  In this study we attempt to assess the possibility of detection of variable
sources using the data of the 7.6-cm wavelength surveys carried out on the
RATAN-600 radio telescope in the period from 1980 through 1994. Objects
selected according to certain criteria from the RCR catalog are used to
construct the calibration curves and to estimate the accuracy of the resulting
calibration curves and determine the r.m.s. errors for the measured source flux
densities. To check the calibration sources for the presence of variable
objects, quantitative estimates are performed for a number of parameters that
characterize variability, in particular, for the long-term variability index V
and the chi-square probability p. The long-term variability index was found to
be positive for 14 out of approximately 80 calibration sources, possibly
indicating that these sources are variable. The most likely candidate variables
are the three sources with the chi-square probability p > 0.95. Five sources
have chi-square probabilities in the 0.85 < p < 0.95 interval, and the
remaining six in the 0.6 < p < 0.8 interval. Nine out of 14 objects are
possibly variable in the optical range. The light curves and spectra are
determined for possible variable sources and a number of "non-variable"
objects. We plan to use the results of this study in our future searches for
variable radio sources using the data of the "Cold" surveys.
