This paper presents the first results of rapid scan Doppler spectra of the diffuse radar aurora obtained with the Homer 398-MHz phased array radar. Each spectrum was obtained from three consecutive 1-ms radar pulses spanning an interval of 0.04 s. The spectral resolution obtainable with these short samples was improved by using a maximum entropy method of spectral analysis. Most of the results obtained from the postmidnight period and were characterized by relatively narrow spectra having Doppler velocities which were nearly constant over an extended azimuth sector (referred to as a Doppler velocity plateau). Typically, there is a positive plateau to the west and a negative plateau to the east, separated by a small or nonexistent transition region; this situation exactly parallels the observations in the equatorial electrojet of 'Type 1' irregularities, and it is likely that these velocity plateaus arise from the same mechanism. In addition, transition spectra are observed which tend to be broader and have Doppler shifts intermediate between those of the positive and negative plateaus. In contrast to previous observations of the evening diffuse radar aurora these transition spectra were not localized in one azimuth sector. A unique feature of the observations was the occurrence of double-peaked spectra, the Doppler velocities of the two peaks usually corresponding to the positive and negative plateau velocities. These last two observations, and also other evidence, can be understood as a consequence of an irregular auroral electrojet.