  RadioAstron satellite admits in principle a testing the gravitational
redshift effect with an accuracy of better than $10^{-5}$. It would surpass the
result of Gravity Probe A mission at least an order of magnitude. However,
RadioAstron's communications and frequency transfer systems are not adapted for
a direct application of the non relativistic Doppler and troposphere
compensation scheme used in the Gravity Probe A experiment. This leads to
degradation of the redshift test accuracy approximately to the level 0.01. We
discuss the way to overcome this difficulty and present preliminary results
based on data obtained during special observing sessions scheduled for testing
the new techniques.
