22 



BELL SYSTEM TECHNICAL JOURNAL 



40 



UJ u 

 ^^ 



'£1 z 



UJ H 

 IX I 



I o 



•-1- 



z z 



— UJ 



UJ o 



36 



32 



28 



24 



20 



60 70 80 90 100 



TOTAL SPACE CURRENT IN MILLIAMPERES 



Fig. 10 — The input-output reaction at 150 megacycles. 



Conclusion 



The development of this ultra-high-frequency pentode demonstrates 

 that amplifier tubes of the negative grid type are usable at higher 

 power levels and frequencies than have been reported previously. 

 The extension of the principles underlying the design of this tube to 

 the design of a tube with approximately ten times the output is now 

 being considered. This type of development removes a practical 

 barrier which has, up to the present, prevented the successful utiliza- 

 tion of this frequency range. 



PART II— THE CIRCUIT 



By N. E. SOWERS 



Introduction 

 In the first section of this paper A. L. Samuel has described the 

 development of a push-pull pentode designed to function as a stable 



i 



