor 23. The seizure 16 is positioned in the test body 11 having the spring 19 between the rim of the test body and the annular projection of the seizure 16. The seizure 16 may fit into the first end of the test body 11 in such way that the seizure can move if a force is applied, e.g. from the spring 19. If no force is applied, the friction between the seizure and the test body 11 will cause the seizure to remain in its position when mounted in the test body 11. The gripping arrangement 25 may be so arranged as to provide a possibility for movement of the resistor 23 relative to the test body 11.
Fig. 4 illustrates the test point adaptor 1 mounted on a mating component 41, e.g. an amplifier 41 (only a section shown). The interface 4, i.e. the swivel member or swivel nut, of the first end of the main body 2 is mounted in the mating interface 42 of the mating component, i.e. the amplifier 41. The center conductor 7 is fixed in relation to the amplifier by the screw 43. The screw 43 clamps strongly around the center conductor 7 (a pin) and when fixed, the center conductor 7 cannot rotate relative to the amplifier. Even if the test point adaptor 1 is rotated (see arrow A1) relative to the amplifier 41, the center conductor 7 will remain in a fixed position relative to the amplifier 41. Due to the fact that the first interface 4 comprises a swivel nut 44, it is possible to rotate the main body 2 and hence the test body 11 around the longitudinal axis 8 of the main body 2 without causing the main body 2 to move along the longitudinal axis 8 (in the direction of A2). Hence, the risk of displacement of the seizures 9, 10 is minimised. The main body 2 simply swivels relative to the swivel nut 44. The center conductor 7 is kept fixed by the screw 43 and thus the center conductor 7 is kept fixed relative to the seizures 9, 10, the seizures 9, 10 being rotated along with the main body 2. In another embodiment, the seizures 9, 10 may be fixed relative to the main body 2 when the main body is rotated. If the main body 2 is moved relative to the center conductor 7, the inner conductor of the cable (not shown) connected to the test point adaptor at the second end 5 is drawn out of the clamping mechanism 45 on the center conductor 7.
When the main body 2 and thus the test body 11 are rotated relative to the center conductor 7, the contact member 20 slides on the center conductor 7. By the spring 19 it is achieved that a firm contact is obtained between the center conductor 7 and the contact member 20. Thus, it is achieved that a test instrument coupled to the test body 11 may be brought in electrical contact with the center conductor 7. This contact is maintained irrespective of the position in which the test body 11 is oriented relative to the center conductor 7. Fig. 4 shows the test point adaptor 1 having a cap 29 mounted on the test body 11. When the test point adaptor is in use during a test, the cap 29 is removed and a test instrument is connected to the third interface (15).
Fig. 3 shows a sectional view of the test point adaptor of Fig. 2 in order to show the swivel member 4 further. Only a part of the test point adaptor 1 is shown. The part shown is when it is not connected to a mating component. Encircled by a dotted line, an enlarged view is shown in uncompressed state of the position of the main body 2, the nut 103 and the swivel member 4 in relation to each other , i.e. when the test point adaptor 1 is not mounted to a mating component (not shown). In this state, it is seen that a first play 1035 is present between the outer conical region 1024 of the swivel member 4 and the inner inclining surface region 1025 of the nut 103. A second play 1036 is seen between the recessed region 1018 of outer cylindrical surface 1015 and a part of the inner surface of the compressible second end 1022 of the swivel member 4. Furthermore, it is seen that an inwardly extending projection 1037 of the swivel member 4 is positioned in such a manner that the swivel member 4 cannot slide off the main body 2. This has the effect that when the threaded region of the swivel member 4 is connected to a mating component (not shown) and the nut 103 is turned in order to draw the swivel member 4 into the mating component, the first side wall 1025 will be brought into contact with the mating component. In relation to the mating component, the nut 103 will be in a fixed position when it is in contact with the mating component.
As a consequence, the swivel member 4 will slide towards the mating component, i.e. away from the second end 106 of the main body 2, and the swivel member 4 will thus slide relative to the nut 103 along the longitudinal axis of the main body 2. This relative movement of the swivel member 4 and the nut 3 will bring the outer inclining surface region 1024 of the compressible second end 1022 of the swivel member 4 in contact with the inner inclining surface region 1025 of the nut 3. The inclination of the inclining regions 1024, 1025 will have a resulting force that will press the inwardly extending projection 1037 radially towards the longitudinal axis 8 of the main body 2. The compressibility of the second end 1022 of the swivel member 4 facilitates that only a small torque is to be applied to the nut 103 in order to achieve a firm connection between the test point adaptor 1 (only partly shown) and the mating component (not shown).

Claims

A test point adaptor for coaxial cables comprising
- a main body having a longitudinal axis

- a first end comprising a first interface,

- a second end comprising a second interface,

- a first center conductor extending at least from the first interface to the second interface,

- a test body having a longitudinal axis arranged laterally to the main body, said test body comprising:

- a first test body end,

- a second test body end comprising a third interface, and

- an electrically conductive contact member,
wherein the contact member is in electrical contact with the first center conductor so as to allow rotation of the main body relative to the first center conductor.
A test point adaptor according to claim 1, wherein the contact between the first center conductor and the contact member is provided by a sliding contact.
A test point adaptor according to claim 1 or 2, wherein the contact member is spring loaded.
A test point adaptor according to claim 1, 2 or 3, wherein the first interface comprises, in relation to the main body, rotatably arranged connecting means for connecting the first interface to a mating part.
A test point adaptor according to any of the preceding claims 1 - 4, wherein the first interface comprises a male part with outer connecting means.
A test point adaptor according to any of the preceding claims 1 - 5, wherein the test body comprises a resistor.
A test point adaptor according to claim 6, wherein the resistor is releasably connected to the test body.
A test point adaptor (1) according to any of the preceding claims 1 - 7, wherein the test body and the main body are threadably engaged with each other.
A test point adaptor (1) according to any of the preceding claims 1 - 8, wherein the test body is arranged substantially perpendicular to the main body.
A test point adaptor (1) according to any of the preceding claims 1 - 9, wherein the connection between the test body and the main body comprises sealing means.
A test point adaptor (1) according to claim 10, wherein the sealing means comprises an adhesive.
A test point adaptor according to any of the preceding claims 1-11, wherein the contact member comprises a central aperture arranged such as to receive one end of a resistor.
A test point adaptor according to any of the preceding claims 1-12, wherein the contact member is arranged in a seizure.
A test point adaptor according to claim 13, wherein the seizure is movably arranged in the first end of the test body.
A test point adaptor according to claim 13 or 14, wherein the seizure is made of a dielectric material.