Using Kirchhoff's law to calculate grid bias

One must take into account the already existing typically -700mV between grid and cathode (even before anode voltage is applied) by the missing electrons from cathode to space charge leaving the cathode positive or the grid negative.


The sum of all potentials round a closed loop must be zero.


This also applies when the Pleiades bias is applied from anode to grid and we can calculate by Ohm's law the external current from grid to anode. See previous post.


Is this a current that does not induce noise, or induces minimal noise?


Practice shows that the behaviour of the electron tube is ultra low noise.


So perhaps this current may remove influence from the sensitive cathode space charge grid area.


At the same time this Pleiades or anode bias increases gain at just 3V anode potential. Increases anode current, reduces plate or anode resistance, increases transconductance. And of course therefore in practice reduces noise or increases the signal to noise ratio.