344 



KENNELLY AND UPSON— HUMMING TELEPHONE. 



[July 20, 



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Key 



O Good Transmiffers. 



K^ Down in Volume. 



O Thick Quolih/ 



O Burning. 



WOO 2000 3000 14000 3000 6000 7000 SOOO fOOO 10000 



RESISTANCE IN SECONDARY - OHMS. 



Fig. 7. Target Diagram of Transmitter Tests by the Method of Hum 

 Extinguishing Extra Resistance. 



60 



Fig. 



IZO MO /6a ISO zoo ZZO ZUO Z60 



TUBE LENGTH - CENTIMETERS. 

 8. Frequencies and Primary Currents for Different Primary E.M.F's. 



