> I would have to look in the manual to be 100%, but for 90%, I think the "synchronize" button is just to synchronize the 1pps pulse with an external 1pps reference. It is a clock > (i.e., time) function NOT a frequency function. > The 5071A's are like that. Sync means align the PPSes and the 5MHz phase to be within a few nanos. Warner