74 



BELL SYSTEM TECHNICAL JOURNAL 



chosen at P in Fig. 15, with a screen potential of 90 volts and a grid 

 potential of — 2 volts, the plate current, screen current, and net 

 current are 24, 0.5, and 23 ma, respectively, making a total space 



•^ 10 



y- uj 



z a. 



lli uj 



a. Q. 



Z -J 



UJ 5 



UJ -^ 



tt Z 



u - 

 m 



211 



All 



5^S ' -^ 



I-' 0^ 



z i^ 



a 5 



a < 



3 -1 



C5 

 z z 



20 40 60 80 100 



120 140 160 

 PLATE VOLTS, Er 



180 200 220 240 260 280 



Fig. 14 — Characteristics of a space-charge-grid pentode. Plate current, /p, 

 screen current, /„ and net (space-charge-grid) current, /„, as functions of the plate 

 voltage with the indicated values of control-grid voltage as parameters. Screen-grid 

 voltage, £, = 90 volts. Net (space-charge-grid) voltage, £„ = 15 volts. 



current of 47.5 ma drawn from the cathode, nearly half of which is 

 collected by the space-charge grid. 



Another point of interest in Fig. 15 is the flattening out of the plate- 

 current characteristics at the higher values of plate current, in a manner 



