Coaxial Cable and Apparatus

Greatly increasing requirements for long distance telephone circuits have made imperative the development of a new transmission system with greatly increased capacity. The transmission medium for the newly developed L-4 system consists of coaxial cable, manholes, repeater housings, and other required appurtenances. Critical to the system is the coaxial design. The uniformity of transmission characteristics over a very broad band of frequencies made the 0.375 inch disk-insulated serratecl-seam coaxial the fundamental building block of the L-4 system. The 0.375 inch coaxial cable shown in Fig. 1 has been standard in the Bell System for over 20 years; cables containing up to 12 coaxials were available until 1964. However, the increasing demand for telephone channels dictated the urgent development of Coax 20. The transmission requirements established for the L-4 system necessitated placing repeater stations approximately every two miles along the cable route. At these locations, provisions must be made for the connection of electronic and associated support equipment to the cable. Facilities at these locations include manholes, terminals, and sealed apparatus enclosures. The design and development of these facilities were directed at providing environmental, mechanical, and electrical protection for the electronic equipment at these sites. The natural 1065