US 2714194 A
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Description (OCR text may contain errors)
July 26, 1955 w. BEYNINK, 2,714,194
INTERCONNECTING DEVICE FOR HIGH-FREQUENCY CURRENTS Filed Nov. 10, 1951 2 Sheets-Sheet 2 INVENTOR Willem Beynink nited States Patent ()iifice a '21 a i :1 iizgu T 3' Patented duty no, 1 55115 ,TPEVECE FJR HEGH- CURRENTS Ap; iicatiorl November 14 1951, Serial No. 255,760
Gaines priority, application Netherlands December 16, 1959 This invention relates to interconnecting devices for high-frequency currents, which comprises at least two contact plug panels, of which one is rigidly secured to a frame and the other together with associated apparatus (for example a line telephony amplifier) is fitted as a detachable assembly in the frame, said panels comprising two rows of parallel contact sockets or contact pins which are adapted to be interconnected in pairs by means of four-pin plugs with substantially aligned contact members. The contacts fitted to the frame constitute the connecting points of the supply voltages and of the incoming and outgoing lines, the corresponding connecting points of the detachable apparatus being directly connected to said first-named points by means of plugs.
When such interconnecting devices are employed for comparatively high frequencies, for example several hundreds of kc./s., parasitic couplings often occur, even when shielding as carefully as possible, which involve difficulties. In line telephony, the said coupling is evidenced by an excessively high cross-talk level.
We have found that this undesirable coupling is due to magnetic stray fields which are produced by the currents flowing through the plugs and plug sockets.
According to the invention the said difi-lculties are avoided by providing, for interconnecting a two-conductor high frequency line, each panel with at least two pairs of contact members which are juxtaposed according to the corner points of a rectangle and are cross-wise connected at least on one of the panels.
in order that the invention may be readily carried into effect, two examples will now be described in detail with reference to the accompanying drawings, in which:
Fig. 1 shows a repeater bay in which an interconnecting device according to the invention may be used;
Fig. 2 is a cross-section on the line IIII of Fig. l on a larger scale;
Fig. 3 shows how the current circulates in the device shown in Fig. 2;
Fig. 4 shows diagrammatically and perspectively a device according to the invention and Fig. 5 illustrating a second example of the invention.
Fig. 1 .shows a repeater bay for use in line telephony (carrier-wave telephony) in which a high frequency line connection with a frequency range of, for example, 12 to 200 kc./ s. comprises a number of, say, 48 call channels modulated on separate carrierwaves, this frequency range being transmitted through an appropriate line connection (cable with associated amplifier apparatus).
The bay consists of a frame 1 comprising a number of detachable channel units 3, 3 and so on, 5', 5 and so on. The channel unit 5 comprises an amplifier, and the channel unit 3 comprises several filter networks for correcting the frequency characteristic curve (so-called equalisation apparatus) and other auxiliary apparatus. The incoming cable 7 is connected to two plug sockets 11 and 13 fitted on an insulating contact panel 15 which is secured to an intermediate panel 17 of the frame. Right above panel 15 is located a similar contact panel 19 which is fitted to the channel unit 3 and whose sockets 21 and 23, located right above sockets i1 and 13, are connected through a short cable 8 to the input terminals of the equalisation network.
The output terminals of this network are connected to two other contact sockets 25 and 27 of panel 19, a cable 33 being connected to two subjacent sockets 29 and 3?. of panel 15. The contact sockets 11, i3, 21, 23 and 25, 27', iii, 31 respectively are interconnected in pairs by means of four-pin plugs of the type (35) .shown in Fig. 2 with four contact pins arranged in line, the connections being clearly shown in this figure. The remaining, not enumerated contact sockets on panels 15 and 19 serve to supply feed voltages and auxiliary voltages to the amplifier. For the sake of clearness the connecting plugs required therefore are not shown in the drawing.
The cable 33 is the incoming cable for the amplifier channel unit 5 and is connected to plug sockets -I. an 43 fitted to a contact socket panel 5-5, which sockets connect, as described, through a four-pin plug with contact sockets .7 and 4% carried by a contact panel 53 which is fitted to the channel unit 5. The sockets 47 and 4& are connected to the input circuit of channel unit 5, the out put circuit connectin with the out oin cable 53 similarly as described in conjunction with channel unit 3 and cable 33. The said cables are all of the shielded type.
Below the apparatus referred to, the bay comprises exactly similar apparatus 3 5 and so on, which serves for transmitting a second series of 48 calls within the range of 12 to 200 kc./s. through a second cable.
Fig. 3 shows how the current circulates in the sockets 11, 13, 21, 23 and in the plug 35 at a given instant. it is seen that two loops have formed which are traversed by current and produce magnetic fields. These fields are oppositely directed (arrows 55 and $7), it is true, but are specially separated so that they do not neutralise each other in the surrounding space. In this manner an undesirable coupling is produced with the loops similarly formed on the contact panels 15, t9 and so on of the second line connection, this coupling being evidenced by an unduly high cross-talk level between corresponding call channels of the two line connections.
This disturbance could be eliminated by means of a well constructed detachable shielding cap, but this is a comparatively expensive and intricate solution. A simpler solution is illustrated in Pig. 4. As appears from this figure, not only the sockets ll, 13, 21 and 23 but also the adjacent sockets til, 63, 655 and 67 are in use for interconnection of the high-frequency line connection. The sockets 21, 23, and 67 located on panel 19 according to the corner points of a rectangle are connected crosswise and so are the sockets i1, 13, 61 and 63 on panel The contact sockets 61, 63, 65 and s7, similarly to the sockets 11, 13, 21, 23 are interconnected through a fourpin plug similar to plug 35.
Fig. 4 shows in perspective how the current circulates in this device. From this figure it is seen that oppositely directed magnetic fields are produced in immediately adjacent loops, so that these fields neutralise each other for the greater part. To this end it is essential that the two parallel-connected current paths constituted by the two four-pin plugs and associated sockets should be equal in regard to form and resistance and be located immediately adjacent each other. Although these conditions can never be fulfilled completely, it is found in practice that the expedients referred to yield a considerable disturbance elimination in and through neighbouring channels and that it is feasible, without additional shielding or suchlike means, perfectly to satisfy normal requirements with respect to crosstall Satisfactory results are obtained by not connecting the junction wires of the supply cables 7 and 8 to the midpoints of the cross-connections, as in Fig. 4, but directly to the contact sockets, for example cable '7 to sockets 61, 63 and cable 8 to bushes 21 and 23.
Fig. 5 shows another example of the device according to the invention, which may be used if the output circuit of an apparatus is connected through a short lead to the input circuit of a following apparatus, as is the case, for example, with the apparatus (channel units) 3 and 5 in Fig. 1, which apparatus are interconnected through a short cable 33.
Fig. 5 shows diagrammatically the connections between each series of four contact sockets located at the corner points of a rectangle at the right-hand end of panels 15, 19 and those at the left-hand end of panels 45 and 51 in Fig. 1. As shown in Fig. 5, only the uppermost of two series of four contact sockets are cross-wise interconnected. The absence of the remaining cross-connections makes no difference in the flow of current. The advantage is, however, that the two parallel-connected interconnection circuits are longer than in Fig. 4, with the result that the chance of the resistances of the two circuits being slightly unequal is reduced and the disturbance field of the junction cable 33-whose conductors are preferably twisted in realitymay be much smaller than that of a twin-core cable.
.Vhat I claim is:
1. Apparatus for connecting a two-wire high-frequency line to an electrical unit comprising a frame, an electrical unit having two input leads and detachably mounted on said frame, said unit being provided with a panel having first and second pairs of contacts thereon disposed at the corners of a rectangle and wire means diagonally crossconnecting said first and second pairs of contacts, said input leads being connected to said cross-connected pairs of contacts, a panel fixedly secured to said frame and provided with third and fourth pairs of contacts disposed at the corners of a rectangle, said third and fourth pairs being colinearly disposed relative to said first and second pairs respectively, wire means diagonally cross-connecting said third and fourth pairs of contacts, said twowire line being connected to said cross-connected third and fourth pairs, and two bridging plugs each having four aligned pins, one of said plugs having its pins inserted in said first and third pairs of contacts to effect a connection therebetween, the other plug having its pins inserted in said second and fourth pairs of contacts to effect a connection therebetween.
2. Apparatus, as set forth in claim 1, wherein said two-wire line is connected to the midpoints of the cross connections.
References titted in the file of this patent UNITED STATES PATENTS 1,625,125 Latour .d Apr. 19, 1927 2,253,136 Richter et al Aug. 19, 1941 2,373,906 Mouradian Apr. 17, 1945 2,594,069 Poehlmann Apr. 22, 1952 2,594,737 Cunningham Apr. 29, 1952 FOREIGN PATENTS 42,702 France Sept. 14, 1933 641,562 Germany Feb. 5, 1937 931,803 France Nov. 3, 1947