REFLEX OSCILLATORS 



475 



Thus, the curves illustrate the variation of power from mode to mode as the 

 repeller voltage is changed over a wide range. 



Changes in resonator loss or differences in loss between individual tubes 

 of the same type correspond to passing from a curve for one value of K to a 

 curve for another value of K. 



0.50 

 0.40 



E 



I 



qT 0.10 



o 



t3 0.08 



< 



u. 

 >0.06 



g 0.05 

 o 



,7 0.04 



LU 



0.03 



0.05 



0.1 



ye 



Fig. 7. — Efficiency factor Hm vs the ratio of resonator loss conductance to the small 

 signal electronic admittance. Efficiency changes rapidly with load as the loss conductance 

 approaches in magnitude the small signal electronic admittance. The efficiency is in- 

 versely proportional to the number of cjxles drift. 



It will be observed from this that although, from an efficiency standpoint, 

 it is desirable to work at low values of drift time such low drift times lead 

 to an output strongly sensitive to changes in resonator losses. 



Perhaps the most important question which the user of the oscillator may 

 ask with regard to power production for optimum drift is; what effect does 

 the external load have upon the performance? If we couple lightly to the 

 oscillator the r-f voltage generated will be high but the power will not be 

 extracted. If we couple too heavily the voltage will be low, the beam will 

 not be efficiently modulated and the power output will be low. There is 



