REFLEX OSCILLATORS 



477 



will just start and no power output will be obtained. We can state the 

 general condition for stable operation as 1% + Fc = 0, where Y c is the 

 vector sum of the load and circuit admittances. For the optimum drift 

 time this becomes 



Gc 



ye 



2/i(X) 

 X 



(3.10J 



0.1 0.2 0.3 0.4 0.5 6 0.7 0.8 0,9 10 



ye 



Fig. 9. — EiEciency parameter U vs the ratio of load conductance to the magnitude of 



the small signal electronic admittance. Curves are for various ratios of resonator loss 



conductance to small signal electronic admittance. The curves are of similar shapes and 



indicate that the tube will cease oscillating {U = 0) when loaded by a conductance about 



h' ice as large as that for optimum power. 



where 



ye 



Gl + Gr 



(3.11) 



G c 



Hence for a given value of — we may assume values for — between zero 



ye ye 



Q 



and 1 — — and these in (3.11) will define values of X. These values of X 



ye ^ 



substituted in (3.7) will define values of H which we then plot against the 

 assumed values for — , as in Fig. 9. Thus we have the desired function of 



ye 



the variation of efhciency factor against load. 



