DSO751SA75.000MHZ DSO751SA8.000MHZ DSO751SA80.000MHZ DSO751SB 12.288MHz DSO751SB 16.000MHZ DSO751SB 20.048MHz DSO751SB 20.800MHZ DSO751SB 24.000MHZ DSO751SB 27.120MHZ DSO751SB 3.2768MHz