[time-nuts] Lucent GPSDO comments

paul swed paulswedb at gmail.com
Fri Nov 14 02:17:48 UTC 2014


Bob the actual pictures and files are large so here is the left screen and
right screen from the z3811 program. Pretty easy to guess whats in the
middle.
Lots of noise on the ti/pps and you can see EFC is rising all the time.
I will say in the past it had been a steady rise now there is a wave that
might mean its slowing down a bit.
But this all looks rattier then I would believe.
Regards
Paul
WB8TSL


On Thu, Nov 13, 2014 at 5:43 PM, Bob Camp <kb8tq at n1k.org> wrote:

> Hi
>
> How much is your unit moving?
>
> Bob
>
> > On Nov 13, 2014, at 1:50 PM, paul swed <paulswedb at gmail.com> wrote:
> >
> > On the older units that used a RB to control an Xtal. They created a mix
> of
> > 5 Mhz +10 Mhz and that produced 15 out that hit an amplifier to drive a
> 12
> > way splitter.
> > I think I reverse engineered the circuit. Its on paper and filed. Oh that
> > ends this discussion.
> > Anyhow it was not hard to figure out.
> > I am still baking my Lucent in so want to see if it settles.
> > There is just the barest of hints it may be.
> >
> > So do not want to power down to explore. Happy to dig in if I don't have
> to
> > return the unit.
> >
> > Regards
> > Paul
> > WB8TSL
> >
> > On Wed, Nov 12, 2014 at 7:21 PM, Bob Camp <kb8tq at n1k.org> wrote:
> >
> >> Hi
> >>
> >> The chain in the Z3810 / 3811 / 3812 Lucent boxes is *much* different
> than
> >> the setup in the earlier parts. The phase noise and ADEV on the Z3810’s
> is
> >> better than what you got on the earlier versions. That makes keeping the
> >> noise down in whatever mod you do more important. The existing 10 MHz
> >> output on the Z3810 setup is a real good example of how a seemingly
> simple
> >> thing can add a lot of phase noise and even mess up ADEV.
> >>
> >> I don’t think the 15 MHz is used for much of anything in the Z3810. That
> >> could be wrong, but I can’t see where it is needed based on poking
> around a
> >> little. The 15 MHz buffer appears to be quiet and puts out a lot of
> power.
> >> Using it for 10 MHz would give you a *lot* of 10 MHz signal to play
> with.
> >> IF the mods are simple it’s an attractive solution. If it involves
> swapping
> >> out 30 parts - not so much.
> >>
> >> Bob
> >>
> >>> On Nov 12, 2014, at 5:50 PM, Perry Sandeen via time-nuts <
> >> time-nuts at febo.com> wrote:
> >>>
> >>> Wrote: At some point we will get into hacking the main board
> >>> to switch from 15 MHz to 10 MHz.
> >>>
> >>> One doesn’t have to that if one uses the two IC divide by
> >>> 1.5 circuit I offered the list. I specifically found it so I didn’t
> have
> >> to
> >>> hack the innards.
> >>>
> >>> Wrote: The great news is the oscillator is 5 Mhz.
> >>>
> >>> Don’t bet the rent on that. My early units have 10 MHZ Datum
> >>> oscillators.
> >>>
> >>> Bob’s point about getting the GPSDO’s if all cost the same
> >>> is a good point.
> >>>
> >>> Another point. At least on the older units I have: GPSDO,
> >>> Rubidium, and Crystal oscillator, the output circuitry after the 15 MHz
> >>> conversion takes place is the same. So if one hacks the 10 Mhz into the
> >> chain,
> >>> all one has to do is remove or bypass the 15 MHz filter before the
> >> output.
> >>>
> >>> Even if you don’t have the rubidium unit but have either/or
> >>> GPDO or Crystal oscillator email me off list for the rubidium schematic
> >> as
> >>> after the logic chips they use the same circuit.
> >>>
> >>> Regards,
> >>>
> >>> Perrier
> >>> _______________________________________________
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> >>> and follow the instructions there.
> >>
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