. The Bell System technical journal . ander with means for adjusting the current through therelays used in the multiplex printing telegraph system and includesseveral switches used in the control of the latter apparatus. In designing the amplifier the necessity of maintaining continuousoperation and easily and quickly remedying any minor troubles was con-sidered of the utmost importance, and this led to its being made largeenough so that work may be done inside of it without having to remove 1* W. A. Knoop, Patent U. S. No. 1,523,430, January 20, 1925. 438 BELL SYSTEM TECHNICAL JOURNAL it from
. The Bell System technical journal . ander with means for adjusting the current through therelays used in the multiplex printing telegraph system and includesseveral switches used in the control of the latter apparatus. In designing the amplifier the necessity of maintaining continuousoperation and easily and quickly remedying any minor troubles was con-sidered of the utmost importance, and this led to its being made largeenough so that work may be done inside of it without having to remove 1* W. A. Knoop, Patent U. S. No. 1,523,430, January 20, 1925. 438 BELL SYSTEM TECHNICAL JOURNAL it from the circuit and take it apart. All of the circuit elements may be reached from the back of the cabinet without disturbing anything else, and on several occasions this arrangement has proved of great value. Power Supply for Amplifier Three sets of storage batteries are required for an amplifier. Thefilaments are heated by a 6 V. 500 AH storage battery. The platevoltage for the first three stages is supplied by a 250 volt 1 AH storage. Fig. 5. battery while the plate voltage for the last stage is supplied by a275 V. 4 AH storage battery. These batteries are in the generalbattery room of each cable station and are handled by ordinarymethods, the only special precautions necessary being the shielding SUBMARINE TELEGRAPH CABLES 439 of the leads from battery to amplifier and the avoiding of loose switchcontacts. Results Obtained in Service The first two amplifiers built were put in operation on the NewYork-Azores cable in September 1924, and after a few weeks testing aspeed of 65 cycles per second or about 2,080 letters per minute incable code was demonstrated. In the fall of 1926 three additionalpermalloy loaded cables were completed and equipped with vacuumtube amplifiers. They are laid between New York and Bay Roberts,Newfoundland, between Bay Roberts and Penzance, England, andbetween Fayal, Azores, and F^mden, Germany. A speed of ninetycycles has been demonstrated on the New Yor
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Keywords: ., bookcentury1900, bookdecade1920, booksubjecttechnology, bookyear1
