  We consider the production of chargino and charged Higgs boson pairs at
future linear colliders for c.m. energies in the one TeV range. Working in the
MSSM under the assumption of a "moderately" light SUSY scenario, we compute the
leading (double) and next-to leading (linear) supersymmetric logarithmic terms
of the so-called "Sudakov expansion" at one loop. We show that a combined
analysis of the slopes of the chargino and of the charged Higgs production
cross sections would offer a simple possibility for determining $\tan\beta$ for
large ($\gtrsim 10$) values and an allowed strip in the ($M_2,\mu$) plane. This
could provide a strong consistency test of the considered supersymmetric model.
