76 



BELL SYSTEM TECHNICAL JOURNAL 



In Fig. 16, the amplification factor, plate resistance, and trans- 

 conductance are shown as functions of control-grid voltage, with the 

 same parameters as were used in obtaining the curves of Fig. 15. Of 

 particular interest in these curves, are the unusually high values of 



1000 

 800 

 600 

 400 

 200 

 



o 



z 



^^ 

 uj O 



°^ i 

 iij a. 



200 000 

 160000 

 120 000 

 80 000 

 40 000 

 



o 



^§ 



O 5 



o 2 



< If) 

 cr 



12 000 

 10 000 

 8000 

 6000 

 4000 

 2000 



\ y2 



4 V 



-11 -10 



-7 -6 -5 -4 -3 -2 

 CONTROL GRID VOLTS, Eq 



Fig. 16 — Amplification factor, plate resistance, and transcondiictance of a space- 

 charge-grid pentode as functions of the control-grid voltage. 



transconductance for a tube of this size. For example, at the selected 

 operating point P it is 9200 micromhos. Also of interest is the peaked 

 character of the transconductance curves. Since transconductance is 

 defined by the slope of the plate current-grid voltage curves, which for 

 this tube have i)oints of infiection in them, maximum points must occur 



