Our recent measurements of positron lifetime (related to electron density at the annihilating sites) components or τi and Doppler broadening of positron annihilation radiation lineshape or S-parameter (denoting the fraction of low-momentum electrons among the annihilating electrons) on Bi-2212 and (Bi,Pb)-2223 pellets and Y-123 single crystals firstly confirm step-like changes across Tc. Our second and new observation is that S versus T graph in the superconducting transition region shows a double minimum for 2223 and 123 and a single minimum for 2212. These steps and minima, not seen for superconductors like Nb3Sn, are linked to such features of HTSC electronic structure as are not found in conventional superconductors.