US2706282A - Tap for coaxial cable transmission lines - Google Patents

Description

April 12, 1955 D. DUDRA 2,706,282

TAP FOR COAXIAL CABLE TRANSMISSION LINES Filed March 22, 1954 Tlzrl 4i. 2

/N VE N TOR DAN/E L 'DUDRA mazzzwg A TTORN'FV Unitcd States Patent TAP FOR COAXIAL CABLE TRANSMISSION LINES Daniel Dudra, Kulpmont, Pa. Application March 22, 1954, Serial No. 417,739 Claims. (Cl. 339-97) This invention relates to the art of taps for electrical conductors, and, more particularly, to a novel and improved tap which is particularly adapted for use on coaxial cable transmission lines.

While there have been numerous attempts in the past to provide satisfactory taps for electrical conductors of one sort or another, so far as I am aware, there have been but few developments along the lines of a tap which may be efiiciently used on coaxial cable transmission lines.

Accordingly, it is among the objectives of the present invention to provide an electrical tap which may be used on coaxial cable transmission lines with high efficiency.

Another object is the provision of a device of the class described which may be quickly and easily attached, yet durable in service.

Another object is to provide a device which, while possessed of the foregoing advantages, may be easily and inexpensively manufactured.

The invention, then, comprises the features hereinafter fully described and as particularly pointed out in the claims, the following description setting forth in detail certain illustrative embodiments of the inventiori, these being indicative of but one of a number of ways in which the principles of the invention may be employed.

In said drawings:

Figure 1 is a longitudinal sectional view of a device which has been made in accordance with the teachings of the present invention, the same being shown as applied to a standard form of coaxial transmission cable;

Figure 2 is an end view taken from the left-hand end of Figure 1;

Figure 3 is an exploded longitudinal view of the elements of the device of Figure l; and

Figure 4 is a view which is generally similar to Figure 3, but showing the various elements thereof in end elevation.

Referring more particularly to the drawings, the letter A designates the center conductor of a conventional coaxial cable transmission line, the same also comprising a relative thick surrounding layer B of plastic insulation, such as of the Teflon or Styrene variety. This plastic insulation B is covered by a metallic electrically conductive ground braid C which is, in turn, covered by an outside layer D of standard insulating material, such as rubber.

At the left-hand end of Figure 1, there is illustrated a coaxial cable transmission tap-01f line which is composed of elements a, b, c, and d which correspond to the aforementioned elements A, B, C, and D, respectively, of the larger coaxial cable, but are considerably smaller in SlZC.

According to the teachings of the present invention, there is provided a generally tubular main body member 2, one end of which is externally screw-threaded, as at 4. This externally screw-threaded main body member 2 is provided with a slot 6, the side walls of which are straight, and the distance between them sutiicient to accommodate the larger coaxial transmission cable. The bottom of this slot 6 is curved, as at 8, in such manner as to form a seat for the larger coaxial cable.

The opposite end of the generally tubular main body member 2 is provided with a bore 10 which is screwthreaded, as at 12; and this bore 10 communicates through a smaller cylindrical bore 14 with a cylindrical chamber 16.

The outer end of the cylindrical chamber 16 opens onto the curved bottom 8 of the cable-receiving slot 6, while its inner end connects with the bore 10 through a bevelled portion 18. i

The cylindrical chamber 16 is adapted to receive a cartridge 20 of similar size and shape which is composed of plastic insulating material (which, again, may be of the Teflon or Styrene variety). Disposed within the cartridge 20 is a small cylindrical resistor 22 which is provided with an elongate slot 6 for a distance which is approximately the same as the radius of the large coaxial cable. This elongate projecting pin 24 carries a sleeve 25 of suitable plastic insulating material, such as Teflon.

The outer end 26 of the projecting pin 24 is of arrow shape and the rearward portion thereof forms a shoulder 28 against which the outer end of the sleeve 25 seats.

The other end of the resistor 22 is provided with a minute centrally disposed recess (not shown) for receiving the end of the central conductor wire a of the smaller coaxial cable which is illustrated at the left of Figure 1. This minute centrally disposed recess in the inner end of the resistor 22 communicates with the small cylindrical bore 10 (in the main body member 2) through a small opening 30 in the center of the rearward end wall of the cartridge 20.

An exteriorly threaded ferrule 32 is received in the bore 10 in screw-threaded engagement with the threads 12 thereof; and the outer end of this ferrule (32) is provided with a wrench-receiving head 34 which is adapted to seat against the adjacent end of the main body member 2.

A block 36 is disposed in the slot 6 in the main body member 2; and its inner end is concaved, as at 38, in the manner of the cable-contacting bottom 8 of said s ot.

This concaved inner end 38 of the block 36 is provided with a pair of pointed pins 40 which project sufiiciently to enable them to penetrate the outer insulation D of the large coaxial cable and make electrical contact with the metallic electrically-conductive ground braid C.

The block 36 is forced against the large coaxial cable by means of a cap 42 which screw-threadedly engages the threaded portion 4 of the main body portion 2.

As previously mentioned, the block 36 (which carries the pins 40) is forced against the large coaxial cable by means of the screw-threaded engagement of the cap 42 with the main body portion 2 of the tap of the present invention. It will, of course, be understood that this movement of the block 36 toward the large coaxial cable will be accompanied by the movement of the large coaxial cable onto, and over, the elongate projecting pin 24 which is carried by the cartridge 20.

With the cartridge 20 and its interiory disposed resistor seated in the cylindrical chamber 16, the outer insulation d of the smaller coaxial cable is peeled back a distance but slightly greater than the length of the small cy.indrical bore 14; and the metallic electrically-conductive ground braid c is laid bare for a small distance (say, of an inch). This ground braid c of the smaller coaxial cable is pushed back from the insulation b and over it a washer 44 is placed. These parts are then fitted in to the bore 10 which permits the projecting end of the central conductor wire a to extend through the small central opening in the rearward end wall of the cartridge 20 and to seat in the minute centrally disposed recess (not shown) in the back of the resistor 22.

The ferrule 32 is then inserted and its inner end forces the washer 44 to firmly hold the ground braid c against the bottom of the bore 10 of the main body member 2.

In the foregoing manner, there is provided an excellent connection for the ground braid c of the smaller coaxial cable through the main body member 2 and its block 36 and pointed pins 40 to the ground braid C of the larger coaxial cable.

The arrow-shaped end 26 of the projecting pin 24 of the resistor 22 enters the central conductor wire A of the large coaxial cable to make firm electrical contact therewith.

The plastic insulating B, under pressure, flows around the projecting pin 24 from the shoulder 28 of the arrowshaped end 26 rearwardly to its point of connection with the resistor 22. In this manner, the projecting pin 24 is effectively insulated from the ground braid C.

According to the foregoing construction and arrangement, there is provided a device which attains all of the objectives set forth hereinbefore; and one which is also waterproof.

While I have shown and described certain specific embodiments of the present invention, it will be readily understood by those skilled in the art that I do not wish to be limited exactly thereto, since various modifications may be made without departing from the scope of the invention as defined in the appended claims.

I claim:

1. A tap for transferring electrical energy from along the length of a coaxial transmission cable of the type comprising a central conductor and a radially disposed concentric ground conductor; said tap comprising a generally tubular electrically conductive member having a transverse recess which receives a peripheral portion of said cable, a pin disposed in said recess and in insulated relationship with respect to said first-named member, said pin penetrating said cable to the extent of making electrical contact with its central conductor but not its concentrically disposed ground conductor, a second member screw-threadedly engaging said first-named member, a pin carried by said second-named member and penetrating said cable to the extent of making electrical contact only with its aforementioned ground conductor, said pin being in electrical contact with said first-named member, a third member, said third member being in screw-threaded engagement with said first-named member, and a coaxial cable transmission tap-off cable comprising a central conductor and a radially disposed concentric ground conductor, said coaxial transmission tap-off cable having one of its ends disposed in said third-named member, the central conductor of said coaxial transmission tap off cable being in electrical contact with said first-named pin, the ground conductor of said coaxial transmission tapolf cable being in electrical contact with said first-named member.

2. A tap for transferring electrical energy from along the length of a coaxial transmission cable of the type comprising a central conductor and a radially disposed concentric ground conductor; said tap comprising a generally tubular electrically conductive member having a transverse recess which receives a peripheral portion of said cable, a pin disposed in said recess and in insulated relationship with respect to said first-named member, said pin penetrating said cable to the extent of making electrical contact with its central conductor but not its concentrically disposed ground conductor, a second electrically conductive member screw-threadedly engaging said first-named member, a pin carried by said secondnamed member and penetrating said cable to the extent of making electrical contact only with its aforementioned ground conductor, a third member, said third member being in screw-threaded engagement with said first-named member, and a coaxial transmission tap-off cable comprising a central conductor and a radially disposed concentric ground conductor, said coaxial transmission tapolf cable having one of its ends disposed in said thirdnamed member, the central conductor of said coaxial transmission tap-off cable being in electrical contact with said first-named pin, the ground conductor of said coaxial transmission tap-oif cable being in electrical contact with said first-named member.

3. A tap for transferring electrical energy from along the length of a coaxial transmission cable of the type comprising a central conductor and a radially disposed concentric ground conductor; said tap comprising a generally tubular electrically conductive member having a transverse recess which receives a peripheral portion of said cable, a pin disposed in said recess and in insulated relationship with respect to said first-named member, said pin penetrating said cable to the extent of making electrical contact with its central conductor but not its concentrically disposed ground conductor, a second electrically conductive member screw-threadedly engaging said first-named member, a pin carried by said secondnamed member a'ndpenetrating said cable to the extent of making electrical contact only with its aforementioned ground conductor, a third electrically conductive member, said third electrically conductive member being in screw-threaded engagement with said first-named member, and a coaxial transmission tap-off cable comprising a central conductor and a radially disposed concentric ground conductor, said cdaxial transmission tap-off cable having one of its ends disposed in said third-named member, the central conductor of said coaxial transmission tap-off cable being in electrical contact with said firstnarned pin, the ground conductor of said coaxial transmission tap-off cable being in electrical contact with said first-named member and said third-named member.

4. A tap for transferring electrical energy from along the length of a coaxial transmission cable of the type comprising a central conductor and a radially disposed concentric ground conductor; said tap comprising a generally tubular electrically conductive member having a transverse recess which receives a peripheral portion of said cable, a pin disposed in said recess and in insulated relationship with respect to said first-named member, said pin penetrating said cable to the extent of making electrical contact with its central conductor but not its concentrically disposed ground conductor, a second electrically conductive member screW-threadedly engaging said first-named member, a pin carried by said secondnamed member and penetrating said cable to the extent of making electrical contact only with its aforementioned ground conductor, a third electrically conductive member, said third electrically conductive member being in screw-threaded engagement with said first-named member, and a coaxial transmission tap-off cable comprising a central conductor and a radially disposed concentric ground conductor, said coaxial transmission tap-off cable having one of its ends disposed in said third-named member, the central conductor of said coaxial transmission tap-off cable being in electrical contact with said firstnamed pin, a portion of the ground conductor of said coaxial transmission tap-off cable being clamped between said first-named member and said third-named member.

5. A tap for transferring electrical energy from along the length of a coaxial transmission cable of the type comprising a central conductor and a radially disposed concentric ground conductor; said tap comprising a generally tubular electrically conductive member having a transverse recess which receives a peripheral portion of said cable, a pin disposed in said recess and in insulated relationship with respect to said first-named member, said pin penetrating said cable to the extent of making electrical contact with its central conductor but not its concentrically disposed ground conductor, an electrically conductive block disposed in said recess, a second electrically conductive memberscrew-threadedly engaging said firstnamed member and serving to force said block against said cable, a pin carried by said block and penetrating said cable to the extent of making electrical contact only with its aforementioned ground conductor, a third electrically conductive member, said third electrically conductive member being in screw-threaded engagement with said first-named member, and a coaxial transmission tapoff cable comprising a central conductor and a radially disposed concentric ground conductor, said coaxial trans! mission tap-off cable having one of its ends disposed in said third-named member, the central conductor of said coaxial transmission tap-off cable being in electrical contact with said first-named pin, a portion of the ground conductor of said coaxial transmission tap-off cable being clamped between said first-named member and said thirdnamed member.

References Cited in the file of this patent UNITED STATES PATENTS 2,196,964 Let: Apr. 9, 1940 2,203,337 Mebold June 4, 1940 2,511,524 Adler June 14, 1950 2,615,948 Kamen Oct. 28, 1952 2,677,108 Brady Apr. 27, 1954 FOREIGN PATENTS 455,196 Great Britain Oct. 15, 1936

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