ABSTRACT Very low-noise measurements on an injected-beam crossed-field amplifier are discussed. Various considerations in the design of the low-power amplifier are discussed. The major factors in the achievement of low-noise measurements are the minimization of diocotron gain, use of a short Kino gun, introduction of a velocity-jump-type noise transformer and attenuation/elimination of the undesirable modes. The dependence of noise-figure value upon the various parameters is investigated. It is found that the effect of slight discrepancies in the values of one parameter can be compensated by proper adjustment of another suitable parameter. Broadbanding of the low-noise data is discussed. It is found that the uniformity of the line, good matches at the input/output transitions and a matched load are also necessary for low-noise results.