THE RADAR RECEIVER 749 



This equipment design features short and rigid connections and the use of 

 silvered-mica button-type by-pass elements which are mechanically an- 

 chored in slots cut into the chassis and soldered in place. The entire unit is 

 arranged to plug into a multipin socket which supplies all power and receives 

 the video signal output. The IF signal input is arranged for plug-in connec- 

 tion at the opposite end of the chassis. 



The adjustable inductance elements shown are wound on forms having an 

 approximate diameter of \" and the small variation in inductance required 

 to compensate for circuit variations is achieved by the use of tuning screws 

 as illustrated. These coils are adjusted in manufacture by a comparison 

 technique employing factory standards of the same form. The completed 

 amplifier is aligned with mean capacitance tubes and all tuning screws locked 

 and sealed. Sufficient design margin of gain has been included in this design 

 to enable meeting the radar system gain requirements with a complete set 

 of ''low-limit" tubes. 



2.3 The Radar Video Amplifier 



The video amplifier of the radar receiver, which follows the IF amplifier 

 and second detector, has as its function the final preparation of the received 

 and detected signal for display. This process involves amplification of the 

 signal in its now video form, introduction of additional coordinate signals 

 and wave forms required for proper display, and often includes modification 

 of the original amplitude characteristics of the signal itself to enhance the 

 presentation. The radar video signal is quite similar in many respects to the 

 television video signal and the circuit technology, therefore, parallels the 

 television art in many respects. Two characteristics of the radar video 

 signal result, however, in somewhat less stringent demands on the radar video 

 amplifier design. The lowest frequency of concern in radar video practice 

 is related to the repetition rate which rarely is found to be less than 250 pps., 

 while it is customary to design television systems to adequately transmit 

 signals of the order of 1 cps. The requirement of faithful reproduction of the 

 radar pulse shape is usually of secondary importance; the quality of presence 

 alone usually sufficing to meet the radar system design objective. In certain 

 fire-control radar systems, however, the radar system band width must be 

 adequate to reproduce the received pulse to an exactness of the order main- 

 tained in standard television practice. In general these somewhat reduced 

 transmission requirements for radar purposes result in a desirable economy 

 of circuit elements and power consumption. 



2.31 Gain-Frequency Consideralions 



The limiting performance of a video amplifier can conveniently be evalu- 

 ated by a consideration of the transmission problem at the extremities of the 



