EXPERIMENTAL TRANSVERSAL EQUALIZER FOR TD-2 



1445 



the middle coupler, the fourth port of which is terminated in 75 ohms 

 and the third port connected to the summing network. 



The envelope delay in the cables connecting each coupler to the rheo- 

 stat and to the summing network appears as delay for the particular 

 echo path. Since these delays are not negligible compared to the 25 milli- 

 microsecond delay between echos, the cable lengths were controlled so 

 that the same amount of additional delay was introduced into each path 

 including the main path. 



XI. ADJUSTMENT AND PERFORMANCE 



After the eciualizer was assembled, the length of each of the cables 

 connecting the couplers to the summing network was adjusted so that 



Fig. 11 — Equalizer with cover removed. Calile.s wound out.-^ide frame are the 

 delay line sections. Summing network and directional couplers are in center. Rheo- 

 stat cases are mounted on panel with coaxial connection in rear. 



