Electron tubes for the transatlantic cable system

Electron tubes for use in repeatered underwater telephone cable systems must be capable of operating for many years with a reasonable probability of proper functioning. In the new transatlantic telephone cable system the section of the cable between Nova Scotia and Newfoundland contains repeaters developed by the British Post Office Research Station at Dollis Hill. These repeaters are built around the type-6P12 tube developed at that research station. The repeaters contained in the section of the cable system between Newfoundland and Scotland are of Bell System design and depend on the 175HQ tube developed at Bell Telephone Laboratories. In this paper the philosophy of repeater and tube design is discussed, and the fundamental reasons for arriving at quite different tube designs are pointed out. Some of the tube development problems and the features introduced to eliminate potential difficulties are described. Electrical characteristics for the two types and life test data are presented. Fabrication and selection problems are outlined and reliability prospects are discussed.