  We combine a light AsqTad antiquark with a nonrelativistic heavy quark to
compute the decay constants of heavy-light pseudoscalar mesons using the
ensemble of 3-flavor gauge field configurations generated by the MILC
collaboration. Preliminary results for $f_{B_s}$ and $f_{D_s}$ are given and
status of the chiral extrapolation to $f_B$ is reported. We also touch upon
results of the perturbative calculation which matches matrix elements in the
effective theory to the full theory at 1-loop order.
