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History of the Atlantic Cable & Undersea Communications
from the first submarine cable of 1850 to the worldwide fiber optic network

1950 Key West - Havana Cable
(Florida - Cuba)

This was one of the first of a new generation of American cables, made by the Simplex Wire & Cable Company.

Bell Telephone Laboratories had resumed research on submarine telephone cables after the end of World War II, and Simplex was invited to participate in cable and repeater housing development. In 1948 Simplex manufactured 20 nm of coaxial cable with six repeaters, which was laid by CS Lord Kelvin in the Bahamas.

The 1950 cable shown below, laid between Key West and Havana by CS Lord Kelvin for the Cuban American Telephone & Telegraph Company, was the first commercial system to use the new design, and had twin southbound and northbound cables, 114.55 nm and 124.97 nm in length respectively. This was the first full trial of twin deep-water telephone cables with one-way repeaters; the cable remained in service until 1989, after which it was used for scientific research.

This film from the AT&T Archives shows the design, construction and laying of the cable.

The center conductor is a solid copper wire surrounded by three copper ribbons spiraled along its length. A polyethylene dielectric separates this from the outer conductor, which is also segmented, formed of six copper ribbons.

Three flexible repeaters were used in each cable, each with three 175HQ tubes specially designed by Bell Labs for the high reliability needed for undersea work, and built by Western Electric. The repeaters were powered by DC supplied from the shore stations; the capacity of the cable was 24 voice-frequency channels, each of 4kHz bandwidth.

Twin cables were also used on the Atlantic Missile Range System installed in 1953 by HMTS Monarch (4), and on the cable which opened a new era of long submarine telephone cables, TAT-1 across the Atlantic in 1956. The same high-reliability tubes were used in TAT-1, HAW-1, and other cables of this design, and no failures were ever recorded.


For further information on the history of the Key West - Havana telephone cables see this article by J. Gregory Griffin.

Last revised: 10 December, 2016

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