The two-nucleon potential, with the necessary invariance requirements, is assumed to be a quadratic function of momentum: $v=\ensuremath{-}{V}_{0}{J}_{1}(r)\ensuremath{-}(\frac{\ensuremath{\lambda}}{M}) \mathrm{p}\ifmmode\cdot\else\textperiodcentered\fi{}{J}_{2}(r)\mathrm{p}$, where ${J}_{1}(r)$ and ${J}_{2}(r)$ are two short-range functions. For simplicity $\ensuremath{-}{J}_{2}(r)$ is assumed to be a square well of unit depth. The Schr\"odinger equation is solved (neglecting Coulomb forces) for three different choices of ${J}_{1}(r)$. Numerical results for the phase shifts are given for these three potentials (${v}_{1}, {v}_{2}, \mathrm{and} {v}_{3}$) for the singlet $S$, $D$, and $G$ states. Reasonably good fits are obtained.