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BELL SYSTEM TECHNICAL JOURNAL 



variable auxiliary impedances were inserted at suitably chosen points 

 in the line and network circuits. By the adjustment of these elements, 

 it was found that the balance could be raised to any desired value 

 for any particular channel, but that in so doing, the balance on some 

 of the others would be impaired. By careful adjustment, however, it 

 was possible to secure a balance for all channels within the range 

 previously mentioned. As the transmission equivalent of the cable 



Fig. 11 



increases with the frequency, the over-all channel gains must be 

 increased in the same manner in order that all circuits may have the 

 same over-all equivalent. The networks were therefore arranged so 

 that the higher frequencies would have the better balance, as in that 

 way the margin of balance over gain could be made substantially 

 the same for all channels. Since this margin should not be allowed 

 to fall below a fairly definite minimum if the circuit is to have the 



