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BELL SYSTEM TECHNICAL JOURNAL 



With current and voltage directions as in Figs. 16, 17 and 18, the follow- 

 ing Tables I, II and III list the four-pole parameters for the three modes of 

 triode operation in both ^ and Z forms. 



Table I 

 Four-Pole Parameters eor Grounded Cathode Triode 



yil + ^21 + ^22 ^ y22 



D ^^^="^ 



^11 



/321 = 



^21 4- 3^22 



D 



/3ii /3i2 



/321 /322 



3'22 + 



yii 



/322 = — 

 3'li ^22 



Zll 



1 + 



1 + J_ 



yVL M>'22 



yn 



yn + yil + 



M3'22 



-2^12 = — 



yi\ 



Z21 + 



yn yn yn 



[yn yil ynyii^ 



Az 



Zll Z12 

 Z21 Z22 



_1_ 



A/3 



yii ^22 



M« amplication factor. 



The y admittance coefficients appearing in the above tables were fully- 

 explained and discussed in the paper on Vacuum Tube Networks, to which 

 reference has already been made. Suffice it here to say that yw is the 

 admittance of the diode coinciding with cathode and equivalent grid plane 

 and 3/22 the admittance of the diode coinciding with the equivalent grid plane 

 and the anode and finally yix the transadmittance between these fictitious 

 diodes. The admittance yw depends upon the d-c conditions between cath- 

 ode and grid and upon the transit angle for this region alone. The diode 

 admittance >'22 depends in a similar manner upon tlje d-c space charge 

 conditions in the grid-anode region as well as upon the transit angle for this 

 region alone. For the small degree of space charge which usually exists 

 between grid and plate of most triodes, 3/22 can be represented by a simple 

 capacitance. The transadmittance >'2i can be resolved into two factors, the 

 first of which depends only upon the transit angle between cathode and 

 grid, and the second only upon the transit angle between grid and anode. 

 In the paper on vacuum tube networks all these admittances were plotted 



