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BELL SYSTEM TECHNICAL JOURNAL 



which is shown in Fig. 7. In this unit is provided means for control 

 and adjustment of the relays and also means to compensate the type 

 of signal distortion commonly described as the "wandering zero" 

 which results from the inability of the system as shown in Fig. 5 to 

 transmit direct current. 





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1 



Fig. 7 — Relay control desk 



Amplifiers of the type described are in commercial operation at all 

 terminals of the Western Union and Deutsch Atlantische loaded cables. 

 In this extensive commercial use they have been shown to require 

 considerably less maintenance than the moving-coil instruments 

 which are commonly used on non-loaded cables, and in fact the loss 

 of time in operation due to troubles in the amplifiers has been almost 

 entirely negligible. It is of interest to note that it has been possible 



