

N-1 CARRIER TELEPHONE SYSTEM 



427 



sembly into several units which could be connected together in the equip- 

 ment assemblies. The more complicated filters and equahzers thus are com- 

 prised of two or more such units. Except for the signaUng frequency filter 

 the unit assemblies for all filters and equalizers in the system have the same 

 housing and the same mounting facilities. This division of filters and equal- 

 izers into combinations of externally identical units permits more efficient 



Fig. 7 — Filter units. Upper left: Voice frequency unit; Upper right: Carrier frequency 

 Unit; Center: Common parts, voice and carrier frequency units; Lower: 3700-cycle signal 

 frequency filter. 



use of space in equipment assemblies and is instrumental in lower manufac- 

 turing costs by utilization of common assembly details. 



The unit assembly details consist of a drawn aluminum shield can equipped 

 with mounting lugs and a cage type framework comprising two molded 

 phenol end plates held together by four corner rods which also serve as 

 four of the eight available terminals in the terminal side end plate. In the 

 carrier frequency units, two duo-lateral type inductors wound on a common 

 phenoHc core tube are held in place by means of keyed recesses in the end 

 plates. A threaded insert in each of the end plates supports the magnetic 



