Large-amplitude radio-frequency oscillations were discovered in high sheet-
resistance indium-indium-oxide films that carry nonuniform currents below t
he zero-field superconducting transition. The sample geometry consists of a
line that is oriented perpendicular to current flow inside a rectangular s
ection of the film. As the de current increases above a threshold, the volt
age spectrum displays several peaks which grow and shift toward higher freq
uencies. The effect is attributed to wave excitations in the density of cur
rent-depaired vortices and antivortices near the line tip.