GB1501860A - Air seal for coaxial cable pairs - Google Patents

Abstract

1501860 Coaxial cable air seals POST OFFICE 19 Sept 1975 [19 Sept 1974] 40878/74 Heading H2E An air seal is formed on a coaxial cable pair by removing the outer sheathing 4 for a predetermined length to expose the outer conductor 2, exposing circumferentially the dielectric 3 along a length of the exposed conductor 2 and removing circumferentially a strip of the exposed dielectric to expose the inner conductor 1. A perforated metal ferrule 8 is then located over the exposed ends of the outer conductor 2 so as to establish an electrical connection therebetween and a resinous substance is then impregnated over the predetermined length of the cable pair to form the air seal. As described, the ferrule 8 may be longitudinally split or comprise a tubular sleeve and may be crimped into its position over the ends of conductor 2. A second longitudinally split brass ferrule 6, 7 may be situated as shown to bridge the dielectric 3. The outer conductor 2 may be braided, the removal thereof to expose the dielectric being effected by drawing the braiding back after an initially circumferential cut, which may be later pulled back over the ferrule 6, 7. A length of heat shrink plastics tube 9 may cover the heat seal, the resinous substance, e.g. epoxy or polyurethane resin, being forced through an aperture 10 therein to completely fill the spaces via the apertures in the braided ferrule(s). A further tube may enclose tube 9. The method may be employed for coaxial pairs in a multipair assembly (Fig. 2, not shown). A cable pair formed with the air seal as described enables the cable to be passed through a barrier across which a pressure difference exists, e.g. a termination plate of a repeater in a coaxial cable transmission system.