SOME APPLICATIONS OF TYPE "J" CARRIER SYSTEM 339 



for type C carrier operation are not necessarily satisfactory for the 

 operation of the new system. 



The three Hnes under consideration were practically of the same 

 construction, being twelve-inch phantomed lines originally built for 

 voice frequency circuits only and later modified for the application of 

 type C carrier systems. Over lines of this type, it is practicable to 

 operate a single type J system without any material change in the line 

 wire because no crosstalk considerations are involved, although it is 

 necessary to select by transmission measurement pairs which are free 

 from absorption effects. Where more than one system is required a 

 transposition arrangement has been designed for use with line con- 

 ductors of a non-phantomed pair spaced six inches apart and thirty 

 inches between conductors of horizontally adjacent pairs. This design 

 can be used either for new wire or for existing wire retransposed, and 

 can be applied without regard to the existing phantomed transposition 

 design, thereby permitting respacing and retransposing any portion of 

 the existing wire, a phantom group at a time if desired. 



Advance Engineering 



With these operating limitations a review of the circuit requirements 

 established a plan to place a J carrier system on one of the phantom 

 groups of the Dallas-Longview line during 1938. This system would 

 not only provide sufficient circuits to meet the additional requirements 

 but would furnish sufficient spare circuits to release one phantom 

 group of twelve-inch wire for respacing and retransposing. This plan 

 was not applicable to the Dallas-Houston and Dallas-San Antonio 

 lines since circuit relief was required for the 1937 business, and the J 

 carrier system would not be available until 1938. These lines each 

 consisted of five crossarms of 104 mil wire over the greater portion of 

 their length. An inspection showed that, although the poles were of 

 sufficient strength to support additional crossarms, it would be 

 difficult to maintain the necessary wire clearance with an additional 

 crossarm below the existing wire and also that new wire so placed 

 would be susceptible to interference from possible breaks in the wire 

 above. 



The solution of this problem was the addition of a crossarm two feet 

 above the others on a simple extension fixture. This fixture shown in 

 Fig. 1 consists of a four-inch steel "H" beam fastened to the pole by 

 the through bolts which also support the two upper crossarms. By 

 placing four pairs of six-inch spaced conductors on the new crossarm 

 and by using four type C carrier systems, sixteen additional circuits 

 were obtained to furnish the circuit relief for 1937 and, in addition to 



