[time-nuts] Lucent GPSDO comments
kb8tq at n1k.org
Thu Nov 13 17:43:46 EST 2014
How much is your unit moving?
> 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.
> On Wed, Nov 12, 2014 at 7:21 PM, Bob Camp <kb8tq at n1k.org> wrote:
>> 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.
>>> 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
>>> 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
>>> 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
>>> all one has to do is remove or bypass the 15 MHz filter before the
>>> 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
>>> after the logic chips they use the same circuit.
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