  The normal state and superconducting properties are investigated in the phase
diagram of K_xSr_{1-x}Fe_2As_2 for 0<x<1. The ground state upper critical
field, H_{c2}(0), is extrapolated from magnetic field dependent resistivity
measurements. H_{c2}(0) scales with the critical temperature, T_c, of the
superconducting transition. In the normal state the Seebeck coefficient is
shown to experience a dramatic change near a critical substitution of x=0.3.
This is associated with the formation of a spin density wave state above the
superconducting transition temperature. The results provide strong evidence for
the reconstruction of the Fermi surface with the onset of magnetic order.
