65o Sketch 6 shows schematically the relationship of these major parts „ 



Linear 

 AoC Amplifier Rectifier D<,C g Amplifier 



6H6 

 Tubes 



n 



Sketch 6 - Schematic - P„Lo Graphic Level Recorder 



Magnetic 



Clutch 



System 



The function of the recorder is as follows When a signal voltage is im- 

 pressed across the input potentiometer it is amplified by the AC amplifier 

 and converted to pulsating DC by the linear rectifier., This variable' DC 

 voltage, after being further amplified by the DC amplifier, is impressed 

 across a bridge circuit which controls the current in the solenoids of the 

 magnetic clutch and energizes a train having the input potentiometer slider 

 at one end and the writing scriber at the other. The input potentiometer 

 functions to maintain the bridge in balance, thus causing the writing scriber 

 to follow signal input variations . The scriber engraves a record of its 

 movement across a waxed-paper tape 



66 „ Each Power Level graphic recorder uses the following tubes; 

 1 type 6R7, 2 type 6-N7* 2 type 6h6 s 1 type 6X5, 



2 type 6SF5 S 



TIME INDEXING MECHANISM 



67» The time indexing mechanism which is a part of each graphic level 

 recorder is so important to the successful operation of the monitor station 

 that the following section is devoted to its operation and adjustment „ 



17 - 



