456 



BELL SYSTEM TECHNICAL JOURNAL 



As the plate resistance is increased all coefficients decrease, but Co 

 decreases more rapidly than does Ci. The question then arises as 

 to the conditions which would lead to the smallest amount of distortion 

 while maintaining a definite fundamental power output at a definite 



-3Z -30 -Z& -26 -24 -22 -20 -18 -Ifc -14 -12 

 V0LT5GRID POTENTIAL 



Fig. 7 — EL tube No. 109,150. External resistance = 15,000 ohms. 

 // = 1.1 amperes 



plate potential. This depends evidently upon the desired power. 

 The results in an illustrative case are depicted by Fig. 9, which 

 represents the level of second harmonic current referred to the funda- 

 mental current (A) plotted as a function of the external plate resistance. 

 At the point of minimum distortion — in which the second harmonic 



Ep = IJO VOLTS 



Ep=l40 

 C-£p = lfcO 

 d-Ep = 200 

 e-Ep-240 



-32 -30 -28 -2fe -24 -22 -20 -18 -16 -14 -12 -10 -8 -fe -4 

 V0LT5 GRID POTENTIAL 



Fig. 8— EL tube No. 109,150. External resistance = 30,000 ohms. 

 // = 1.1 amperes 



