Late evolution or an extended radio source is studied in the context o
f a simple model of magnetically driven expansion. The evolving radio
spectrum is calculated by accounting for synchrotron, Compton, and exp
ansion energy losses of relativistic electrons in the varying magnetic
field of the source. We estimate the Compton X-ray fluxes of the reli
cs 0924 + 30 and 1253 + 275, and conclude that the latter source is li
kely to be a dominant component of the high-energy flux from the Coma
region, if measured by a detector with a large field of view (such as
the OSSE on board the Compton Gamma Ray Observatory). We briefly discu
ss the possibility that steep-spectrum relics and diffuse radio source
s in clusters have a common origin.