Re: Phase locking...
The problem is that if you have such frequency difference, in this case, 1Hz vs 10MHz, your clock must be less than 0.1ppm precize.
No clock can provide such precision, appart from Stratum 1 clock (Premium Clock), which can usually be obtained with more sophesticated equipments (ex: BITS derived from GPS signal).
Next, for such frequency difference, you'll need a very long lock time. I.e. it will take very long for the circuitry to be phased locked.