REFLEX OSCILLATORS 



577 



are shown the power output, half power electronic tuning, and sink margin 

 as functions of frequency for the 7f cycle mode. 



F. Thermally Tuned Reflex Oscillators — -The ZK45 



The trend toward the simplification of radar systems to the fewest possible 

 adjustments, coupled with the ever present possibility of enemy jamming, 

 led to the attempt to produce a system which was described as a single knob 

 system. The ultimate objective of such a system was ability to shift the 

 frequency of the transmitter at will with a single control. This puts the 

 chief burden on the receiver, which must automatically track with the 



REQUIRED RANGE- 



8800 9000 9200 9400 9600 



FREQUENCY IN MEGACYCLES PER SECOND 



Fig. 74. — Variation of electronic tuning, power output and sink margin with frequency 

 for the 2K25 in a repeller mode having 15.5 ir radians drift. Characteristic admittance 

 load and coupling of Fig. 70. 



transmitter. The problem is much simplified by designing as many of the 

 components as possible so that retuning is not required when the frequency 

 is shifted within the requisite band. In the case of the beating oscillator 

 it was necessary to devise a mechanism which would permit rapid automatic 

 control over a frequency range of 1160 mc. This range was many times in 

 excess of any immediately realizable electronic tuning range. It is of course 

 apparent that such a method of tuning will also lend itself readily to use in 

 many apphcations in which, although the transmitter frequency is nominally 

 fixed, the system is required to operate under such extreme conditions that 

 the sum total of the possible frequency deviations is in excess of the available 



