Coaxial Connector With An Integral Breakoff Terminating Resistor

Abstract

A coaxial connector with an integral breakoff terminating resistor is especially suitable for CATV systems in which the coaxial connector includes a body having a first portion containing a contact spring and a second portion in which a terminating resistor is disposed. An interface portion between the first and second body portions is formed of material having a thickness substantially less than the thickness of material used in either of the body portions mentioned above. When it is desired to remove the terminating resistor as, for example, when connecting a subscriber's coaxial cable drop line to a CATV system, a relatively small amount of mechanical force applied to the second body portion causes the interface to rupture or fracture so that the second body portion along with the terminating resistor is readily removed, thus exposing the center conductor contact spring and a threaded area on the first body portion for mating with a companion connector that is attached to the subscriber's coaxial drop cable.

Description

BACKGROUND OF THE INVENTION

In the cause of construction and operation of a modern Community Antenna Television (CATV) System, sometimes referred to as Cable Television, it becomes necessary to terminate the unused subscriber coaxial connection provisions in the system's characteristic impedance. The characteristic impedance in a CATV system is typically 75 ohms. For example, all coaxial cable, active and passive electronic devices used in the system are electrically designed to function with an impedance of 75 ohms.

A modern system is laid out and constructed with provisions for a coaxial cable connection to each potential subscriber that is passed by the cable system. Such layout and construction practice is known in the industry as a dedicated plant.

Upon completion of the system construction task it then becomes necessary to electronically and electrically balance the CATV system. It is at this time that the subscriber's coaxial connection provisions must be terminated in the system's characteristic impedance. The subscriber coaxial connection provisions are usually located in a passive electronic device known in the industry as a directional tap. The coaxial connection provisions consist of a threaded coaxial connector generally known in the CATV industry as a G61 chassis connector which is integrated into the directional tap housing. Directional taps are manufactured with from two to eight such connectors; with four connectors being the most commonly used configuration. There are various physical differences in the outward appearance of the G61 type fitting; however, the portion of the fitting that is exposed for connection to the subscriber's coaxial drop cable has been standardized by the CATV industry. It is at the above described connector that the 75 ohm terminating resistor is applied. In current industry practice, the terminating resistor is axially located in a threaded housing in which the resistor leads become the center conductor and the housing the outer conductor. A terminating resistor assembly of the type just described is known in the industry as a TR59 terminator. The thread in the TR59 terminator housing mates with the thread on the G61 chassis connector.

Subscriber coaxial cable connections are made upon completion of the electrical balancing of the system, at which time the terminating resistor is removed from, and the subscriber's coaxial drop cable is then attached to, the subscriber's coaxial connection.

As additional subscribers are connected to the system, more terminating resistors are removed with the subscriber's coaxial drop cable replacing them. The unused subscriber coaxial cable connection provisions at the directional tap must remain terminated.

Considering that the average CATV system being constructed connects less than 25 percent of its potential customers, it becomes apparent that approximately 75 percent of the directional tap subscriber coaxial connection provisions must remain terminated.

The cost associated with the termination requirements of a typical CATV system represents a considerable investment in facilities and labor to the owner of a CATV system.

Typical steps in the manufacture and installation of a CATV directional taps which contain the subscriber's coaxial connection provisions include the following. First, in manufacturing the directional tap, usually after final assembly, a terminating device is attached to each subscriber coaxial connection for the purpose of testing the performance of the directional tap assembly. The terminating device, in this instance, consists of a suitable holder containing a terminating resistor. After testing, the terminating device is removed. Subsequently, when the directional taps are installed in the CATV system it is again necessary to install terminating devices as described earlier in this section.

It can be seen, therefore, that in the manufacture of directional taps for CATV systems and during the construction and balancing of the CATV system in which the directional taps are installed, considerable labor is required in respect to the application, removal and general use of terminating devices.

In the event that should it be desired to disconnect a subscriber's coaxial drop cable from the CATV system at the directional tap connector, that connector may again be terminated through the application of a TR59 terminator which was previously described.

BRIEF SUMMARY OF THE INVENTION

Accordingly, it is an object of this invention to provide a coaxial connector, for use in conjunction with devices such as CATV directional taps, which connector is pre-terminated in the characteristic impedance of the system in which it will be used.

It is another object of this invention to provide such a pre-terminated coaxial connector in which the terminating resistor is easily removed when desired for the purpose of making subscriber connections to the CATV system.

It is another object of this invention to provide such a pre-terminated coaxial connector in which the connector will remain waterproof so long as the pre-terminated resistor has not been removed from the assembly.

It is another object of this invention to provide such a pre-terminated coaxial connector in which the connector, once the pre-terminating resistor is removed, will be compatible with mating connection devices commonly used in the industry.

Other advantages and objects of the invention will appear from the following description taken in conjunction with the drawings.

In accordance with one embodiment of the invention there is provided a coaxial connector for use in a signal distribution system of the type having a transmission line extending from a directional tap housing or junction box with the tap housing mounting a plurality of coaxial connectors, each capable of being connected or coupled to a separate transmission line. Each coaxial connector comprises a body with a first portion, a second portion and an interface portion integral with and joining the second portion to the first portion. The first portion mounts an insulator and spring contact and the second body portion mounts a terminating resistor having a pair of leads with one of the leads being connected to the second body portion and the other of the leads extending into the first body portion and being electrically connected with the spring contact therein. The interface portion of the body is formed of a material substantially thinner than the first and second body portions and is adapted to rupture or fracture upon the application of a deflecting force to the second body portion to thereby readily remove the second body portion along with the terminating resistor contained therein.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a top plan view of a typical directional tap housing partially broken away illustrating the manner in which the coaxial connector with integral breakoff resistor is mounted to the housing.

FIG. 2 is a sectional view of one of the coaxial connectors with integral breakoff terminating resistor taken along the lines 2--2 of FIG. 1.

FIG. 3 is a sectional view taken along the lines 3--3 of FIG. 1 and illustrating a coaxial connector with IBTR after a portion of its body along with the terminating resistor and thread protector have been removed .

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Turning now to FIG. 1, there is shown a top plan view of a commonly used directional tap housing 11 which is partially broken away to illustrate the manner in which the coaxial connector with integral breakoff terminating resistors 12 through 15 are mounted in a wall 11a thereof. The directional tap housing 11 includes a cover 16 hinged by hinge assembly 17 and having means such as bolt 18 to secure the cover in place. Provision is made for mounting the tap housing to a messenger strand such as by a clamp assembly 19.

Referring to FIG. 2, which is a cross section taken along the lines 2--2 of FIG. 1, there is shown in detail the coaxial connector with integral breakoff terminating resistor in accordance with this invention. There is provided a body 21 having a first portion 21a, a second portion 21b and an interface portion 21c joining the first and second portions together, The body portion 21a is hollow and contains an insulator 22 which surrounds, holds and locates a contact spring 23. The insulator 22 and hence the contact spring 23 are retained in the hollow body portion 21a by means such as a retaining lip 21d formed in the body portion 21a.

The portion 21b is also hollow and includes a hollow resistor lead receiving portion 21e having a sealed end. A terminating resistor 24 having leads 26 and 27 is disposed within the hollow body portion 21a. The lead 26 of terminating resistor 24 extends into the hollow lead receiving portion 21e of the second body portion 21b. The lead 26 is mechanically and electrically connected to the body 21 through suitable connection to the body portion 21e. Suitable connection includes soldering or cold-staking the body portion 21e to the lead 26. Cold-staking has the advantage of avoiding any possible heat damage to the terminating resistor 24 which might occur during soldering. The other lead 27 of terminating resistor 24 extends into and makes electrical contact with the contact spring 23.

The first body portion 21a of the coaxial connector shown in FIG. 2 includes a threaded portion generally indicated by reference numeral 21f and includes a flange portion 21g. A washer 28 is disposed between the flange portion 21g and the wall 11a of directional tap housing 11 in order to prevent the entry of water into the tap housing 11 and the coaxial connector is mounted to the wall 11a by a nut 29 screwed on to the threaded portion 21f.

The body 21 may also include a threaded portion generally indicated by reference numeral 21h for the purpose of receiving a mating connector 33 that is attached to the subscriber's coaxial drop cable 32 when such drop cable is installed. A suitable thread protector 31 (plastic, for example) is disposed over these exposed threads 21h and can extend over and enclose the body portions 21b and 21e.

As shown in FIG. 2 and in accordance with the invention, the interface portion 21c of body 21 which joins the first body portion 21a to the second body portion 21b is substantially thinner than both body portions 21a and 21b. Also, in the specific embodiment shown in FIG. 2 this interface portion 21c is indicated as an indentation which can be a notch or groove formed therein and which is generally indicated by reference numeral 34.

Thus construction of the coaxial connector such as shown in FIG. 2 in accordance with this invention provides a coaxial connector which contains an integral terminating resistor for terminating the subscriber's coaxial cable connection provisions in a directional tap in the CATV system's characteristic impedance.

When it is desired to remove the terminating resistor from one of the coaxial connectors constructed in accordance with this invention, as for example, as in the case for a CATV system when a subscriber's coaxial drop cable is to be attached to the coaxial connector, a lateral deflecting force is applied to the body portion 21b. This is illustrated in FIG. 1 by an arrow indicating force applied to the coaxial connector 13 shown in FIG. 1. This lateral displacement force can be applied, for example, by simply displacing the body portion 21b with a pair of pliers or other suitable device and results in rupture or fracture of the body 21 at the interface portion 21c between first body portion 21a and second body portion 21b. The presence of an indentation such as a notch or groove 34 facilitates such rupture or fracture. However, the second body portion 21b can be broken off at 21c even though the indentation at 34 is not present because the reduced cross-sectional area of the body material at the interface 21c will fracture at the point indicated as the groove numeral 34. With such fracture of the interface body portion 21c, the second body portion 21b and the terminating resistor 24 are completely separated from the first body portion 21a. The force applied to the second body portion 21b also causes the thread protector 31 (if one is used) to be stripped off the threaded portion 21h of body 21 as well as withdrawing the lead 27 of terminating resistor 24 from the contact spring 23. This results in complete separation of the body portion 21b and the thread protector 31 along with the integrally contained terminating resistor 24 from the first body portion 21a. This is illustrated in FIG. 3. A coaxial cable such as subscriber's coaxial drop cable in the case of a CATV system can then be connected to the coaxial connector at the directional tap from which the terminating resistor has been removed. Thus in FIG. 1 a coaxial cable such as the suscriber's coaxial drop cable 32 having a mating coaxial connector 33 is shown connected to the directional tap 11 through coaxial connector 12.

What has been described is an improved electrical coupling device or coaxial connector for signal distribution systems such as a CATV system in which the coaxial connector is pre-terminated and in which the terminating means can be quickly and easily removed when it is desired to connect a subscriber's coaxial drop cable to the directional tap. Incorporation of a coaxial connector with an integral breakoff terminating resistor into a directional tap at the time of manufacture leads to a saving in time and labor. Thus, upon completion of the manufacture of a directional tap it is not necessary to attach a separate terminating resistor to the directional tap in order to test it, since it already contains an integral terminating resistor. Subsequently, upon installation of a directional tap containing the coaxial connector described herein into a signal distribution system such as a CATV system, it is further not necessary to connect terminating resistors to all of the subscriber's coaxial cable connectors of the system in order to test the system since each of the coaxial connectors already contain an integral terminating resistor. Also, since the first and second body portions including the hollow lead receiving portion 21e are integral with each other, and the end of the lead receiving portion is sealed, the pre-terminated coaxial connector is waterproof. After construction and test of a signal distribution system, when it is desired to connect the subscriber's coaxial drop cables to the directional taps, removal of the integral terminating resistors is quickly and easily accomplished. Merely applying a deflecting force to an extending body portion of the coaxial connector ruptures or fractures the body at a specific location, thereby detaching a portion of the body and a terminating resistor contained therein.

While the invention has been described and illustrated with respect to a specific embodiment, it should be obvious to those skilled in the art that various modifications may be made to the specific embodiment disclosed herein without departing from the true spirit and scope of the invention.

Claims

I claim:

1. A coaxial connector for use in a signal distribution system of the type having a transmission line extending from a directional tap housing with the tap housing mounting a plurality of coaxial connectors each of which is capable of being coupled to a transmission line, the coaxial connector comprising a body having a hollow first portion, a hollow second portion and an interface portion integral with and joining said second portion to said first portion, said interface portion being formed of material substantially thinner than said first and second body portions, a spring contact, an insulator surrounding said spring contact, said insulator and spring contact being disposed within said hollow first portion of said body, a terminating resistor having a pair of leads, said terminating resistor disposed within said hollow second portion of said body and one of said pair of leads being electrically connected to said second portion of said body and the other of said pair of leads extending into and being electrically connected to said spring contact.

2. A coaxial connector in accordance with claim 1 wherein said interface portion of said body has an indentation formed therein for facilitating rupture of said interface portion in response to mechanical deflection of said second portion of said body to separate said second body portion from said first body portion.

3. A coaxial connector in accordance with claim 1 wherein said interface portion of said body has a notch formed therein for facilitating rupture of said interface portion in response to mechanical deflection of said second portion of said body to separate said second body portion from said first body portion.

4. A coaxial connector in accordance with claim 1 in which said second portion of said body has a hollow lead receiving portion for receiving said one of said resistor leads with said lead receiving portion being staked to said one resistor lead to provide mechanical and electrical interconnection therebetween.

5. A coaxial connector in accordance with claim 1 in which said first body portion includes a retaining lip which is bent over said insulator to retain it within said first body portion.

6. A coaxial connector in accordance with claim 1 in which a portion of said first body portion is threaded and including a removable thread protector fitted over said second body portion and said threaded portion of said first body portion.

7. A coaxial connector in accordance with claim 4 wherein said hollow lead receiving portion has a sealed end whereby the coaxial connector is waterproof.