  The spin valve effect for the superconducting current based on the
superconductor/ferromagnet proximity effect has been studied for a
CoO_x/Fe1/Cu/Fe2/Cu/Pb multilayer. The magnitude of the effect $\Delta T_c$ =
T_c^{AP} - T_c^{P}, where T_c^{P} and T_c^{AP} are the superconducting
transition temperatures for the parallel (P) and antiparallel (AP) orientation
of magnetizations, respectively, has been measured for different thicknesses of
the Fe1 layer d_{Fe1}. The obtained dependence of the effect on d_{Fe1} reveals
that $\Delta T_c$ can be increased in comparison with the case of a
half-infinite Fe1 layer considered by the previous theory. A maximum of the
spin valve effect occurs at d_{Fe1} ~ d_{Fe2}. At the optimal value of d_{Fe1},
almost full switching from the normal to the superconducting state when
changing the mutual orientation of magnetizations of the iron layers Fe1 and
Fe2 from P to AP is demonstrated.
