[time-nuts] HP10811 vs 00105 OCXO
Bob Camp
kb8tq at n1k.org
Sun Aug 9 12:08:28 UTC 2015
Hi
All 10811 OCXO’s have 10 MHz 3rd overtone SC cut crystals in them. They are the
first commercial (as opposed to military) OCXO to use the SC. The target was good
phase noise rather than good short term stability. They did quite well for the era in
terms of phase noise.
Back then and now, better short term designs exist. Also, then and now, the odd part
pops out of the batch that is a bit better than the rest. It is very rare to find
anybody with the ability to accurately test a good one who then decides to sell that OCXO.
Bob
> On Aug 8, 2015, at 7:21 PM, KA2WEU--- via time-nuts <time-nuts at febo.com> wrote:
>
> How good or bad is the 10811 and which one on ebay is a better choice ?
> I am looking for a very goo 5 MHz crystal oscillator with documentation .
>
> Thanks, Ulrich N1UL
>
>
> In a message dated 8/8/2015 7:16:37 P.M. Eastern Daylight Time,
> kb8tq at n1k.org writes:
>
> 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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