730 



BELL SYSTEM TECHNICAL JOURNAL 



load si<];iials may occur as the result of direct pick-up of an adjacent radar 

 system or in certain cases atmospheric discharges. To prevent this a 

 mechanical shutter is inserted into the converter which offers effective 

 attenuation to any signal input. This shutter is withdrawn only if the 

 }>roper TR "keep alive" voltage is available. 



LOCAL oscillators: 



BEACON-1 r-RADAR 



waveguide - 

 (to magnetron) 



SCREEN CAP ON 



CONVERTER CRYSTAL 



JACK 



R-T Box/l-»^^i^H»r . ««iH|L. X 



.^WKml ,.' ..,. vtmmm "i r-t box 



i.r 



_..^^.»^_ - -T-RBOX 



T-R BOX ^BBfl^^^H^ 



-> -.,—-■ 



WAVEGUIDE "~f 



(to antenna) 



Fig. 23. — 10,000-mc Converter and IF j)reanii)lilk'r assemhl}' lor AN, Al'.S-4 airl)orne 

 radar ecjuipment. 



The performance characteristics of this converter and IF j)rcamp]iher 

 unit is as follows: 



Radar Frequency 10,000 mc 



IF Frequency 60 mc 



Conversion Loss . .' 6. 5 db 



Noise Figure of IF Preamplifier 4. 5 db 



Noise Figure of Converter 8. 6 db 



Noise Figure of Converter and Preamplifier 1 1 .9 db 



IF Hand Width 4 mc 



These values are rcpre.sentative of the performance under conditions of 

 average crystals and average IF iiijiut lubes. 



