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BELL SYSTEM TECHNICAL JOURNAL 



pears in the velocity factor M + iN. In the usual case some of the 

 alternating current flows to the grid wires and is returned through an 

 external circuit connected to the grid. If the impedance between grid 

 and plate is desired it is necessary to find the relation which this grid 

 current bears to the total cathode and plate currents and to the alter- 

 nating-current potentials. The calculations involved are extremely 

 complicated because the assumption of current flow in straight lines 

 between parallel planes is far from representing the actual conditions 



Q9 

 Q8 

 0.7 

 0.6 

 0.5 

 0.4 

 0.3 

 0.2 

 0.1 



1 2 3 4 5 6 7 8 9 10 11 12 



Fig. 10 — Plate impedance of positive grid triodes with slightly positive plate. 



in the immediate neighborhood of the grid wires. Rather than at- 

 tempting an analysis of these conditions at the present time, we shall 

 content ourselves with results already obtained, since they are appli- 

 cable to the special case, which can be realized approximately in experi- 

 ment, where the grid is connected to a radio-frequency choke coil of 

 sufficiently good characteristics to prevent it from carrying away any 

 alternating current. For this special case the current J\ is the same 

 both in the cathode region and in the plate region, and all encumbering 

 assumptions involving different paths for the conduction and displace- 



