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ILLINOIS STATE ACADEMY OF SCIENCE 



for high vacuum amplifiers. Figure 6 shows grid cur- 

 rent characteristics for the same tube as used in obtain- 

 ing curves of Fig. 4. For negative grid voltages there is 

 no negative grid current, which is not the case for some 

 high vacuum tubes. The curves increase suddenly at 

 about -2 volts grid potential which indicates good de- 



tecting characteristics. It should be mentioned that the 

 detecting efficiency depends greatly upon the assymetry 

 or variation of the slope of this curve. (See page 456, 

 ** Principles of Radio Communication" by Morecroft.) If 

 the grid were connected to the positive end of the fila- 

 ment, the grid current would rise at zero grid voltage in- 

 stead of at -2 volts, but its slope would be the same. To 

 show how the tube constants vary with plate voltage the 



