The Application of Vacuum Tube Amplifiers to 

 Submarine Telegraph Cables 



By AUSTEN M. CURTIS 



Synopsis: Vacuum tube amplifiers have been developed for use in sub- 

 marine telegraph reception and at present are in successful operation on 

 four high speed permalloy cables. There is no limit to the speed at which 

 vacuum tube amplifiers may be operated and in the present stage of de- 

 velopment, the rate at which messages may be passed over loaded cables 

 of the length used in the Atlantic Ocean is determined by the cable itself 

 and the mechanical transmitting and receiving apparatus. In regard to 

 maintenance, vacuum tube amplifiers have a great advantage in that they du 

 not require any delicate mechanical adjustments. 



THE laying of the new permalloy loaded cable between New York 

 and Fayal (Azores) in September 1924 marked the most radical 

 change in construction and operation of submarine cables that has 

 taken place in many years. During 1926 three additional cables of 

 this type were laid, the four sections being arranged to provide a line 

 of communication between New York and England and another 

 between New York and Germany, The traffic handling capacity of 

 these cables when ultimately developed to its maximum by suitable 

 terminal apparatus, will be nearly equal to that of all the other cables 

 between North America and Europe combined. 



The construction of these cables and the principles underlying their 

 operation have already been described by O. E. Buckley ^ before the 

 American Institute of Electrical Engineers in June 1925. The speed 

 of operation of loaded cables of this type is many times that of the 

 older non-loaded cables, and new apparatus has had to be developed 

 to realize the full advantage offered by permalloy loading. One of 

 the most important of these new developments has been the signal 

 shaping vacuum tube amplifier, which is now in use on the four North 

 Atlantic loaded cables. 



The purpose of this paper is to point out the requirements which 

 must be met by cable amplifiers, particularly those used on high 

 speed loaded cables, and to describe how these requirements have been 

 fulfilled in the present signal-shaping amplifier of the Western Electric 

 Co. It will not be necessary to consider in any detail the general 

 principles of operation of telegraph cables as these have been discussed 

 with reference to non-loaded cables by Mr. J. W. Milnor- and are 



' Bell System Technical Journal, Vol. 4, July 1925; Journal of the Americaji Institute 

 uf Electrical Engineers, Vol. XLIV, No. 8, August 1925. 



^"Submarine Cable Telegraphy," Journal of the American Institute of Electrical 

 Engineers, Vol. 41, February 1922. 



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