  We report a high-$T$ Ga-NMR study in the kagome-based antiferromagnetic
compound SrCr$_{9p}$Ga$_{12-9p}$O$_{19}$ ($.81\leq p\leq .96$), and present a
refined mean-field analysis of the high T local NMR susceptibility of Cr
frustrated moments. We find that the intralayer kagome coupling is $J=86(6)$ K,
and the interlayer coupling through non-kagome Cr moments is $J^{\prime
}=69(7)$ K. The $J^{\prime}/J=0.80(1)$ ratio confirms the common belief that
the frustrated entity is a pyrochlore slab.
