[Lowfer] Has anybody tried...

[John Andrews]

Art,

> I also mentioned the marginal .02 Hz frequency steps and commented that I
> wished they had built a AD9854 unit, giving many more features and sub
> millihertz frequency steps.

I don't see anything in the 9850 design that precludes finer frequency
steps. It's really a choice of the designer who selects the clock frequency.
I'm using a 4.294... MHz clock which gives exact 1 milliHertz steps. The
lower clock limit on the 9850 is 1 MHz, so there's room for at least 0.5 mHz
increments.

Just be aware that if you throw a 10 MHz clock on a 9850, you will have
round-off errors in the integer math that may be significant if you're
concerned about milliHertz. That's why I use two 9850's, the first to go
from 10 MHz to 4.294... MHz, and the second for the actual LF output.

John Andrews