The Nature of the Uncorrelated Component of Induced Grid Noise

An investigation of induced grid noise in vacuum tubes has been made. It was found that the uncorrelated component of grid noise can be explained in terms of electrons elastically reflected from the plate of the tube. Experimental and theoretical justifications of this explanation are presented. The accuracy of methods for predicting grid noise from measurements of input admittance is affected because of a component of input admittance arising from reflected electrons. A table is included showing typical (measured) values of the induced grid noise of eleven modem receiving tubes.