1124 THE BELL SYSTEM TECHNICAL JOURNAL, OCTOBER 1951 



the grids and assembled the experimental tube models made important 

 contributions in terms of skill and painstaking effort. It is not practical to 

 name all of the persons involved. 



The development of broad band tubes over the last fifteen years was 

 under the direction of the late Dr. H. A. Pidgeon until 1943, and Mr. J. O. 

 McNally from 1943 to date. The writers wish to acknowledge the impor- 

 tance of their helpful guidance and encouragement. 



APPENDIX 



Meanings of Symbols 



F = Figure of merit 



G = Voltage amplification 



B = Bandwidth between 3 db points 



K = Interstage circuit constant 



Gm = Grid-plate transconductance 



C\ = Input capacitance 



C2 = Output capacitance 



n = Turns per unit distance on grid 



a = Grid-cathode spacing 



b = Grid-screen spacing 



c = Screen-plate spacing 



A = Area of active structure 



h = Plate current, d-c 



M = Ratio of plate current to cathode current 



Eel = Grid-cathode voltage 



Er2 = Screen-cathode voltage 



M = Grid-screen amplification factor 



/o = Cathode current density, d-c 



r = Grid wire radius 



Ip = Amplitude of fundamental component of a-c plate current 



hp = Amplitude of second harmonic component of a-c plate current 



ip = Fundamental a-c plate current component 



iip = Second harmonic plate current component 



Go = Perveance factor 



Eg = Amplitude of grid signal voltage 



p = Frequency X 27r 



/ = Time 



i = a-c plate current 



Units: length in cms; practical electrical units; time in seconds. 



