[time-nuts] HP10811 vs 00105 OCXO

[Bob Camp]

Hi

Ok, so John’s observation was the correct one. The data we are looking at is *not* the
performance of the OCXO’s but the strange behavior of the counter at short ADEV Tau’s. 

Sorry for my bashing your poor 10811.

Bob

> On Aug 8, 2015, at 12:25 PM, timeok at timeok.it wrote:
> 
> Hi all,
> 
> I try to ansver to all you:
> 
> Luciano, how was the blue trace taken? Is this from your DMTD project? If so, it's looking promising.
> The green and magenta traces are definitely in the right ballpark for measurements on a 5370-class counter. At 3E-11 @ t=12s the magenta trace is optimistic but not outrageously so, while the green trace looks exactly like I'd expect for a typical 10811 measured on a 5370. The observed noise is due entirely to the counter until about t=200s. We see a glimpse of the 10811's typical ADEV at about 250 seconds, just before either drift or ADEV uncertainty causes the trace to turn upwards. A longer run would be needed to distinguish between these two situations.
> 
> -- john, KE5FX
> Miles Design LLC
> 
> r: no, all the measurements are taken using an HP53132A  in frequency mode. The difference can be the gate time. Using 1 second the resolution is lower than using 2 Second that permit the max counter  resolution.
> 
> Hi
> 
> Well an un-stated assumption of mine was that they all came from the same measurement system and that it
> had the same floor under all circumstances….
> 
> Bob
> 
> r: all the measurements are under the same conditions except for the gate time of the counter.
> 
> Hi Luciano,
> 
> Can you give me the link to your ADEV posting image about 10811 vs 105 oscillators?  I had it and now can't seem to find it.  I wanted to look at your plots as I read John Miles' comments.  Many thanks.  
> 
> I have two very high performing HP10811-60109 OCXO units which I got from Corby. 
> 
> Many thanks.
> 
> Jim Robbins
> N1JR
> 
> r: Jim, I will load soon some files on my site. The 105B I have is a fantastic exception, unfortunately it have a defect, may be a bad  solder inside cause randomly a phase jump and return to the original phase trend, so all The long term ADEV are distorted by this problem I have to fix.
> 
> Tom VB, i will do all the cross measurements on 10811, 00105 and rubidium I have and i will upload they but I need time to do this.
> Unfortunately I have only the HP53132A as TIC and my best reference are four HP5065A. I normally use the counter function because the TI function on 1 PPS have 100 time less resolution.
> Will be interesting doing also the Phase noise tests. I will do it.
> please see: http://www.timeok.it/files/time_and_frequency_house_standard_201r.pdf
> 
> Luciano
> www.timeok.it
> 
> 
> 
> 
> 
> On Sat 08/08/15 02:23 , Bob Camp <kb8tq at n1k.org> wrote:
> 
>> Hi
>> 
>> Well an un-stated assumption of mine was that they all came from the same
>> measurement system and that it
>> had the same floor under all circumstances….
>> 
>> Bob
>> 
>>> On Aug 7, 2015, at 5:21 PM, John Miles  wrote:
>>> 
>>>> Hi
>>>> 
>>>> If that data is correct, then the 10811 you have is defective.
>>>> Bob
>>> 
>>> Well... some of the data is reasonable for a scenario where a counter is
>> being used to measure OCXOs.
>>> 
>>> Looking at the ADEV plot, I'd say the blue trace (HP105B vs 5065A) is
>> the most questionable one if it came from a standalone TIC or frequency
>> counter, because 7E-12 @ t=1s isn't achievable with most counters under
>> most circumstances. A Wavecrest box can measure at that level if it's set
>> up _perfectly_ to take bursts of 100+ wrap-free averages within a small
>> fraction of the t0 interval. It might also be doable with an HP 5370A/B
>> under similar conditions, but I'd have less confidence that the averaging
>> isn't distorting the measurement. So while It looks like a valid
>> measurement of an OCXO with some minor crosstalk or other external
>> interference, that may just be a coincidence.
>>> 
>>> Luciano, how was the blue trace taken? Is this from your DMTD project?
>> If so, it's looking promising.
>>> 
>>> The green and magenta traces are definitely in the right ballpark for
>> measurements on a 5370-class counter. At 3E-11 @ t=12s the magenta trace is
>> optimistic but not outrageously so, while the green trace looks exactly
>> like I'd expect for a typical 10811 measured on a 5370. The observed noise
>> is due entirely to the counter until about t=200s. We see a glimpse of the
>> 10811's typical ADEV at about 250 seconds, just before either drift or ADEV
>> uncertainty causes the trace to turn upwards. A longer run would be needed
>> to distinguish between these two situations.
>>> 
>>> -- john, KE5FX
>>> Miles Design LLC
>>> 
>>> 
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