  The observations of the two-periodic magnetic cataclysmic system EX Hya have
been carried out, using the telescopes RC16 and TOA-150 of the Tzec Maun
observatory. 6 nights of observations were obtained in 2010-2011 (alternatively
changing filters VR). Also the databases of WASP, ASAS and AAVSO have been
analyzed. Processing time series was carried out using the program MCV. We
analyzed changes in the rotation period of the white dwarf, and based on our
own and previously published moments of maximum. The ephemeris was determined
for the maxima of the radiation flux associated with the rotation of the
magnetic white dwarf: Tmax=2437699.89079(59)
+0.0465464808(69).E-6.3(2)*10^{-13}E^2, which corresponds to the characteristic
timescale of the rotation spin-up of 4.67(14)*10^6 years. This contradicts the
estimated value of the mass of the white dwarf of 0.42M_\odot, based on X-ray
observations made by Yuasa et al (2010), however, is consistent with estimates
of the masses of 0.79 M_\odot (white dwarf) and 0.108 M_\odot (red dwarf)
previously published Beuermann and Reinsch (2008), and the assumption that the
capture of accreted plasma by magnetic field of the white dwarf is near the
border of the Roche lobe. Analyzed moments do not support the assumption of
Mauche et al (2009) for a statistically significant cubic term in the
ephemeris. Despite the presence of outbursts in EX Hya, there are significant
differences from the DO Dra, which supports the introduction to a detailed
classification of the intermediate polars the groups of "outbursting
intermediate polars" and "magnetic dwarf novae."
