i.o.inixc roh' //■/./■riioMi c/iui'/rs 



253 



TABLE XI 



Types of Toll Cable Facilities 



type of loadin;^ for much shorter distances. For further discussion 

 of the use of repeatered loaded hues reference is made to recent 

 papers presented before the Institute by Mr. J. J. Pilliod '- and Mr. 

 H. S. Osborne.-^ 



//-68-P versus II-IOQ-P Loading. The standardization of the 

 H-63-P loading to replace the H-10()-P loading for association with 

 H-174-S loading, is of particular interest in illustrating the reactions 

 of repeater rec|uirements on loading design. Phantom circuits neces- 

 sarily have a lower attenuation constant than the associated side 

 circuits, when the loading is designed to meet the same standard of 

 cut-off frequency and the coils are spaced at the same loading points. 

 When repeaters are used on such loaded phantom circuits, the net 

 equivalent is practically no lower than the net equivalent of the asso- 

 ciated side circuits, due principally to the fact that the loaded sides 

 and phantoms have practically the same velocity and cut-off fre- 

 quency characteristics. 



Under present operating conditions for short small gage loaded 

 circuits of such lengths that satisfactory transmission results can be 

 obtained without using telephone repeaters, there is ordinarily no 

 important advantage in having the phantom circuit more efficient 

 than the side circuits. It is a distinct operating con\'enience, of 

 course, to be able to use the phantom circuit and its associated side 

 circuits indiscriminately for the same class of service. 



Having the above situations in mind, it was decided to redesign 

 the phantom loading so that it would have approximately the same 



--"Philadelphia-Pittsburgh Section of New York-Chicago Cable," J. J. Pilliod, 

 Trans. A. I. E. E., Vol. 41, 1922, p. 446; Bell System Technical Journal, Jan., 1922. 



-■' "Telephone Transmission over Long Distances," H. S. Osborne, Trans. A. I. E. E- 

 Vol. 42, 1923, p. 984. 



