Buildup times and the stationary values of spin wave excitations near the Suhl instability threshold are calculated numerically. The study is done in the framework of the two-mode model. The time evolution of the excitation may approach the steady state via oscillations that may last for a very long time. The stationary excitation N0, and the buildup time τb depend on the pumping power p, and the pumping field h via power laws: N0=B(p/pc−1)δ and τb=A(h/hc−1)−Δ. For the case of no de-tuning of the mode frequencies from ωp/2, δ=0.5 and Δ=0.98. In the case of modes that are de-tuned from ωp/2, δ=0.42 and Δ=1.1. The values for δ are consistent with experiments but the values for Δ are in bad agreement with experiment. It is shown that if a finite medium correction term is introduced into the equations of motion the threshold of the pumping field amplitude is below γ/V where γ is the spin wave relaxation rate and V is the coupling of the spin waves to the pumping field. This result is very strange and raises serious doubts about the justification of the finite medium correction term.
