A study was made at 4080 Mc of the partition noise introduced into a beam by a meshed grid as a function of its position along the beam. Simultaneous information concerning the beam dynamics was obtained by means of a beam analyzer. With cathode magnetic fields somewhat below those corresponding to immersed flow, the partition noise exhibited sharp dips as the grid in moving along the beam passed through the planes which corresponded to image planes of the cathode. These observations confirm the picture of noise smoothing taking place over relatively small areas in the vicinity of the cathode and elucidate the contribution of the random interception of electrons to the partition noise. With small cathode magnetic fields the partition noise varied sinusoidally with the cyclotron periodicity as the grid was moved along the beam. This variation with position is thought to result from the contribution to the partition noise of higher-order mode conversion.