Grid Currents in Three-Electrode Ionic Tubes. 133 



be further illustrated by considering the amplitude reached 

 by an impressed oscillation. Assume a sinusoidal E.M.F. 

 impressed on the inductance L. We then have 



L-~ + Hy — v = — JEi siu.Q)t, 



y + .^-G-gp 



i = K 1 Et. 

 These equations yield a solution 



v= Vsin (cot 4-0), .... 

 where TT E ft 



V*= 



►G 



s /(u+^ Kl J + ^ 



(6) 

 (?) 



l + zeiBA 2 

 coC ) 



From this it is clear that a positive grid conductance tends 

 to lower the effective electrostatic action of the grid at 

 resonance frequencies, but that with a negative conductance 

 amplification may occur. In the case of positive conductance 

 the maximum control action is again obtained when 







__A, A A 



In the case of an extremely hard valve the conductance is 

 positive for positive grid potentials and zero for all negative 

 values. Thus for an impressed oscillation the amplitude 

 reached for positive half oscillations is less than that reached 

 during negative halves. The difference can be got definitely 

 from (7), and gives a measure of the rectification obtained. 



Fig. 2. 



s N 



/ 



In ionic tube circuits for the generation of continuous 

 oscillations the oscillatory circuit is often connected between 

 the grid and the filament. A typical case is depicted in fig. 2. 



