VACUUM TUBES AS HIGH-FREQUENCY OSCILLATORS 127 



Negative Resistance Type 

 Data reported by McArthur and Spitzer ^ on a split-plate magnetron 

 tube are illustrative of the negative resistance type of behavior. 

 Static characteristics taken by varying the potential of one anode with 

 the magnetic field held constant for different values of the potential on 

 the other anode are shown in Fig. 26. The pronounced negative 



(J 5 



S 4 



1 2 3 4 5 6 7 8 9 10 II 12 13 14 



POTENTIAL ON ANODE SEGMENT "a" 



Fig. 26 — Static characteristics of a split-plate magnetron. 



resistance effect is obvious. This negative resistance characteristic 

 can be utilized in producing oscillations. 



Output and efificiency curves for this tube as an oscillator are shown 

 in Fig. 27. These data were obtained by connecting a "tank" 



h- 25 

 < 



z 20 



25 cc 



20 1 



50 75 100 125 150 175 200 225 250 275 300 325 350 375 400 

 FREQUENCY IN MEGACYCLES PER SECOND 



Fig. 27 — Output and efficiency curves at different frequencies for split-plate 



magnetron. 



