1324 THE BELL SYSTEM TECHNICAL JOURNAL, NOVEMBER 1956 



Reproducibility 



The curves presented in this section are all for the same tube, one 

 which is representative of a group of 50 which were built at the conclusion 

 of the Ml 789 development program. The tubes in this group had char- 

 acteristics falling within the following ranges. The numbers represent 

 the range containing 90 per cent of the tubes tested. 



Accelerator Voltage for 40 ma 2,500-2,700 



Helix Voltage for maximum low-level gain 2,350-2,450 



Low-level gain 33-37 db 



Gain at 5 watts output 31-35 db 



Maximum power output J 40.5-42 dbm 



\(1 1.2-15.8 watts) 



2000 2100 2200 2300 2400 2500 2600 2700 



HELIX VOLTAGE IN VOLTS 



2800 2900 



3000 



Fig. 29 — Low-level gain as a function of helix voltage for various beam cur- 

 rents. The dotted line represents the locus of the maxima of the curves. 



