Patent GB-470760-A (GB)
Title: Improvements relating to the manufacture of high frequency electric cables
IPC: H01B11/18
Filed: 1936-02-17
Abstract: 470,760. Cables; couplings. TELEGRAPH CONSTRUCTION & MAINTENANCE CO., Ltd., SMITH, E. W., DEAN, J. N., and MATTINGLEY, F. Feb. 17, 1936, Nos. 4851 and 21156. Addition to 467,268. [Classes 36 and 38 (i)] A high-frequency signalling cable of the airspace type comprises inner and outer coaxial conductors or twin conductors enclosed within a common sheath, the inner conductor or conductors being separated from the outer conductor or sheath by radially slotted insulating washers spaced in pairs or larger groups along the inner conductor or conductors. The washers of each pair or group are in adherence or positively interconnected with one another to form a spacing member formed wholly of insulating material. The washers may be of thermoplastic material or mica and may be employed with bushes or rim attachments so that they may be used for cables having inner conductors and outer conductors or sheaths of differing diameters. In the construction shown in Figs. 3 and 4, each washer 1 is formed with a conductor-receiving slot 2 and a diametrically opposite lug 7. The washers are used in pairs with the lug of one washer engaging the slot in the other, preferably by a dovetailed connection. The two washers are spaced apart by enlargements 8 on each side of the lug 7. Perforations 11 may be provided in the washers to reduce the amount of solid insulation in the cable. In another construction, Figs. 8 and 9, the washers comprise a hub portion 12 and a rim portion 14 connected by a thin conical portion 13 which may have slots 16. These washers are formed of thermoplastic material and are employed in pairs, the two washers being secured together at their hubs or rims by rendering these portions adhesive by heat and then pressing them together. The washers may be applied to the inner conductor or conductors by a machine having two magazines from which the washers are struck two at a time from opposite directions on to the conductor or conductors, the adjacent faces of the washers being in contact and having been previously covered with adhesive from a pad or pads placed adjacent the open ends of one or both magazines. In another method, holders are arranged in pairs along the length of the conductor and washers are fed to the holders one by one. The washers are then smeared with cement, or warmed to render them adhesive, and the holders are brought together on to the conductor so as to unite the two washers of each pair. The holders are then released and the conductor moved forward to bring a fresh length thereof into position to receive the next application of washers. The end of the cable may be provided with a terminal coupling comprising a conical socket 16, Fig. 11, having an attaching flange 17, the end of the outer conductor or sheath B being clamped in the socket by a conical insulating plug 18 having a bore or bores through which the inner conductor or conductors A pass. The plug is secured by a check screw 20. The cable armouring B<1> may be clamped within the socket, as shown, or may be secured to the outer surface of the socket. Connection to the conductors may be made by a concentric jack ; or the inner conductor or conductors may be connected direct to the terminal apparatus whilst connection to the outer conductor is effected by a metal tube having a tapered end 19 which fits in the socket. Specification 322,208, [Class 70], is referred to.