THE L3 SYSTEM — DESIGN 



831 



Fig. 23 — An engineer testing pilot transmission in an L3 repeater hut. 



The adjustment of the manual gain equahzers to an accuracy of db0.02 

 db in a rapid and direct way is accomplished by special equipment 

 described in the companion equaHzation paper.^^ A visual gain and delay 

 transmission measuring test set, capable of measuring gain to ±0.05 db 

 and delay to ±0.02 microseconds, has been developed for observing the 

 line performance and adjusting delay equalizers when the system is used 

 for television. 



A maintenance center is provided at about 200-mile intervals along 

 the line to service the equipment removed from repeaters. At these points 

 facilities are provided for the following: (1) electron tube testing; (2) 

 regulator repair and adjustment; (3) transmission measurements on 

 passive components; and (4) ampUfier testing of sufficient scope to permit 

 changing tubes and to determine whether an ampUfier is suitable for 

 further service in the line. 



