  Inhomogeneities in a synchrotron source can severely affect the conclusions
drawn from observations regarding the source properties. However, their
presence is not always easy to establish, since several other effects can give
rise to similar observed characteristics. It is argued that the recently
observed broadening of the radio spectra and/or light curves in some of the
type Ib/c supernovae is a direct indication of inhomogeneities. As compared to
a homogeneous source, this increases the deduced velocity of the forward shock
and the observed correlation between total energy and shock velocity could in
part be due to a varying covering factor. The X-ray emission from at least some
type Ib/c supernovae is unlikely to be synchrotron radiation from an electron
distribution accelerated in a non-linear shock. Instead it is shown that the
observed correlation during the first few hundred days between the radio, X-ray
and bolometric luminosities indicates that the X-ray emission is inverse
Compton scattering of the photospheric photons. Inhomogeneities are consistent
with equipartition between electrons and magnetic fields in the optically thin
synchrotron emitting regions.
