MAGNETRON AS GENERATOR OF CENTIMETER WAVES 243 



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The conductance term, I — ) YocQo , is independent of frequency and the 



2 



susceptance term, 2Foc( j-^ ) varies hnearly with frequency. If 



Wo 



these quantities are plotted from experimental data as functions of co, the 



'if.) 



values of ^0 and! v> ) Foc may be determined. To determine the individual 



ii) 



values of the factors in I — j Yoc for a given magnetron, it is necessary to 



/C 1 



calculate or somehow to measure a value for Foc = /</ t = ^oC = 



L ojqL 



When used with wo this yields values for L, C, and M. How this is done 

 will not be explicitly discussed here. From the values of Qo and Yoc , 

 values oi Ql , Qe^t , and rjc may be calculated for any magnetron load Gl by 

 the relations (21), (22), (23), and (25). There are other methods of ex- 

 tracting the Q values from the experimental data than that presented above. 

 When values of the circuit parameters are available one can calculate the 

 values of Gg and Bs from which Ge and Be are obtained. From the output 

 power the RF voltage is then calculable by equation (38), and from this 

 and the electronic admittance the in-phase and quadrature components of 

 the RF current may be obtained. Using the circuit efl&ciency, rjc , now de- 

 termined as a function of load, one can obtain the dependence of the elec- 

 tronic efl&ciency, Tje , as a function of load conductance from experimental 

 values of the over-all efl&ciency, tj, measured along a constant frequency 

 contour of a Rieke diagram (rj = rjeVc)- The plot of Fig. 19 was ob- 

 tained in this way. One is now in possession of values for each of the param- 

 eters upon which the electronics of the magnetron depends and may 

 study the relations between them. 



9.4 Pulling Figure: The Rieke diagram completely specifies the 

 dependence upon load of the magnetron output power and frequency of opera- 

 tion. Nevertheless, it is convenient to be able to specify by a single para- 

 meter the dependence of operating frequency on load changes. The pre- 

 ceding discussion has shown that the changes in load conductance reflected 

 into the resonant circuit of the magnetron, that is, specified at either the 

 primary- or secondary terminals of the ideal transformer of Fig. 31 (b), vary 

 output power only. Further, if Ge and Be are unrelated, load susceptance 

 changes specified at the same points vary frequency only. Since 6% and 

 Bg are in fact related, constant frequency contours on the Gl — Bl plane, 

 as has been seen, are inclined to constant Bl lines at the angle a. Thus 

 changes in Bl are more eflfective by the factor 1/cos a in afifecting frequency 



