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THE BELL SYSTEM TECHNICAL JOURNAL, MARCH 1956 



Fig. 7(a) — Line unit. 



number of trunks at 10 and equipping or reassigning lines as needed to 

 obtain the trunk loading for the desired grade of service. The six cross- 

 points, the passive line circuit and scanner gates individual to each line 

 are packaged in one plug-in unit to facilitate administration. The cross- 

 points are placed on a printed wiring board together with a comb of plug 

 contacts as shown in Fig. 6. The entire unit is then dipped in rubber and 

 encapsulated in epoxy resin, as shown in Fig. 7(a). 



This portion of the unit is extremely reliable and therefore it may be 

 considered as expendable, should a rare case of trouble occur. The passive 

 line circuit and scanner gate circuit elements are mounted on a smaller 

 second printed wiring plate (known as the "line scanner" plate, see Fig. 

 7(b) which fits into a recess in the top of the encapsulated line unit. Cir- 







Fig. 7(b) — Scanner plate of the line unit shown in Fig. 7 (a). 



