Harold Johnson wrote:

I'm currently
using a SAW at 660 MHz for the clock in a 9951 DDS.

Interesting factoid: I was looking to experiment with 100MHz
oscillators largely as a clock source for my own AD9951 experimentation
(using the AD9951's built-in PLL multiplier at 4x). I was hoping to
experiment a bit with 20 MHz crystals I already had in hand before
ordering some "real overtone" crystals cut just for me. I've been
looking at AD app note AN-419 and it's Butler oscillator, in
particular, although the clock input of the AD9951 probably has
different requirements than the AD9850 targetted in AN-419.

Does the AD9951 really work at 660MHz? I thought it was only good to
400MHz...

So far my experimenting has used the on-chip oscillator at 25MHz and
the PLL at 16x to get to 400MHz.

Actually, it's better
than my 200 MHz 7th overtone tripled to 660

We bandied about "non-harmonic" relations here but how you get from 200
to 660, I don't know.

Tim.