NEGATIVE IMPEDANCE TELEPHONE REPEATERS 1061 



SPECIFIC APPLICATIONS 



^lany installations of the new rcpcatci-s have been ciijiiiiccrcd lor 

 completion in 1954. In all eases economic stndies were made and re- 

 sults of these studies broadly confirmed the hidications of the two charts 

 discussed abo\'e. 'J'o bring out more clearly the effectiveness of the E23 

 repeater, it ma^' be worth while to consider a few specific cases invohing 

 installations of the new repeaters being made this year. 



The first case shown on Fig. 3 is in the area of the Pacific Telephone 

 and Telegraph Company. The figure shows th(^ two altcn-natives that 

 were considered for providing additional tandem trunks between San 

 Francisco proper and the East Bay Area, needed this year because of 

 an extension of customer toll dialing arrangements. 



The engineering study for this project was somewhat more com- 

 plicated than would ordinarily be the case because two possible routes 

 of unequal length and with slightly different amounts of submarine 

 cable were involved. The present route which touches Yerba Buena 

 Island is subject to some hazard from dragging ship anchors but the 

 circuit relief would have been cheaper here than on the other route 

 shown, were it not for the new repeaters. The second route is consider- 

 ably less hazardous and, in addition, is sufficiently removed from the 

 present one to provide increased reliabilit}^ under disaster conditions. 

 Without the repeaters, however, the second route would have l)een 

 somewhat impracticable, since it does not allow easy installation and 

 access to required loading points between the two shore lines. However, 

 with two of the new repeaters on each pair of conductors, nonloaded 

 22-gauge cable gives substantially the same effective transmission loss 

 as loaded 19-gauge conductors on the shorter route and over a future 

 period will involve less annual cost per circuit. Furthermore, the use of 

 22-gauge cable permits more than twice as many pairs to be included in 

 the same size sheath in the expensive submarine section. 



The initial installation of the new type repeaters on this cable will 

 total about 1,300, divided between the Main Office in San Francisco 

 and the jNIain Office on the East Ba}^ side. Individual repeater gains 

 are 5 to 7 db at 1,000 cycles but the repeater gain characteristic is shaped 

 to offset the increasing cable losses at the higher frequencies so that the 

 over-all circuit has relatively uniform transmission in the voice range. 



The second case is one where the need for the repeaters results from 

 the complex toll switching system at Chicago, Ilhnois. Here it has been 

 found desirable, because of the great \'olume of toll traffic, to have several 

 toll offices scattered throughout the city and suburbs. In general, toll 

 calls coming into these offices from other cities are completed over toll 



