Dynamic autocorrelation functions for 2.56-ms adjusted intervals of single pulses of PSR 0809+74 have been analyzed. The observations were conducted at 102.5 MHz with 10μs resolution. We find that the neighboring 2.56-ms subpulse intervals seem to have independent microstructure parameters, although sometimes the tendency was observed for the occurrence of quasi-periodic structures of close or double periods within the same subpulse. The distribution of a number of well ordered micropulses in quasi-periodic structures was shown to agree with the hypothesis of a random origin of quasi-periodicities. No relation has been found between the microstructure parameters and subpulse longitude.