That the noise convection current in a diode would be the same as the noise current in a triode under the conditions θ1≫1 and θ2≪1 (θ1 and θ2 are transit angles in radians of the potential minimum-to-grid and grid-to-plate regions, respectively) is shown by following the approach indicated by Rack and applying the Llewellyn-Peterson small signal theory to study the noise in a triode. Although the general trend of the experimental results agrees very well with the prediction from the Rack approach, the measured value of noise power is found to be about 2 db below the predicted value. The experimental results are applicable to triodes as well under certain conditions.