The results and experimental details ofS‐band noise figure and noise spectra measurements made on electron beams that yield traveling‐wave‐tube noise figures below 4 dB are presented. A simple technique involving the observation of the change in noise figure with electron gun‐helix separation in a special traveling‐wave tube (TWT) is employed. A positive correlation between current and velocity fluctuations contributes heavily to the reduction of noise in the ultralow‐noise TWT. This conclusion supports the general results, but not necessarily the details of the theory of noise on multivelocity beams. In contrast to the theoretical assumption that the important source of multivelocity flow is the cathode temperature, the measurements give evidence that, in the ultralow‐noise TWT, the flow of importance is due to transverse beam slippage in the finite beam that produces what may be termed a ``quasi‐multivelocity'' flow with a velocity spread which may be wide enough to mask the thermal spread. The measurements also raise the possibility that a cyclotron wave‐space‐charge wave interaction occurring beyond the cathode‐first anode space contributes to the noise behavior.