Precision test connector

Abstract: An electrical precision test connector (1) comprises an electrical conductor (2) with conductive end portions (34) and (40) a hollow, bipartite shell (3) and a dielectric insert (4) as part of the conductor (2). The electrical conductor (2) further comprises a flexible, slotted contact end portion (24) with flat, opposing contact surfaces (36 and 37) with the slotted end portion being pinched (38) for a slideable, clamping engagement, above and below, with an inserted tab connector and the hollow, bipartite shell (3) having an end contact surface (24) and being spring biased to provide complete electrical contact with a corresponding portion of a test unit (54) during connection.

Description: This invention relates to an electrical precision test connector assembly for disconnect connection to the tab lead of a ferrite component such as a circulator or isolator. A precision test connector is utilized in the testing of a ferrite component, such as a circulator or isolator, operating at microwave frequencies and having thin and narrow tab leads. Exacting standards of performance are set for these components. Circulators and isolators provide nonreciprocal transmission paths, i.e. microwave energy may travel the transmission path in one direction with little loss but will be greatly absorbed when applied from the opposite direction. The nonreciprocal action provides useful benefits, and circulators are commonly used as duplexes in connection with a transmitter, antenna and receiver, as coupling elements in reflection amplifiers, such as parametic amplifiers and tunnel-diode amplifiers, or in conjunction with bandpass filters. Isolators are used between transmitter and antenna in communications and radar systems to eliminate energy reflected from the load back to the source. Resonance isolators are used as interstage isolators to minimize reflections between circuit elements. The present invention is applicable to ferrite components, such as circulators and isolators, which are microminiature ferrite devices having input and output tab leads whereby the components are assembled onto a printed circuit board and the tab leads are soldered to form connections thereto. The tab leads are extensions of the circulator and isolator center conductors. The tab leads may be made of gold plated beryllium cooper. The tab leads provide optimum contact with the circuit board and tension free, solder joints. In testing ferrite components with tab leads, the ferrite component is connected by solder to a single trace micro strip transmission test fixture and then to a testing unit such as an automatic vector network analyzer, for the purpose of testing for return and insertion loss to determine reflection coefficient. Connecting the testing unit and the ferrite components is time consuming. Further, the tab lead itself is fragile and may be damaged by soldering to the test fixture. Indeed, manufacturers recommend that customers test the circulator or isolator components only if there is an unusual need for precise measurement of performance prior to actual use. Another problem associated with the testing of such components includes maintaining a complete, firm and reproducible electrical contact between the tab lead of the component and the testing unit. Results obtained during one testing must be reproducible. Reproducibility depends, to a great degree, on consistent, nonvarying electrical contact between the tab lead and the testing unit. Further, test data obtained by performing the test must be nonvarying while the test is being conducted over a time interval. Repeated tests must produce consistent test data to assure that the ferrite component will operate according to desired standards. Reproducibility of test data taken over periods of time is affected by the reliability of the precision test connector that connects the ferrite component to the testing unit. Known test connectors include US-A-3,627,929 disclosing a distribution frame of a telephone exchange having a break jack assembly for disconnect cross connection and for connection to a test plug unit. The assembly has contact springs with rectilinear portions to provide flat contact surfaces. The flat contact surfaces are urged into contact with a plug member of a test plug unit. US-A-4 734 651 discloses a device for testing for electrical continuity and short circuits between terminals of a multicontact electrical connector and conductive cores of electrical leads. US-A-4 441 781 relates to a method for terminating coaxial cable and discloses a connector having a front shell, a rear shell, a dielectric insert,a center contact, a coupling and a locking ring. US-A-4 580 862 discloses spring biased, float mounted connectors for coaxial cables. There is disclosed herein an electrical precision test connector assembly for interconnecting a testing unit with a component which is to be tested for electrical continuity, reflection coefficient or the like. The test assembly maintains a complete, firm and reproducible electrical contact between the tab lead of the component and the testing unit and provides improved reproducibility of the electrical contact between tab lead of the component and the testing unit by polarization of an electrical conductor within the connector shell, the connector shell being capable of orientation of an end contact surface at 90 degree intervals. The improvement to the electrical conductor assures a precise polarized alignment of the conductor within the shell, and an improved front face of the shell provides precise polar alignment of the connecting end face of the connector shell to a test unit. One object of this invention is to provide a connector with a consistent, nonvarying contact to assure accurate and reproducible results. Another object of the invention is to provide such a connector that will assure accurate and reproducible results over an extended period of time and after repeated usage. another object is to provide a device that may be connected repeatedly to tab leads without the need for soldering, and that establishes a reliable and complete connection without damaging the tab leads. The test connector assembly disclosed herein accomplishes these objectives and comprises an electrical conductor with conductive end portions and a hollow shell encircling the center electrical conductor. The electrical conductor comprises a flexible, slotted contact end portion with flat, opposing, electrical contact surfaces. The end portion is closed at one end for slideable, clamping engagement with an inserted tab connector to thereby maintain flat, biased, electrical contact, above and below, with a portion of a tab lead. The electrical conductor, further, is recessed at the opposite end portion for connection with a corresponding electrical conducting unit. The hollow shell has a rear contact surface encircling the slotted contact end portion of the conductor and an outer body with a partial overlap portion and flange portion to define a groove between the bodies. The test connector assembly further comprises spring means positioned against the shell and biasing the shell into complete annular electrical contact of the circular contact surface with the complementary body of the component which is to be tested. The present consists in an assembly in combination with a fixed plate as defined in claim 1. US-A- discloses an assembly in combination with a fixed plate according to the preamble of claim 1. For a better understanding of the invention, reference will now be made, by way of example, to the accompanying drawings. Figure 1A is a side sectional view of an electrical precision test connector assembly which is a preferred embodiment of the present invention. Figure 1B is a rear elevation view of the device of Figure 1A taken along lines 1B-1B of Figure 1A. Figure 1C is a perspective view of portions of the tab lead in slotted contact end portion of the connector. Figure 2A is a side sectional view of the electrical precision test connector with rear hollow body rotated 90 degrees from the orientation of the rear hollow body as shown in Figure 1A and as hereinafter described. Figure 2B is a rear elevation view of the device of figure 2A taken along lines 2B-2B of Figure 2A. Figure 3A is a side sectional view of the electrical precision test connector of Figure 2A with bipartite shell extracted from a fixed plate, while Figure 2A shows the bipartite shell loaded within the square port of the fixed plate as hereinafter described. Figure 3B is a perspective view of a portion of the bipartite shell and fixed plate of Figure 3A showing the bipartite shell being extracted from the port of the plate. Figure 3C is a perspective view of the same portion of bipartite shell and fixed plate as shown in Figure 3B but is an illustration of rotating the shell 90 degrees and reinserting the shell into the port of the plate. Figure 4 is a fragmented perspective view of the electrical connector assembly shown in Figure 1A. With reference to Figures 1, 2, and 3, each electrical precision test connector assembly 1 includes an electrical conductor 2, a hollow, bipartite, conductive shell 3, annular dielectric insert 4, retaining ring 5 and spring 6. Also shown is mounting member 7, which has a cup-shaped portion 10 encompassing, substantially, front outer body 8 and rear hollow jack body 9 of the bipartite shell 3 and a flange portion 11 with holes 12 and 13 to accommodate fasteners 48', such as bolts, for mounting the test connector assembly 1 to fixed plate 56 having port 58 for accepting a portion of jack body 9 as hereinafter described. The hollow bipartite shell comprises threaded front outer body 8 and rear hollow jack body 9. Front body 8 has stepped bore 14 extending therethrough including recess 15, inwardly flanged 16, to accept a corresponding connection of a conventional coaxial cable connector (not shown), center barrel section 17 and rear section 18 having bore of greater diameter than that of the barrel section 17. Front outer body 8 has three cylindrical portions 49, 50 and 51 of different outer and inner circumference, and outward threaded portion 52 for threadable connection with a testing unit such as an automatic network analyzer. Cylindrical portions 49 and 50 form outer flange 45, and portions 50 and 51 form inner flange 16. Front body 8 has inward threads 20 on its inside rear wall 53. Body 8 terminates in annular face 21. Hollow bipartite body 3 further includes rear hollow body 9 with uniform core 22 with threading 23 for insertion into front body 8 and connection with corresponding threading 20 of front body 8, end contact surface 24 and forward annular end 25. Toward the front of rear hollow body 9 are polarizing slots 27A located at 180 degrees around the annular profile of body 9. End contact surface 24 is substantially square in profile with removed corners to thereby form an octagonal profile with four edges 59 equal to one another and four other edges 60 equal to each other. Further, the rear of body 9 at the octagonal profile is characterized by opposing flutes 61 which serve as identification marks signifying the particular orientation of bipartite shell as loaded within port 58 of fixed plate 56 as hereinafter described. The conductor 2 has enlarged annular waist comprising an annular dielectric insert 4 with bore 28, round in shape, but with flatted sides 42 for securing electrical conductor 2 into fixed position. Insert 4 is a one piece body having an outer ring structure 26 with nubs 27 for fit into complementary slots 27A of rear hollow body 9. Insert 4 is characterized by outer bead 29 and inner bead 30 forming annular recess 31 and annular recess 32. Electrical conductor 2 consists of insert 4 and substantially barrel-shaped bipartite body 33 of portions 34 and 40. Portion 34 is a solid end section characterized by a precisely machined slot 35 for slideable engagement with the inserted input or output tab lead 55 of a ferrite component 54, such as a circulator, which is to be evaluated to determine return loss, insertion loss for reflection coefficient and the like. As shown, the electrical conductor 2 comprises a resilient spring, slotted contact end portion 34 with flat, opposing contact surfaces 36 and 37. End part 34 is biased into a closed position when not engaged with the tab lead of a ferrite component. The nose 38 of slotted portion 34 may be beveled to provide a flared entry for the tab lead 55 of the circulator 54. Portion 34 further includes narrow waist section 39 for fitting within the bore 28 of annular dielectric insert 4 to form annular waist with nubs 27 and outward threads 43 for interconnection with inner threads (not shown) of portion 40 to form bipartite body 33. Waist section 39 is particularly characterized by flats 42 which fit to complementary flatted sides 42A within bore 28 of annular dielectric insert 4 to prevent rotation of the bipartite body 33 relative to the insert 4. The adapter portion 40 of electrical conductor 2 has a clamping type connector 41. Within the bore 47 of adapter portion 40 are inner threads (not shown) for interconnection with the outward threads 43 of portion 34. Cup-shaped portion 10 of mounting member 7 is inward-lipped to form annular flange 44. Corresponding, front outer body 8 of the hollow bipartite shell 3 has an outer flange 45 formed by cylindrical portions 49 and 50 which, in conjunction with flange 44 of the mounting member 7, define an annular recess 46 circumferential to the barrel of portion 34 of shell 3. Spring means 6, shown as a coil spring, is positioned within the annular recess 46 with one end biased against the outward flange 45 of front outer body 8 and one end biased against the inward flange 44 of part 9 into complete electrical contact with complementary surface 48 of a testing unit or ferrite component 54 with tabs 55 inserted into slot 35 of conductor 2. Shown also is fixed plate 56 for providing a mounting for the electrical test connector 1. Fixed plate 56 has mounting holes 57 and port 58. Port 58 is in two sections having a smaller rear portion 62 substantially square shaped in profile and an enlarged forward portion 63. In constructing the test connector 1, portions 34 and 40 are threaded together with waist section 39 residing within bore 28 of insert 4, flats 42 flush to flats 42A. The conductor 2, including insert 4, is fitted within central barrel section 17 of front body 8 and core 22 of rear body 9 with nubs 27 of insert 4 fitted to complementary slots 27A. The combination of the fit of nubs 27 to slots 27A and flat surfaces 42 of portion 34 to the flats 42A within bore 28 of insert 4 retain the conductor 2 polarized within the bipartite shell 3 preventing relative rotation of the bipartite body 34. Spring 6 is fitted circumferentially to the combination of the bipartite shell 3 with conductor 2 and these parts are loaded into the cup-shaped portion 10 of mounting member 7 with spring 6 biased within annular recess 46. Retaining ring 5 is fitted to the rear hollow jack body 9 of conductor 2. The precision test connector 1 is then secured to fixed plate 56 by means of fasteners 48' through mounting holes 12 and 13 of flange portion 11 to mounting holes 57 of the plate 56 with end contact surface 24 of jack body 9 disposed therethrough port 58. In operation, the electrical precision test connector 1 is attached to a testing unit, such as an automatic vector network analyzer, usually by mating with a plug of the analyzer into the recess 41 of the clamping portion 40 of the conductor 2. Thereafter, and one-by-one, the ferrite components, such as circulators, having tab leads 55, are connected to electrical test connector 1 by inserting lead 55 within spring biased, slotted contact end portion 34 to form a slideable, clamping engagement both above and below the lead 55. Spring means 6 urges end contact surface 24 forward and against the body 48 of the circulator so that forward annular end 24 abuts the body 48 of the circulator to provide a conductive electrical contact between the body 48 of the circulator and the hollow shell 9 of the test connector 1. The circulator is tested while contact surfaces 36 and 37 maintain flat, biased electrical contact above and below a portion of the tab lead 55. Upon completion of testing, the lead 55 is withdrawn and the tab lead 55 of another circulator is connected for testing. In Figures 2A and 2B, the precision test connector 1 is shown loaded within port 58 of fixed plate 56. The flat sides 59 of end contact surface 24 fit to the flat sides 59A of the port 58 preventing relative movement and providing a fixed profile to enhance the fit of tab 55 of test unit 54 to slot 35 of conductor 2 for improved testing. Then, with reference to Figures 3A through 3C, the conductor 2 and shell 3 may be withdrawn from rear portion 62 of port 58 against the bias of spring 6 into the annular bore-shaped forward portion 63 of port 58, (Figures 3A and 3B), rotated 90 degrees and reloaded within the square rear portion 62 for testing of a circulator or the like at a 90 degree orientation from that of the first testing.

Claims: An electrical precision test connector assembly in combination with a fixed plate (56) having a port (58) with flat sides (59A), for testing an electrical component, the connector assembly comprising, an electrical conductor (2) and a conductive shell (3) encircling the conductor (2), a slotted end (34) of the conductor (2) having opposed contact surfaces (36,37) for slidable assembly with and pinched engagement on opposites sides of a lead (55) of the component, there being a shell contact surface (24) on an end of the shell (3), wherein a spring (6) biases the shell contact surface (24) against the electrical component to establish an electrical connection; characterised in that said opposed surfaces (36,37) are flat for engaging opposite sides of a tab lead (55) of the electrical component, and the shell contact surface (24) has a precisely machined, non-circular outer profile presenting flat sides (59) to fit the flat sides (59A) of the port (58) to prevent movement of the connector assembly transversely of the biasing direction. An electrical precision test connector assembly as recited in claim 1, characterised in that the slotted end (34) is a solid end section with a machined slot (35). An electrical precision test connector assembly as claimed in claim 1 or 2, characterised in that a dielectric insert (4) encircling portions of the conductor (2) has a ring (26) fitted into the shell (3). An electrical precision test connector assembly as claimed in any claim 1, 2 or 3, characterised in that the slotted end (34) is biased closed. An electrical precision test connector assembly as claimed in any one of the preceding claims, characterised in that a dielectric insert (4) is encircled by portions (34,40) of the conductor (2) and the shell (3).

Inventors: COUPER WILLIAM DEAN, MICHAEL GEORGE WILSON, COUPER, WILLIAM DEAN, MICHAEL, GEORGE WILSON
Applicants: WHITAKER CORP, THE WHITAKER CORPORATION
Application year: 1990
Main classification: G01R1
IPC codes: H01R13, G01R1