444 BELL SYSILM TECIIS'IC.IL JOURNAL 



(^/>+2;;)(''/>+Zfe)(''p+S(;:-/c)) 



For rough calculations, n may be regarded as a constant. F'or 

 very careful work, this assumption should never be made without 

 first drawing the curves of id — Eg and iJL — Ep and verifying the va- 

 lidity of the assumption under operating conditions. Examples of 

 such curves are given in Fig. 2. When /jl may be regarded as constant, 

 and when the grid is maintained negative with respect to the filament, 

 (35) becomes 



_ — Ifjrrprp'ezih-k) 



which may be put into the form given in Mr. Carson's paper, referred 

 to before. 



The third and last component of (31) is that which produces grid 

 detection or modulation; namely 



ipih-k) = —ai(h-k)q{h-k)b2ih-k)e2{h~k) 



\rp+Z(h-k)) 2 L ^ '■ V V Tp+zJ \ vrp+Zk) 



P ~^dEp\v J\ (rp-^z,,) irp-\-Zk) J dE^ V p J 



fliZhTl f^kT/ _ yrrgHhZk \ n 

 \rp-\-Zh rp-\-Zk v{rp-}-Zh){rp-\-'zk)) J 



In using this relation, j' may nearly always be considered constant. 

 As grid leak detectors are often used, q consists of a resistance, Rg, 

 and a condenser, C, in parallel. The values of Rg and C are so ad- 



