Plastic-insulated land communication cables

After a brief comparison of multiquad and coaxial cables for carrier telephony, a description is given of multiquad cables insulated and sheathed with Telcothene, to provide up to 48 or 60 telephone channels per pair. A new type of air-spaced coaxial cable is then described, the spacer consisting of a helical membrane of Telcothene, and the outer conductor a seamless aluminium tube. This was primarily developed to avoid the reflections experienced with disc spacers at very high frequencies, but it is equally suitable for long-distance carrier telephony and television. An account is given of jointing methods, and finally some features of the cables under practical conditions are considered.