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BELL SYSTEM TECUNICAL JOURNAL 



accordingly restricts the range of power frequencies over which satisfactory- 

 regulation and operation can be expected. With the emphasis on power 

 supply frequencies extending from 400 cps to 2400 cps for aircraft purposes, 

 this air insulated type of structure was abandoned in favor of oil immersed 

 types. The primary disadvantage of the oil immersed type of transformer 

 is the increased weight of the unit. 



A high-voltage power supply design as produced for airborne radar system 

 application is shown in Fig. 77. In this example +4900 volts is supplied 

 for cathode-ray tube indicator purposes and — 1000 volts is available for the 

 TR tube keep-alive circuit. This unit employs an air insulated type of 



Fig. 77. — High-voltage power supply for airborne radar receiver application— pressur- 

 ized type. 



high-voltage transformer and by the use of a hermetically sealed enclosure 

 operated at sea-level atmospheric pressure, satisfactory performance at high 

 altitudes is realized. 



Conclusion 



The complete technical story of radar is of a magnitude comparable to a 

 detailed report of the military campaigns of this past global war. During 

 this period, the Bell Telephone Laboratories developed for manufacture more 

 than 70 specialized radar systems for the Armed Services. It has been 

 possible here only to review the major technical considerations which in- 



