Patent GB-613642-A (GB)
Title: Improvements in or relating to arrangements for switching amplifiers used in high frequency electric communication circuits
IPC: H04B1/74
Filed: 1946-06-24
Abstract: 613,642. Two-way transmission. STANDARD TELEPHONES & CABLES, Ltd., and ROCHE, A. H. June 24, 1946, No. 18855, [Class 40 (iv)] In an arrangement similar to that disclosed in Specification 527,564 for replacing a signal amplifier of a repeater by a spare amplifier, the plug and jack connections used in the prior arrangement are replaced by U-links in order to avoid the presence of jack-spring contacts in the main circuit. Fig. 1 shows a two-way repeater of known type at an unattended station in a co-axial cable transmission system. The incoming lines are connected to input power separating filters IE, IW, the signal outputs of which are led through building- out networks 2E, 2W and equalizers 3E, 3W and thence to line amplifiers 4E, 4W through co-axial U-link connector systems 5E, 5W. The output circuits of the amplifiers are connected over similar U-link systems 6E, 6W to the output power separating filters 7E, 7W and thence to the outgoing lines. Pilot regulators 8E, 8W of known type are connected to the input of the corresponding output power separating filters, each regulator being provided with a co-axial terminal socket 9E, 9W from which the rectified voltage for the control of the amplifiers may be obtained. The common power supply unit 10 is provided with a power jack 11. The U-link connector systems 5, 6 are similar, and each comprises two pairs of co-axial terminal sockets 12, 13; 14, 15; pairs 12 and 14 being each connected in parallel to the amplifier pair 13 to the line equalizer, and pair 15 to the output separating field. The sockets of each of the pairs 12, 14 are normally connected to those of the corresponding pairs 13, 15 by individual co-axial U-links (not shown). The spare amplifier circuit, Fig. 2, comprises a spare amplifier 45, two sets of double change-over contacts 16, 17 operable simultaneously by a key or relay (not shown), and two grounded terminating sets 18, 19 having impedances equal to those which normally terminate the amplifiers of Fig. 1. Four co-axial sockets 12s-15s are provided; 12s and 13s being normally connected together over contacts 16, and 14s and 15s over contacts 17; while the input and output circuits of the amplifier are connected to the terminating sets. To replace amplifier 4E (or 4W) by the spare amplifier, jacks 11 and 11s, and 9E (or 9W) and 9s are connected by a power cord and a co-axial patching cord respectively, and the amplifier 4s is left for its gain to reach the correct level. One of the U-links connecting socket pairs 12 and 13 and one of those connecting 14 and 15 are then removed and sockets 12s-15s are connected by patching cords to the sockets 12-15 from which the U-links have been removed. The remaining U-links are next removed, the connections of the line amplifier being maintained over contacts 16, 17. On operation of these contacts the spare amplifier is switched into circuit to replace the line amplifier, which itself is connected to the terminating sets. To connect the line amplifier into circuit again the above operations are repeated in reverse order. In a modification (Fig. 3, not shown) the spare amplifier is provided with a separate pilot regulator, socket 9s being omitted. Specification 609,627, [Group XL (c)], also is referred to.