FLEXIBLE REPEATER DESIGN 



77 



The configuration of the beta circuit is shown in Fig. 8. In the pass 

 band it is a two terminal network whose impedance varies from about 

 300 ohms at 20 kc to 70 ohms at 164 kc. It consists of essentially two 

 parts. The elements to the left of the dotted line provide the major por- 

 tion of the shaping. With these the repeater is within ±0.7 db of the 

 required gain. The series resonant circuits to the right of the dotted line 

 reduce this to the ±0.05 db set as the objective. 



The mopping up elements are connected to the main portion of the 

 beta circuit through a resistance potentiometer Ri , R2 and R3 • This 

 scales the elements of the resonant circuits to values which would meet 

 mounting space and component restrictions. 



Built-in Testing Features 



The crystal Y and capacitor C, Fig. 1, in the feedback path provide the 

 means for checking the repeater from the shore station. The crystal is a 

 sharply tuned series-resonant shunt on the feedback path which reduces 

 the feedback at the resonant frequency and produces a narrow peak in 

 the insertion gain characteristic of the repeater. The feedback reduction, 

 and hence the peak gain, is controlled by the potentiometer divider 

 formed by the reactance of the capacitor and the series resonant resist- 

 ance of the crystal. The crystal and capacitor are chosen so that sub- 

 stantially all the feedback is removed from the repeater. With no feed- 



TO V3 HEATER 

 l+B) 



V3 PLATE FILTER 1 1 

 AND DC BLOCKING | I 

 CAPACITOR 



TO CATHODES 

 OF V„V2,V3 



TO GRID OF V, 



THROUGH HIGH SIDE 



OF INPUT COUPLING 



NETWORK 



AAAq^V\A— ^ 



1— r 



-wv 



TO PLATE OF V3 



THROUGH HIGH SIDE 



"of OUTPUT COUPLING 



NETWORK 



Fig. 8 — Beta network. 



