[time-nuts] Lucent GPSDO comments

Fri Nov 14 09:53:10 EST 2014

Hi

The people selling them do indeed stand behind the product. My only concern is making sure there really is a problem before something gets swapped out.

The best thing (by far) is to get a second unit and compare their outputs.

Bob

> On Nov 14, 2014, at 9:17 AM, paul swed <paulswedb at gmail.com> wrote:
> 
> Thanks everyone. My concern is did I need to reach out and get an exchange
> before the 30 days is up. I sense ASI the vendor is actually a pretty good
> company and will do the right thing.
> Regards
> Paul
> WB8TSL
> 
> On Fri, Nov 14, 2014 at 7:35 AM, Bob Camp <kb8tq at n1k.org> wrote:
> 
>> Hi
>> 
>> 
>> That OCXO is doing very well.
>> 
>> If you look at the plot, it’s doing a few LSB’s on the DAC over the time
>> period. That’s good performance.
>> 
>> Bob
>> 
>>> On Nov 13, 2014, at 9:17 PM, paul swed <paulswedb at gmail.com> wrote:
>>> 
>>> 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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>> side.GIF>_______________________________________________
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