TWELVE-CHANNEL OPEN-WIRE CARRIER SYSTEM 



369 



To obtain satisfactory crosstalk conditions at the higher frequencies 

 some changes in line construction are necessary. To use type J 

 carrier systems on existing open-wire routes, methods were devised for 

 modifying the line construction in as economical a manner as possible. 



PAIRS 3/4.-9/10 

 J-3 TRANSPOSITION SYSTEM 



60 70 80 90 100 110 120 



FREQUENCY-KILOCYCLES PER SECOND 



Fig. 4 — Near-end and far-end crosstalk — J-3 transposition system. 



For new lines, such as the new part of the Fourth Transcontinental 

 line,® advantage was taken of the greater degree of freedom in struc- 

 tural design which was possible. 



Figure 5 shows three types of open-wire pole head configuration 



