ARMSTRONG, OPERATING FEATURES OF THE AUDION 223 



With the means at hand it was impossible to obtain the variations of 

 :grid potential directly, as the leak introduced by connecting the oscillo- 

 :graph to the grid would destroy the cumulative action. The grid poten- 

 tial, however, varies in exactly the same manner as the wing current. 

 The fundamental detecting action is, therefore, that of a valve, the high- 

 frequency oscillations being rectified between the filament and the grid 

 to charge the grid and the grid condenser. The charged grid then, ex- 

 erts a relay or* trigger action on the wing current, so that the audion 

 is at once a rectifier and an amplifier. A somewhat similar combination 



-incofr7,r>a Osc/Z/a^an 



^"y^s...9*f£CMit 



Conc/en. 



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Fig. 15 



of rectifying and amplifying actions occurs in the arrangement shown in 

 Fig. 7. The action of the audion is being further studied by Professor 

 Morecroft and the writer in the Hartley Eesearch Laboratory, Columbia 

 University, and the results of these investigations will soon be published. 



PAET II 



Some Eecent Developments of the Audion Eeceiver ^ 



It will be observed from the oscillogram of Fig. 15 that in addition to 

 the regular detecting phenomena the audion is simultaneously acting as 

 a repeater of the radio frequencies ; so that oscillations of the grid circuit 

 set up oscillations of similar character in the wing circuit of the audion. 

 In the ordinary detector system no use is made of the repeating action, 



2 Paper read before the Institute of Radio Engineei-s, New York, March 3, 1915, and 

 before the Boston Section, April 29, 1915. 



