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BELL SYSTEM TECHNICAL JOURNAL 



lator a reaction from some modulation product back into the signal 

 impedance is less and less as the product becomes of higher order, or as 

 the circuit loss to it becomes greater. Where the impedances of the 

 connected circuits have bothersome interactions with the copper 

 oxide impedance either at the signal frequencies or the lower loss 

 modulation products, resistance pad separation is usually the simplest 

 solution if the increased loss can be tolerated. 



400 



350 



300 



250 



200 



150 



50 



-50 



uj-lOO 

 O 



-200 



-250 



60 



65 70 75 80 85 90 95 



INPUT FREQUENCY IN KILOCYCLES PER SECOND 



100 



105 



Fig. 5 — Impedance of a representative double-balanced modulator. 



Energy losses in copper oxide modulators between signal input and 

 single sideband signal output have been found to be no greater than 

 8 or 9 db even at frequencies of 3 or 4 megacycles. At lower fre- 

 quencies 5 or 6 db losses are normal, but losses as low as 2 db have been 



