  We investigate the properties of PbTe doped with a small concentration $x$ of
Tl impurities acting as acceptors and described by Anderson impurities with
negative onsite correlation energy. We use the numerical renormalization group
method to show that the resulting charge Kondo effect naturally accounts for
the unusual low temperature and doping dependence of normal state properties,
including the self-compensation effect in the carrier density and the
non-magnetic Kondo anomaly in the resistivity. These are found to be in good
qualitative agreement with experiment. Our results for the Tl s-electron
spectral function provide a new interpretation of point contact data.
