414 



THE BELL SYSTEM TECHNICAL JOURNAL^ APRIL 1951 



plain this circuit by saying that the output of class C amplifier is propor- 

 tional to the supply current. Two tubes, one a sort of audio amplifier and 

 one a class C amphfier, are connected in parallel to a single constant current 

 power supply consisting of a battery in series with a large inductor. The 



Fig. 26— Cathode modulator and dual. 



^§— viKHMy 



Fig. 27 — General balanced modulator and dual. 



class C amplifier can use only the current not used by the modulator tube, 

 and hence its output varies inversely with the plate current of, and hence 

 inversely with the grid voltage of, the modulator tube. The dual. Fig. 23(b), 

 consists of a class C transistor amplifier in series with a class A modulator 



