The measurements of the joule heat loss relaxation in the form of the power loss relaxation Q( tau ) of the microwave cavity, with a sample excited at the quasi-free electron spin precession frequency (9.5 GHz) and on cooling the sample from room temperature to 77 K, have been reported. It is found that the microwave resonance relaxation absorption (MRRA) spectra near T_c observed for the sample exhibit the SC phase transition based on the temperature DC resistance measurements.