Keyed Plug Resistor

Abstract

A plug device for use in conjunction with radio and television frequency circuits and coaxial cable applications is disclosed. The plug features a load resistor with one lead secured to the body of the plug and another lead adapted to insertably engage the contact-receiving member of a receptacle in a component. The resistor serves to load and subsequently balance the circuit to prevent signal distortion in house droplines or in the continuing remainder of the circuit. The plug also features a rotatable hardened shell which surrounds the body of the device and which rotates relative to the body. Keying means, including cooperating hole means between shell and body and a special keyed wrench device, provide a means by which the plug device may be removed, once installed. This rotatable shell feature in a plug device discourages illegal tampering with electronic equipment, such as theft of the cable signal by freeloaders.

Description

BACKGROUND

In community antenna television distribution systems, (CATV) a primary or line cable carries radio and television signals from a source through communities for distribution to a plurality of subscribers. Conventional tap boxes are disposed in spaced relationship along the line cable. The tap boxes may be installed outdoors in overhead or underground lines where they are exposed to the environments of nature, or they may be installed in apartment complexes where they are easily accessible by virtually anyone. Droplines are taken from the tap boxes to individual homes and establishments. The tap boxes generally have a series of output receptacles to which the droplines may be connected.

When a subscriber moves, does not pay his bill, or for any other reason is disconnected from the CATV system, his dropline is threadedly removed from its output receptacle in the tap box. According to conventional practice, plug device with resistor means therein is then threadedly secured to that receptacle. The plug serves as load means to match impedance and balance the line.

Anyone intending to make an illegal tap may then remove a plug and connect a dropline to the receptacle so as to obtain the radio or television signal without paying for the service. A cable company will experience great difficulty and considerable expense in attempting to detect illegal taps in general; taps made by removing the plug device from an out-of-service receptacle and illegally coupling a dropline thereto are virtually impossible to detect except by direct visual inspection of the tap box itself.

In accordance with the present invention, illegal taps are prevented efficiently and inexpensively by the provision of a plug device for receptacles which are not easily removable except by a special keyed tool.

SUMMARY OF THE INVENTION

This invention relates to a novel plug device for use in radio and television frequency signal systems such as CATV systems.

An object of this invention is to provide plug means to close and seal a receptacle, and further to provide resistor means in the plug means to load a signal circuit and subsequently balance the characteristic impedance of the circuit.

Another object of this invention is to provide plug means which is installable and removable in a receptacle only by special tool means, thereby preventing illegal taps by freeloaders and any other tampering with the receptacle.

A further object is to provide plug means as described above which utilizes few basic parts, and which is relatively inexpensive to manufacture.

One of the unique features of this invention is that when installed in a receptacle, the hardened outer sleeve of the plug will rotate freely relative to the receptacle, so that attempts to remove the plug by hand will be futile.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a CATV installation showing a tap box in a line cable and showing a series of four receptacles, three of which have droplines connected thereto and one of which has a plug device secured thereto;

FIG. 2 is an enlarged perspective view of a plug device showing its principle parts exploded along a common centerline;

FIG. 3 is a greatly enlarged sectional view taken along the lines 3-3 of FIG. 1; and

FIGS. 4 and 5 are sectional perspective views of a plug device with an associate installation-removal tool.

DESCRIPTION OF PREFERRED EMBODIMENTS

Referring to FIG. 1, there is shown a tap box TB connected to a line cable L. Three droplines D, which are connected to receptacle R, lead from tap box TB to subscribers. The fourth, or lowermost receptacle R is closed and sealed by a plug device constructed in accordance with the present invention. Droplines D are defined as conventional coaxial cables of the type having center conductors surrounded by subsequent layers of dielectric, shield (outer conductor) and jacket. Connectors C are defined as conventional plug connectors which are commercially available, and which are properly secured to the droplines D.

Referring to FIGS. 2 and 3, the principle parts of a plug device include a hardened outer shell 2, a body member 4, a pliable sealing washer 6 and a commercially available load resistor 8. Shell 2, which is generally cylindrical, is made of electrically conductive metal such as steel. Shell 2 is hardened to prevent the shell from becoming damaged or dented, particularly by prospective freeloaders trying to remove the plug. Shell 2 has an open end 10 and a closed end 12. As shown in FIG. 3, the closed end 12 has a small longitudinal hole 14 therein, which hole 14 is disposed offcenter from the normal centerline of shell 2. Body member 4, which is generally cylindrical, is made of electrically conductive metal such as brass. The outside diameter of member 4 is slightly smaller than the inside diameter of shell 2. This allows shell 2 to rotate relative to body 4 when the parts are assembled. Member 4 has an open end 16 and a nearly closed end 18. The longitudinal passageway through member 4 includes an enlarged threaded section 20 which is adapted to be threaded onto a receptacle R. At the base of threaded section 20 is a smaller section 22 within which seal 6 is disposed. A much smaller passageway 24 runs from section 22 to a still smaller passageway 26. The diameter of passageway 24 approximates the outside diameter of a resistor 8, and the diameter of passageway 26 approximates the outside diameter of the resistor lead 9. Passageway 26 terminates in a small bellmouthed opening 28 in the closed end 18 of member 4. An annular groove 30 is formed into the peripheral surface of member 4. A small longitudinal cavity in the form of a hole 32 is provided at the closed end 18 of member 4. Hole 32 is disposed on the same circular centerline as hole 14 so that these holes will align themselves upon rotation of shell 2.

ASSEMBLY

Referring still to FIGS. 2 and 3, the parts are assembled such that resistor 8 is disposed and bottomed in its passageway 24 in body member 4. One lead 9 is soldered, crimped or otherwise mechanically and electrically secured in opening 28 of end 18. Seal 6 is inserted in place in section 22 of member 4. Shell 2 is then disposed in place around body member 4 whereafter a series of inwardly directed indents 34 are formed in shell 2 directly over annular groove 30 in body 4. As an optional alternative, a depressed annular ring may be formed into shell 2. Indents 34 serve to hold shell 2 onto body 4 and prevent its removal therefrom; and further serve to allow shell 2 to rotate freely with respect to the body member 4.

OPERATION

Referring to FIGS. 4 and 5, an assembled plug device is threadedly secured to a receptacle R with the aid of an application tool T. Tool T comprises a device with cylindrical shank means 36 which terminates in a cylindrical recessed end 38. A pin 40 is disposed to project from the base of recess 38 toward the end of shank 36. Pin 40 which is off center relative to the common centerline of shank 36, serves to align holes 14 and 32, as particularly shown in FIG. 5, so that the plug device may be installed or removed.

It should be noted that with a plug device installed, FIGS. 3 and 5, a signal circuit is carried from a contact C' of receptacle R, to resistor 8 via forward resistor lead 7. The circuit continues through resistor 8 to body member 4, and on to the outer surface of receptacle R.

It should also be noted that other keying means such as slots, plurality of holes, etc., may be formed into shell 2 and body 4 without departing from the scope of the invention. It should be further noted that other electronic loading circuits, such as diode circuits, can be utilized without departing from the scope of the invention. Also, thin resilient covers may be insertably snapped over shell 2 to hide hole 14 from easy view.

Having now disclosed the concept for a new and improved plug device with keyed outer shell means, the following claims are appended to define what is believed to be inventive.

Claims

I claim:

1. An electrical plug device comprising outer shell means, an internal body means within said shell means having load resistor means therein and sealing means, said outer shell means being freely rotatable relative to said body means, said body means being adapted to be threaded onto or removed from a counterpart receptacle by special tool means, said sealing means adapted to seal said plug onto a receptacle and prohibit the ingress of moisture thereinto.

2. An electrical plug device comprising outer shell means rotatably secured to internal body means, load resistor means and sealing means within said body means, said outer shell means having first hole means in the end thereof disposed to overlie second hole means in the end of said body means, said first and second hole means comprising key means for keying said outer shell means to said body means so that said plug device may be installed upon or removed from a receptacle only by special tool means.

3. In an electrical plug device including body means with resistor means therein, sealing means defined by pliable gasket means adapted to become compressed between said plug device and a counterpart receptacle when said plug device is installed thereon, and outer shell means fixed to said body means and adapted to rotate freely relative to said body whereby said plug device can only be removed by keyed tool means.

4. In an electrical plug device including body means with resistor means therein, sealing means defined by pliable gasket means adapted to become compressed between said plug device and a counterpart receptacle when said plug device is installed thereon, outer shell means fixed to said body means and adapted to rotate freely relative to said body, first hole means in said shell means and second hole means in said body means, said first and second hole means adapted to become aligned by the rotation of said shell means, and tool means adapted to engage said plug device and said first and second hole means thereby to install and remove said plug device.

5. In an electrical plug device including body means with resistor means therein, sealing means defined by pliable gasket means adapted to become compressed between said plug device and a counterpart receptacle when said plug device is installed thereon, outer shell means fixed to said body means and adapted to rotate relative to said body, first hole means in said shell means and second hole means in said body means, said first and second hole means disposed in offcenter longitudinal relationship relative to the common centerline of said plug device, said first and second hole means further adapted to become aligned by the rotation of said shell means, and tool means adapted to engage said plug device and said first and second hole means thereby to install and remove said plug device.

6. In an electrical plug device including body means with resistor means therein, sealing means defined by pliable gasket means adapted to become compressed between said plug device and a counterpart receptacle when said plug device is installed thereon, outer shell means fixed to said body means and adapted to rotate relative to said body means, first hole means in said shell means and second hole means in said body means, said first and second hole means disposed in offcenter longitudinal relationship relative to the common centerline of said plug device, said first and second hole means further adapted to become aligned by the rotation of said shell means, and tool means adapted to engage said plug device and said first and second hole means thereby to install and remove said plug device, said tool means including a shank portion with a circular recess in the end thereof and a pin in said recess, said pin disposed concentrically with said first and second hole means.