— HEV TO SYMBOLS — 

 [u] LINE AMPLIFIER FOR OPEN WIHE 

 [ba| bridging AMPUFIEfi FOR OPEN WIRE 

 LINE AMPLIFIER FOR CABLE 

 MONITORING AMPLIFIER 



-ywC- VARIABLE ATTENUATOR 



^WV FIXED RESISTANCE LINE 



[l] LOW-FREQUENCT EQUALIZER 



HIGH- FREQUENCY EQUALIZER 



[nLc| NON-LOADED CABLE EQUALIZER 



[eI LOADED CABLE EQUAU2ER AND 

 '-' ASSOCIATED PHASE CORRECTDB ETC 



-ff" REPEATING COIL 



' ' REPEATING COIL WITH LINE WINDINGS 



J PARALLEL 

 [p] PREDISTORTING NETWORK 

 [r] RESTORING NETWORK 

 [i] 8000-CYCLE LOW-PASS LINE HLTER 



AUXILIARY 8000-CYCLE 

 LOW-PASS FILTER 



-<]] TWO-UNIT LOUD SPEAKER 



— <] SINGLE-UNIT LOUDSPEAKER 



f-nO SPECIAL HEADSET RECEIVERS AND 

 Cr*! ASSOCIATED NETWORK 



@ VOLUME INDICATOR 



NORMAL DIRECTION OF TRANSMISSION E-V 



USES X CONNECTIONS; REVERSED W-£. 



USES Y CONNECTIONS 



Fig. 20 — Circuit layout for trial of wide-band open-wire program system. 



