  For the flavor-singlet heavy quark systems of quarkonia, we compute the
masses of the first radial excitation of mesons in four different channels:
pseudo-scalar ($\eta_{c,b}(2S)$), vector ($\psi (2S),\Upsilon(2S)$), scalar
($\chi_{c_0,b_0}(2P)$) and axial vector ($\chi_{c_1,b_{1}}(2P)$), as well as
the weak decay constants of the $\eta_{c,b}(2S)$ and $\psi (2S),\Upsilon(2S)$.
The framework for this analysis is provided by a symmetry-preserving
Schwinger-Dyson equations treatment of a vector$\times$vector contact
interaction. The results found for the meson masses are in good agreement
experimental data and earlier model calculations based upon Schwinger-Dyson and
Bethe-Salpeter equations (BSEs) involving sophisticated interaction kernels.
