ADMITTANCES OF PARALLEL-PLANE ELECTRON TUBES 



639 



The experimental data obtained as described above were suHicient for 



computing the four-pole parameters. The calculations necessary for the 



reduction of the data can best be understood by referring to Fig. 19. The 



various symbols used in connection with the figure are defined as follows: 



Yi = Normalized admittance measured at 1-1 with 2-2 shorted 



F2 = Normalized admittance measured at 2-2 with 1-1 shorted 



V'l 



TZff = 721 (measured with output line terminated in Zo) 



y 2 



The above parameters represent those obtained by the measurements 



described above. 



m, m2 2 



Fig. 19 — Equivalent circuit of Iriode and associated measuring equipment. 



In calibrating the circuit the following parameters were obtained: 

 Pi = ordinate intercept of input cot-cot curve 

 p-2 = ordinate intercept of output cot-cot curve 



>ni = slope of input cot-cot curve 



ni-2 — slope of output cot-cot curve 



Pi „ P2 



Bqi = — ; 



Brn = 



66 Wi ""' 66 W2 



Zo = characteristic impedance of input and output coaxial lines. 

 Rs was measured by shorting the output line, placing a large negative bias 

 on the tube, and measuring the admittance of the input line. Then 



Rs = 66}niRe{Y{) 



(6) 



where the number 66 represents the characteristic impedance of the coaxial 



line used in calibrating the input circuit, corresponding to Zox: in Equation 4. 



Fortunately for simplicity, the series resistance in the output circuit 



(7) 

 (8) 



