Hi Walter,
The crystal I'm referring to is the Crystek CVHD-950-122.88 VCXO.
Currently it's connected to the circuit, and that will limit the output frequency range that
you want to have by changing RefA/B.
If you can get a 123.5 MHz crystal, to replace it, you will be able to get to 247MHz ADC clock.
Also I was told that maybe removing the clock completely, and use the ref A/b to generate the clock without a crystal might also work.
The clock will not be as clean as when you have a crystal set to your frequency of interest.
Charly