We have observed narrowband plasma waves (≥0.1mV/m(Hz)1/2) at frequencies between the electron cyclotron frequency and the ambient plasma frequency. These waves are produced by the injection of a low-current electron beam (>3 mA). The frequency of these emissions is consistent with the diffuse resonances that have been observed by satellite-borne sounding experiments (Osherovich and Benson, 1991). These results were obtained from the rocket-borne experiment SCEX 3 (Several Compatible Experiments using a rocket-borne accelerator), NASA flight 39.002 UE, launched February 1, 1990, from Poker Flat Research Range (65.10¿N, 147.50¿W). These emissions are observed to propagate as far as 270 m across the ambient magnetic field with apparently little attenuation. These emissions are also observed up to 700 m from the accelerator along the electron beam. ¿ American Geophysical Union 1993