REFLEX OSCILLATORS 



569 



conductor or may be arranged so that the condenser serves simultaneously 

 as an impedance transformer to transform the impedance of the line to that 

 required for best performance of the oscillator. A general discussion of 

 the problems involved in such coupling designs will be given in a later sec- 

 tion. 



One of the primary considerations in the design of a reflex oscillator is 

 the choice of resonator characteristics. The various controlling factors 

 have been outlined in previous sections. In Section X it was shown that 

 the power output and the electronic tuning optimize at different gap transit 



O" 



LU LU 

 10> 



40 Lut 





y UJ 



zo 



DO. 



z< 



3500 3600 3700 3800 



FREQUENCY IN MEGACYCLES PER SECOND 



Fig. 69. — Power output and electronic tuning vs frequency for the 2K29 reflex oscillator 

 The solid lines give the performance into a load adjusted for optimum power output at 

 each frequency. The dashed lines show the performance obtained when the tube is 

 coupled to a 50 ohm load by means of the fitting of Fig. 68. 



angles. It is therefore necessary to compromise with the ultimate use in 

 mind. In a beating oscillator for a radar receiver, uniformity of the elec- 

 tronic tunmg is of greater importance than uniformity of power output, 

 since an adjustment of the coupling to the crystal permits some variation 

 of the latter quantity. Hence, the resonator characteristics are chosen to 

 provide as nearly uniform electronic tuning as possible. Fig. 69 shows the 

 electronic tuning and power output characteristics for the Western Electric 

 2K29 tube. These are shown for two conditions. The solid lines show the 

 power output and electronic tuning measured into an adjustable load which 



