[time-nuts] Basic regenerative-divider questions

Bruce Griffiths bruce.griffiths at xtra.co.nz
Sat Sep 29 00:15:34 EDT 2007

John Miles wrote:
> Thanks much, Bruce.  I suspected either you or Enrico R. would have some
> knowledge of that.
> Note that I need to end up with 40 *and* 20 MHz, hence the plan to cascade
> two /2 dividers.  If there is a better topology for obtaining both of these
> outputs, it would be good to know.  I'd imagine that a /4 divider running
> alongside a /2 divider would be better from the additive-noise perspective.
> I will probably end up wanting a 10-MHz output as well.  The obvious
> question would be, should that be a separate F/8 + 7F/8 path, or a /2
> divider following the /4 divider?  I haven't seen many references to /8
> regenerative dividers but I suppose they'd be workable.  Availability of
> 8.75 MHz crystals might be what decides that question.
> -- john, KE5FX

What's the crystal for?
Crystal filters aren't usually necessary necessary.
A divide by 8 conjugate regenerative divider has been built and tested
by NIST.

In principle it would be possible to generate F/2, F/4 and F/8 outputs
simultaneously by adding parallel conjugate filtered feedback paths
tuned to 3F/2, 7F/8, 3F/4, F/2, F/4 and F/8.
However the difficulties associated with optimising the phase shifts and
gains of all the filtered feedback paths may be more trouble than its worth.


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