  The dynamical stability of nonstationary states of homogeneous spin-2
rubidium Bose-Einstein condensates is studied. The states considered are such
that the spin vector remains parallel to the magnetic field throughout the time
evolution, making it possible to study the stability analytically. These states
are shown to be stable in the absence of an external magnetic field, but they
become unstable when a finite magnetic field is introduced. It is found that
the growth rate and wavelength of the instabilities can be controlled by tuning
the strength of the magnetic field and the size of the condensate.
