  Electron holes are suggested to be an important source for generation of
electron-cyclotron maser radiation. We demonstrate that electron holes
generated in a ring-horseshoe distribution in the auroral-kilometric radiation
source region have the capacity to emit band-limited radiation. The radiation
is calculated in the proper frame of a circular model hole and shown to be
strictly perpendicular in this frame. Its bandwidth under auroral conditions is
of the order of $\sim1$ kHz, which is a reasonable value. {It is also shown
that much of the drift of fine structure in the radiation can be interpreted as
Doppler shift. Estimates based on data are in good agreement with theory.
Growth and absorption rates have been obtained for the emitted radiation.
However, the growth rate of a single hole obtained under conservative
conditions is small, too small for reproducing the observed fine structure
flux. Trapping of radiation inside the hole for the hole's lifetime helps
amplifying the radiation additionally but introduces other problems. This
entire set of questions is discussed at length and compared to radiation from
the global horseshoe distribution.} The interior of the hole produces a weak
absorption at slightly higher frequency than emission. The absorptivity is
roughly two orders of magnitude below the growth rate of the radiation thus
being weak even when the emission and absorption bands overlap. Transforming to
the stationary observer's frame it is found that the radiation becomes oblique
against the magnetic field. For approaching holes the radiated frequencies may
even exceed the local electron cyclotron frequency.
