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ILLINOIS STATE ACADEMY OF SCIENCE 



grid current curve. Fig. 8 is very interesting as it shows 

 that the potassium-sodium content tubes have high am- 

 plification constants even at high plate voltages, but that 

 they would function best as amplifiers at about 6 to 

 10 volts on the plate. The curves A and B, typical for 

 gas filled and vacuum tubes, should be noted for compari- 

 son. Fig. 9 shows how the potassium-sodium tubes be- 



have as detectors with varying plate voltages. Compar- 

 ing these curves with those of Fig. 2 it will be noticed that 

 the tubes containing potassium-sodium alloy are quite 

 remarkable. The best signal response is for plate volt- 

 ages of from 8 to 10 volts, or less than half of that neces- 

 sary for gas filled tubes, while they are much less criti- 

 cal than the latter, and give good audibility at 40 volts 



