It is not just a 2 Mhz offset that you have to change.? The oscillator is used to set the internal pll s in the 5351, and different divider ratios have to set depending on the oscillator frequency.? All si5351 libraries and code I have seen have a place to set the oscillator frequency to either 27 or 25 Mhz.?? In the NT7S library there is also a calibration adjustment that can be applied to make small adjustments to account for any slight difference in? crystal frequency
DuWayne KV4QB
DuWayne Schmidlkofer