US 3364457 A
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Description (OCR text may contain errors)
Jan. 16, 1968 R. J. VEITH ETAL 3,364,45?
ELECTRICAL ADAPTER Filed May 13, 1966 2 Sheets-Sheet 1 w f ,/ZMTw/fw ATTORNEY Jan. 16, 1968 R. J. VEITH ETAL 3,364,457
ELECTRI CAL ADAPTER Filed May 13, 1966 2 Sheets-Sheet 2 INVENTORS ROBERT .L VE/TH RAYMOND C. W/LK/NSON CLAUDE C. MART/N Aff/.; QMLAGENT f ATTORNEY United States Patent iice 3,364,457 ELECTRICAL ADAPTER Robert J. Veith, Alexandria, Va., and Raymond C. Wilkinson and Claude C. Martin, Oxon Hill, Md., assignors to the United States of America as represented by the Secretary of the Navy Filed May 13, 1966, Ser. No. 551,181 4 Claims. (Cl. 339-143) The invention described herein may be manufactured and used by or for the Government of the United States of America for governmental purposes without the payment of any royalties thereon or therefor.
The present invention is directed to an electrical adapter which electrostatically shields a signal lead or center conductor of an electrical device, the center conductor of the adapter, and the center conductor of a coaxial cable with minimization of current leakage to the signal lead.
Heretofore, coaxial cables have been connected to the output of an ionization chamber by crude connectors. However, problems exist due to humidity, which permit an excessive electrical leak between the outer shell of connected thereto. Such an electrical leak due to weather the detector and the inner conductor of the shielded cable conditions creates a situation wherein such ionization chambers must be checked and calibrated in a controlled environment. Other problems develop from the manner in which the cable has been connected to the ionization detectors.
The electrical adapter of the present invention is adapted to connect a coaxial cable to an ionization chamber wherein the center pin of the ionization chamber connects 'to the center pin of the coaxial cable connector such that the center conductor of the coaxial cable is ccntinuously shielded over its entire length. The connector affords a connection wherein the outer conductive shell of the chamber is insulated from the outer conductor of the cable and is such that insulation exists between the outer shell of the chamber and the center conductor of the cable and the ionization chamber.
lt is therefore an object of the present invention to provide an electrical adapter which is suitable for connecting the center conductor of a coaxial cable to the center pin of an ionization detector wherein the signal lead is electrostatically shielded over its entire length.
Another object is to provide an electrical adapter in which the conductive shell of an ionization chamber is insulated from the outer conductor of a coaxial cable connected thereto.
Still another object is to provide an electrical adapter which provides minimum electrical leakage between the shell of the detector and the center conductor of the C- axial cable.
Yet another object is to provide an electrical connector which positively connects a coaxial cable to an ionization chamber such that the coaxial cable is held securely thereto and may be easily removed therefrom.
While still another object is to provide an electrical adapter which is suiciently light in weight and ruggedly constructed so as to withstand vibrational forces of a launch vehicle if launched into space.
The nature of this invention as well as other objects and advantages thereof will be readily apparent from consideration of the following specification relating to the annexed drawing, in which:
FIG. l is a cross-sectional view illustrating the relative parts thereof secured to an ionization chamber which is only partially shown, and,
FIGS. 2, 3, and 4 are cross-sectional views of modifications of the electrical adapter shown in FIG. 1.
The electrical adapter of the present invention iS adapted to connect a coaxial cable to an ionization cham- 3,364,457 Patented Jan. 16, 1968 ber such that the center pin of the ionization chamber is protected against electrical leakage between the center pin and the outer shell of the ionization chamber and the outer conductor of a coaxial cable. The electrical adapter is provided with a central conductor which is insulated from an outer conductor that connects with the shell of the ionization chamber. The electrical adapter and modiications thereof are so constructed that the outer conductor of the coaxial cable which is connected to the electrical adapter may or may not have a completed electrical contact with the outer shell of the detector. Thus, there may be an electrical break between the outer conductor of the coaxial cable and the outer shell of the ionization chamber.
Now referring to the drawings wherein like reference characters represent like parts throughout the speciication there is shown in FlG. l for illustrative purposes only, a cross-sectional view of an electrical adapter made in accordance with the present invention. The electrical adapter is described as having two end sections 11 and 12 one of which connect to a coaxial cable and the other of which connects to the outer shell of an ionization `chamber or to any other electrical device to which it is desired to be connected. The electrical adapter includes a cylindrical elongated electrical conductor 13 which extends axially through the connector and is provided with slotted end portions 14 and 15 each of which forms a female connection to receive a male pin-like conductor of an electrical conductor. As shown, the end portion 14 is of a lesser diameter than the end portion 15 and is provided with a chamfer 16 at the main body portion of larger diameter. A cylindrical sleeve of insulation 17 of any suitable matc rial such as KELP, which is an exceptionally stable, high temperature, nonllammable thermoplastic material (KELF is a polymer of triiiuoromonochloroethylene and is a trade name of the M. W. Kellogg Company). The insulation sleeve may be made of any other material which has excellent chemical resistance, high electrical resistance, and is exceptionally resistant to wetting by water or moisture from the atmosphere. The insulation sleeve surrounds the electrical conductor coaxial therewith and is of the same length thereof. The insulation sleeve is of the same wall thickness throughout the length thereof and follows the contour of the cylindrical conductor with a small spacing 1S between the slotted ends of the electrical conductor and the insulation sleeve to allow for outward movement of the slotted ends during insertion and removal of a conductive pin connected therewith. A cylindrical brass conductor 21 having an inner diameter at one end which is the same as the outer diameter of the small end of the insulated sleeve and a larger diameter end which surrounds a portion of the insulator sleeve having the greater diameter is provided with threads 22 on the outer end thereof which extend to a shoulder 23 formed by the portion of the conductor having the greater diameter. The threaded brass conductor is positioned around the insulated sleeve and swaged thereto by any suitable means which is illustrated by the indentations 24 in the outer surface of the brass conductor element. A cylindrical sleeve 25 of KEL-F tits about the larger portion of the threaded brass conductor with the inner end 25 thereof extending radially inwardly to the larger diameter portion of the insulator sleeve such that the inwardly extending portion is in axial alignment with the inner end of the brass conductor. A cylindrical .brass conductor 27 is secured around the outer insulator element 25 and secured thereto by swaging. An inner end 28 of the outer cylindrical conductor extends radially inward along the innermost end of the outer insulator 25 and the inward radially extending end 26 of the outer conductor is machined or milled along its inner surface to provide a spacing 29 between the insulator sleeve 17 and the innermost end of the outer conductor by a thin wall section 30 that extends axially from the radially inwardly extended portion of the outer brass conductor, the purpose of which will be explained later. The end portion 12 of the electrical adapter is provided with a cylindrical conductor 31 which is secured about the insulator sleeve 17 by swaging in which the conductor element 31 extends toward the end 11 and interts within the space 29 formed by the thin wall 30 of the cylindrical conductor element 27 on the end 11. The conducted element 31 on the end 12 has an outwardly extending flange portion 32, the end of which has an axially extended flange portion 33. A cylindrical electrical conductor coupling element 34 having threads on the inner surface thereof is positioned around the radially outwardly extended potron of the conductive element 31 and is provided with an inwardly radially extended flange portion 35 which abutts against the radially outwardly extended flange portion of the element 31. The threaded coupling portion is provided with four equally spaced apertures 36 therein which serve as outgassing ports and may be used for rotating the threaded coupling element by use of a spanner wrench to secure the element to a threaded section 37 of an ionization chamber. A center pin 38 of an ionization chamber is shown inserted into the split end portion of the center electrical conductor element to illustrate how the electrical conductor is secured to the ionization chamber 39.
In assembly of the electrical adapter, the various elements of the electrical adapter are machined and formed into their proper mechanical shapes. The insulator sleeve is positioned around the axially extending conductive elernent and then the screw-threaded conductive section is positioned over and secured to the end of the insulator sleeve. The outer insulating element is slid onto the inner insulated sleeve from the right end 12 and extended over the conductive element. Then the outer cylindrical conductive element of the end 11 is slid over the conductor sleeve of end 12 and swaged onto the outer insulator element 25. An electrical lug is then slid over the end 12 and placed onto and soldered to the innermost end of the outer conductor. The coupling element 34 having the threads on the inner surface thereof for end 12 of the adapter is then slid over the conductive sleeve 31 and the radially outward extending flange 32 thereon then the conductive sleeve 31 is slid over the insulator sleeve 17 such that the elongated cylindrical portion thereof extends through the coupling element 34 and is in electrical contact with the conductive element 27 on the end 11 of the adapter. The cylindrical element 31 of end 12 is then swaged to the cylindrical insulator sleeve 17. The cylindrical conductive sleeve element 31 then secures the coupling element onto the electrical connector.
As can be seen by the assembly illustrated in FIG. 1 the insulator sleeve extends the full length of the center axially extending conductor, the outermost insulator on the end 11 separates the threaded conductor from the outer cylindrical conductor such that there is no electrical connection between the threaded vbrass conductor element and the outermost cylindrical conductive element. The outer cylindrical conductive element on end 11 is in electrical contact with the cylindrical element of end 12 and completes an electrical connection with the shell of the ionization chamber through the coupling element which is screw-threaded onto the ionization chamber. Since at the end 12, the center electrical conductor is surrounded by the insulating sleeve with an additional air spa-ce between the insulator sleeve and the outermost conductor of the ionization chamber there is a very long path and high resistance between the outer conductor of the ionization chamber and the center pin thereof. The electrical lug 20 connected to the electrical connector may be used to supply a voltage source to the outer shell of the ionization chamber and the axial elongated conductor within the electrical adapter will connect the output from the center pin of the ionization chamber to a center conductor of a coaxial cable through the cylindrical conductive element within the electrical adapter. At the coaxial cable end, the coaxial cable connector outer conductor which is normally at ground potential guards the center pin from all current leakage from the Voltage on the shell of the ionization chamber.
FIG. 2 illustrates a modilication of the electrical adapter as shown in FIG. 1 and more specifically illustrates an adapter which rnay be used to connect the shell and the center pin conductor of an ionization chamber to a coaxial cable wherein the outer conductor of the coaxial cable is electrically connected to the shell of the ionization chamber. As shown, the electrical adapter includes the center conductor and an insulating sleeve surrounding the center conductor such as shown in the connector of FIG. l, with exception that the elements are much shorter. The conductor 41 having threads 22 on the outer end thereof is made as an integral part with a cylindrical conductive element 31 as shown on the end 12 of the brass connector of FIG. l wherein the radially outwardly extended end portion 42 serves as a shoulder against which the coupling element 34 holds the connector to the ionization chamber. Thus, the insulating sleeve insulates the center conductor from the outer conductor which is formed by the outer threaded brass cylindrical element and the conductive co-upling which secures against the shoulder on the brass conductive element. Thus, the center wire conductor of a coaxial cable will be connected electrically to the center pin of an ionization chamber through the axial conductor whereas the outer conductor of a coaxial cable connects with the shell of the ionization chamber through the threaded brass connector 41 and the coupling 34.
FIGS. 3 and 4 are directed to electrical adapters which adapt the use of various electrical connectors manufactured by Microdot Incorporated, South Pasadena, California to Iuse as described for FIGS. l and 2. FlG. 3 is an adapter suitable for connecting a microdot connector number 051-0252 to an ionization chamber whereas FIG. 4 is an adapter suitable for connecting a microdot connector number 31-56 and microdot connector .3S-61 to an ionization chamber. As shown by illustration in FIG. 3 the microdot connector 4@ is modified to include a split end connector 43 which connects with the center conductor through the microdot connector. An internally threaded conductive cylindrical sleeve 44 having a radially outwardly extending surface 45 at one end thereof is screw-threaded onto the microdot connector. The cylindrical sleeve includes spaced drill holes 46 axially in the end thereof for the purpose of using a Spanner wrench for threading the cylindrical sleeve onto the microdot connector. A cylindrical coupling element 34 having an inwardly radially extending lange 35 thereon which ts against the radially outwardly extending portion of the cylindrical conductive member is in electrical contact therewith when the coupling is screwed into place. An insulating element 48 having a screw-thread on the outer surface of one end thereof and a much larger diameter head surface with a cylindrical passage 49 axially therethrough is screw-threaded onto the inner threads of the cylindrical conductive member such that the head portion of the insulator will surround the split-end center conductor to provide insulation between the cylindrical conductive member connected to the outer surface of the microdot connector and the inner split-end conductor which is connected to the inner conductor of the microdot connector. The `head portion of the insulator element is of less diameter than the coupling s-uch that the threaded end of the ionization chamber to which the coupling elernent is threaded will pass between the outer surface of the insulator element and the screw-threaded inner surface of the coupling element. The insulator element is also provided with drill holes 46 axially drilled into the end surface thereof for the purpose of using a Spanner wrench for screw-threading the insulator element into the cylindrical conductive element. The adapter illustrated in ase-4,457
FIG. 3 completes an electrical circuit between the outer surface of the microdot connector and the shell surface of the ionization chamber thro-ugh the cylindrical elec* trical conductive member ed and tue coupling member 34 which is in contact therewith when screwed in place.
The cylindrical conductive coupling element 34 is provided with a threaded hole 52 therethrough such that a locltscrew 53 may be screwed into the threaded hole in the coupling element, to provide a lock between the coupling element and the radially outwardly extending surface of the cylindrical conductive sleeve 44.
FIG. 4 is similar to the adapter described in FIG. 3; however, an insulator element is provided between the coupling member and the outer conductive surface of the microdot connector such that an electrical path is broken between the outer surface of the microdot connector and the outer shell surface of the ionization chamber. In the adapter as shown in FlG. 4, an insulating element :'55 is assembled between the outer conductive surface of the microdot connector and the coupling member and is locked in place as shown for FG. 3.
The central cylindrical electrical conductive element is separated from the coupling element by a portion of the insulator which extends between the coupling element and the electrically conductive element. A cylindrical insulator sleeve 57 of KEL-F or other similar insulator material is screw-threaded to the threads on the inner surface of the electrical conductive element to provide insulation between the split conductor i3 of the central electrical conductor and the cylindrical conductive element threaded onto the microdot connector.
The adapters of FIGS. 3 and 4 illustrate different electrical connectors which may be used to connect a coaxial cable directly to the center pin and the outer shell of an ionization chamber or to connect only the center pin to the ionization chamber.
It can be seen from the electrical adapter illustrated by FIGS. 1 through 4 that a coaxial cable may be connected to an electrical connector such that only the center conductor is used to conduct an electrical current or either both the outer conductor and the inner conductor of the coaxial cable may be used to conduct an electrical current from a desired element. In either of the modications shown, the center conductor is separated from the outer conductor by an insulating member which extends around the center conductor to minimize electrical current to pass on the surface of insulators between the outer conductor of the adapter and the center conductor or between the center conductor and the shell of the ionization chamber to which it is connected.
The electrical adapter as described in the specification above has been indicated as useful to connect a microdot connector to which a coaxial cable is connected to an ionization chamber. lt will be obvious to those skilled in the art that the electrical adapter may be used for other purposes or other equipment insofar as the other equipment maires use of a center pin conductor and an outer screw-threaded conductor onto which the coupling is screw-threaded. These adapters may also be made in various sizes for connecting different types of equipment. For instance, the particular adapter as shown in FIG. 1, in actual use for connecting instrumentation in a satellite, is only about an inch and a half length and about 3/s of an inch in diameter. Obviously the connectors maybe made larger, if desired, insofar as the structure is concerned; however, it is important that the insulative qualities of the connector be maintained relative to the various conductive elements.
Obviously many modifications and variations of the present invention are possible in the light of the above teachings. It is therefore to be understood that within the scope of the appended claims the invention may be practiced otherwise than as specifically described.
What is claimed and desired to be secured by Letters Patent of the United States is:
It. An electrical adapter for connecting a coaxial cable connector to an ionization chamber which comprises:
an axially disposed electrically conductive linear electrode extending the length of said electrical adapter,
said axially disposed conductive electrode having a female connection at eac-h end thereof,
a first insulator,
said first insulator secured about said axially disposed electrode along the entire length thereof,
a first electrically conductive element secured about one end of said rst insulator element,
said first electrically conductive element having screwthreads on the outer end thereof,
a second insulator surrounds the Unthreaded portion of said rst conductive element and electrically enclosing the inner end thereof,
a second conductive element,
said second conductive element surrounds said rst insulator in axial alignment with said first conductive element and separated therefrom by said second insulator element,
said second conductive element extending along said first insulator over a portion thereof and having a radially outwardly extending portion at one end thereof,
said radially outward extending portion providing a shoulder,
said coupling surrounding said radially outward extending portion of said second conductive element and extending axially along the length of said connector,
said coupling including an inwardly extending flange that secures against the shoulder provided by said radially outward extending portion of said second electrically conductive element,
said coupling including screw-threads on the inner surface thereof for threading onto a threaded portion of an ionization chamber, and
a third electrically conductive element,
said third electrically conductive element surrounding said second insulator element extending along substantially the length thereof and extending over the inner end thereof. 2. An electrical connector as claimed in claim 1, wheresaid coupling element includes apertures therein for receiving a Spanner wrench for rotation of said coupling.
3. An electrical connector as claimed in claim 2, which includes:
an electrical Contact element secured to said third electrically cond-uctive element to provide means to which a voltage source may be connected.
4. An electrical connector as claimed in claim 2, wheresaid rst and second electrical elements are made as one single element to complete an electrical circuit between said threaded end of said rst electrically conductive element and said coupling.
References Cited UNITED STATES PATENTS 5/1963 Fclts 339--75 5/1965 Atkins 339-177