TELEPHONE EQUIPMENT FOR LONG CABLE CIRCUITS 113 



needed. Thus, the requirements of the cable plant have been such 

 as to emphasize the economic importance of the equipment design. 



To meet these requirements it has been necessary to undertake a 

 comprehensive plan of development affecting many types of equip- 

 ment. This has involved careful consideration of both the electrical 

 arrangements and the mechanical design, which are being closely 

 coordinated with the purpose that both should contribute to the 

 highest degree of efficiency in the functioning of the system. 



It is not possible in this paper to give many details concerning 

 these developments, but it is desired to present some of the principal 

 features as applied to typical cases. Among the more important of 

 these are the telephone repeater equipment, the testboard equipment 

 and the signaling equipment. These are closely associated with 

 each other in their operation, as well as in their physical location, 

 and it has been necessary, in the design of all units to have due regard 

 to the system as a whole. 



Telephone Repeater Equipment 



The function of the telephone repeater as an amplifier in long 

 distance lines is well known. The telephone repeater in its present 

 form has been the chief factor in making long distance cable telephony 

 practicable, and it is probable that the developments in connection 

 with telephone repeaters have been among the most rapid and com- 

 prehensive of any in the toll equipment. It will, therefore, be very 

 interesting to note, in the illustrations which follow, the principal 



Fig. 1 — Box Type Repeater Installation 



