We have carried out a systematic 6 3 Cu nuclear magnetic resonance (NMR) study on a set of ytterbium-based Kondo compounds YbXCu 4 with X=Au, Ag, In, Cd, Tl, and Mg. Splitting of the central NMR line due to a second-orderelectric-quadrupole interaction is of the order of magnitude of axial Knight shift, and the extent of splitting is controlled by changing applied field H. From the splitting of the central line, we have succeeded to deduce the values of both isotropic Knight shift K i s o and axial Knight shift K a x , taking a value of electric-quadrupole frequency determined by pure quadrupole resonance of 6 3 Cu, K i s o versus magnetic susceptibility Χ plots for each of the compounds with X=Au, Ag, and In are roughly on a straight line. For YbAgCu 4 (Kondo temperature T K ∼100 K), both K i s o and the unit-cell volume v c reach a local minimum around 40 K. We have found a linear relation between K i s o and v c below 100 K, similar to that observed in YbInCu 4 , indicating that the nonmagnetic behavior at low temperatures can be ascribed mainly to the Kondo volume expansion. In contrast, K i s o versus Χ plots for YbCdCu 4 (T K ∼220 K) and YbMgCu 4 (T K ∼860 K) exhibit somewhat complex behavior: hyperfine field H h f markedly increases coincident with the saturated behavior of Χ for X =Cd below ≃140 K, and with the decrease in Χ for X=Mg below ∼260 K. H h f originates mainly from transferred hyperfine coupling between Cu nucleus and Yb 4f moment, and the large increase in H h f is conjectured to result from a variation of crystal-electric-field interactions as the system transforms into a mixed-valence state. The variation with the species of X atoms of temperature-independent on-site contribution K s to the Knight shift is found to correlate with that of the electronic specific heat coefficient y (except for X=Cd), each of which gives a measure of the density of states of conduction sf resonance bands. Finally, using the values of K s , y, and T K , we have proposed a phase diagram for YbXCu 4 series, which corresponds to Doniach's phase diagram.