FLEXIBLE REPEATER DESIGN 



75 



builds out the leakage inductance of the transformer and together with 

 capacitor Cs controls the shaping at the top end of the band. These ele- 

 ments are adjusted during manufacture of the networks to provide the 

 desired shaping. 



The equivalent circuit is an approximation to the true transformer 

 circuit. By standard network analysis techniques the ratio V/Ei , the 

 gain of the network, can be obtained. The agreement between measure- 

 ments and computation is sufficiently close, several hundredths of a db, 

 to insure that the representation is good. 



Each coupling network is designed to provide approximately one- 

 third of the total shaping required, or 13 db. While these networks are 



32 

 30 

 26 

 26 



^24 

 U 



ai 



Q 22 



? 20 

 < 



18 



16 3 



14 



12 



10 



20 40 60 80 100 200 400 600 1000 



FREQUENCY IN KILOCYCLES PER SECOND 



Fig. 6 — Gain of input coupling network. 



outside the feedback path, the impedances which they present to the 

 amplifier are important factors in the feedback design. It can be seen 

 from Fig. 3 that at the amplifier input the proportion of the feedback 

 voltage which will be effective in producing feedback around the loop 

 is dependent upon the potentiometer division between the grid-cathode 

 impedance of the first tube and the impedance looking back into the 

 coupling network. The greater the gain shaping of the network, the 

 greater the potentiometer loss. The maximum gain which can be ob- 

 tained from the coupling network is limited by the capacitance across 

 the circuit. This capacitance cannot be reduced without increasing the 



