238 THE BELL SYSTEM TECHNICAL JOURNAL, JANUARY 1957 



JF 



/ 



SYDNEY MINES 



BAND 



PASS 



FILTER 



2f 



BAND 



PASS 



FILTER 



REPEATER 

 LF 



HIGH 



PASS 



FILTER 



2f 



BAND 



PASS 



FILTER 



BAND 



PASS 



FILTER 



FREQUENCY 

 DOUBLER 



CABLE 



J L 



J L 



J L 



UJ 



U 

 2 

 HI 



a. 



UJ 



u. 



UJ 



16 15 



14 13 12 11 10 



REPEATER NUMBER 



(b) 



LU 



o 



z 



UJ 



a. 

 lu 

 u. 



UJ 



a. 



Fig. 12 — Fault location — loop-gain method, (a) Block schematic. Fre- 

 quency/is in the band 260-264 kc. (6) Diagram of display. 



r-| \ SYDNEY 

 -■ "- ' MINES 



REPEATER 



Fig. 13 — Fault location: pulse method. A. Pulse generator. B. Display of 

 received pulses. C. Point of intermodulation (output of amplifier). 



