206 



BELL SYSTEM TECHNICAL JOURNAL 



made on the fader. The ampHfier shown consists of three units. 

 The first consists of three low power tubes in tandem, resistance 

 coupled, and requiring a 12-volt battery delivering 1/4 ampere to heat 

 their filaments. The second consists of a single stage of two medium 

 power tubes, connected in push-pull arrangement with filaments 



