ADMITTANCES OF PARALLEL-PLANE ELECTRON TUBES 



637 



is in quadrature with tlic signal sidebands. The difference in phase between 

 the two adjustments of the phase shifter is equal to the phase between V i 

 and V <i . In measuring the transfer phase from Fi to Fo the output coaxial 

 line is terminated in its characteristic impedance. By reversing this pro- 

 cedure it is possible, of course, to measure the ratio of K2 to V i with the 

 input circuit terminated in Zo . The ratio of the magnitudes of V i and V 2 

 may be measured either with the eciuipment shown in Fig. 17 by adjusting 

 the phase of the homodyne carrier to maximize the signals in each case and 



OSCILLATOR 

 (4060 MC) 



PHASE SHIFTER 

 (CALIBRATED) 



KW'' 



VARIABLE 

 PHASE 



^ 



HYBRID 

 JUNCTION 



^ 



IH 



BALANCED 

 MODULATOR 



^mW^ 



pRRH- 



A-F 

 OSCILLATOR 



JIC 



V," 



^^+ 



Ml 



i 



=XZ) 



A-F 

 AMPLIFIER 



^ 



Zo 



TRANSFORMER GRID PLANE 



Fig. 17 — Circuit for measuring transfer phase of a triode. 



comparing the levels, or by using the equipment in Fig. 16 in the conven- 

 tional way. 



Figure 18 is a photograph of the triode circuit which shows the input and 

 output coaxial standing-wave detectors with the triode mounted in the 

 enlarged section at the center. 



As in the case of the diode it was found that, with the tube biased nega- 

 tively such that no electrons could leave the immediate vicinity of the 

 cathode, the input circuit exhibited an equivalent series resistance Rs. 

 The latter had to be allowed for in reducing the experimental data. 



