AN IMPROVED TELEPHONE SET 



243 



signed to be easy. Other components are permanently mounted, and are re- 

 placeable only in a shop. Switch assembly and transmission circuit com- 

 ponents are so mounted and are completely enclosed and protected. The dial 

 has no adjustments to be made in the field, and the ringer only one, bias 

 tension which is rarely changed. The set functions completely with the cover 

 removed. No parts or wiring are attached to the cover. This facilitates both 

 production assembly and field servicing. 



i*^s# 



Fig. 2 — Internal view of 500-set. 



The success of such a design depends, of course, on precise knowledge of 

 the service conditions to be met, how to meet them technically, and how to 

 design and manufacture a set so it will keep on meeting them with the 

 minimum of attention or expense thereafter. 



Functional Design in Relation to Objectives 



The main objective of the new set design was to reaUze acceptable per- 

 formance requirements over longer distances from the central office, or with 

 finer gauge cable conductors, and to do this with existing central office facil- 



