1138 THE BELL SYSTEM TECHNICAL JOURNAL, SEPTEMBER 1956 



test exceeds a predetermined value. This causes another relay to lock up 

 and remember the faihu'e until the network reaches the reject location. 

 In a typical transmission test position (Position 10, 35 or 36) a fixed- 

 voltage, swept-frequency signal, 300 to 3,500 c.p.s., is impressed across 

 two terminals of the network. The three tests are for transmission and 

 short and long hne sidetone with suitable terminations connected as in 

 actual use. In each case the signal from two output terminals should be 

 less than or greater than a specified value. This signal is amplified and fed 



Fig. 4 — Test fixture, unloaded. 



