INDUCTIVE LOADING FOR TELEPHONE PAClLITIEg 761 



Type J loading is radically different from that used with the Types C and B 

 loading, primarily because it is usually desirable to include series inductance 

 along with shunt capacitance, in proper proportions, because of the relatively 

 high ratio of distributed inductance to distributed capacitance in the disc- 



Fig. 34 — Building-out units used in electrical adjustments of type J carrier loading 

 sections. Upper View: Continuously-adjustable wire wound unit. Prior to adjustment it 

 has a distributed shunt capacitance of about 275 mmf, and a series inductance of about 

 16.5 microhenrys; Lower View: Single section non-adjustable artificial line, providing a 

 shunt capacitance of about 250 mmf (single condenser) and a total series inductance of 

 about 15 microhenry (2-coils). This particular unit simulates a length of about 53 ft. of 

 disc-insulated cable pair. Other (multi-section) artificial line units simulate longer lengths 

 of cable pair. 



insulated cable with which the loading is used (about 1.4 m.h. inductance 

 and 0.025-mf capacitance, per mile). 



Two types of building-out units are required, (1) a continuously adjust- 

 able, wire-wound unit which is used for making precision adjustments, and 



