Re: [time-nuts] Z380XA The saga of the aging 10811

[Bob Benward]

In a few weeks I will be posting another plot.  After the EFC slope drift
reversal from positive to negative, it is now starting to flatten again and
it looks like it will be again reversing and going positive again.  Starting
to look sinusoidal.

Bob


>>> -Original Message-
>>> From: time-nuts [mailto:time-nuts-boun...@febo.com] On Behalf Of James
>>> Flynn
>>> Sent: Friday, September 25, 2015 10:40 AM
>>> To: time-nuts@febo.com
>>> Subject: Re: [time-nuts] Z380XA The saga of the aging 10811
>>> 
>>> Bob Benward <rbenward@...> writes:
>>> 
>>> >
>>> > Continuing this discussion, I have included a PDF showing the past
>>> 30days of
>>> > EFC.  Amazingly, the drift has reversed direction!  Anyone have any
>>> insights
>>> > into this behavior?  Each data point represents 10 seconds.
>>> >
>>> 
>>> I have found that three things can cause this behavior over a short term
>>> (days) which do not involve failure of the standard itself ( in no
particular
>>> order ):
>>> 
>>> 1) Power supply. Most standards are immune to this but, if your EFC
circuit or
>>> phase detector involves active circuits, it can show up.
>>> 
>>> 2) Grounds. Bad grounds or ground loops, especially those that share
current
>>> with the oven heater can cause unexplained drift. However, these usually
>>> have a diurnal temperature signature unless your set up is very climate
>>> controlled. Screw terminal grounds or connections can "age" and change
>>> things. Best to ahve everything soldered.
>>> 
>>> 3) Cheap components, especially resistors. I recently had this driving
me nuts.
>>> Carbon comp. and the 2 cent metal film resistors have large temperature
>>> coefficients and are even sensitive to humidity. Go for the <10ppm / deg
C
>>> metal film or SMD resistors. Some caps also can be tricky if the circuit
>>> involves large caps.  Leakage is a problem in high impedance circuits
and can
>>> be unpredictable and non-constant.
>>> 
>>> Finally, there is literature that supports resonators can reverse their
ageing
>>> slope. However, this is rare.
>>> 
>>> I hope this helps.  I have been there, scratching my head while the
system
>>> seems to have a mind of its own.
>>> 
>>> ___
>>> time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to
>>> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
>>> and follow the instructions there.
>>> -
>>> No virus found in this message.
>>> Checked by AVG - www.avg.com
>>> Version: 2015.0.6140 / Virus Database: 4419/10665 - Release Date:
>>> 09/19/15

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Re: [time-nuts] Z380XA The saga of the aging 10811

[James Flynn]

Bob Benward  writes:

> 
> Continuing this discussion, I have included a PDF showing the past 
30days of
> EFC.  Amazingly, the drift has reversed direction!  Anyone have any 
insights
> into this behavior?  Each data point represents 10 seconds.
> 

I have found that three things can cause this behavior over a short term 
(days) which do not involve failure of the standard itself ( in no 
particular order ):

1) Power supply. Most standards are immune to this but, if your EFC 
circuit or phase detector involves active circuits, it can show up.

2) Grounds. Bad grounds or ground loops, especially those that share 
current with the oven heater can cause unexplained drift. However, these 
usually have a diurnal temperature signature unless your set up is very 
climate controlled. Screw terminal grounds or connections can "age" and 
change things. Best to ahve everything soldered.

3) Cheap components, especially resistors. I recently had this driving 
me nuts. Carbon comp. and the 2 cent metal film resistors have large 
temperature coefficients and are even sensitive to humidity. Go for the 
<10ppm / deg C metal film or SMD resistors. Some caps also can be tricky 
if the circuit involves large caps.  Leakage is a problem in high 
impedance circuits and can be unpredictable and non-constant.

Finally, there is literature that supports resonators can reverse their 
ageing slope. However, this is rare.

I hope this helps.  I have been there, scratching my head while the 
system seems to have a mind of its own.

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Re: [time-nuts] Z380XA The saga of the aging 10811

[Attila Kinali]

On Tue, 22 Sep 2015 23:49:25 -0400
"Bob Benward"  wrote:

> Continuing this discussion, I have included a PDF showing the past 30days of
> EFC.  Amazingly, the drift has reversed direction!  Anyone have any insights
> into this behavior?  Each data point represents 10 seconds.

Vig and Meeker have written a good paper on aging of quartz crystals[1],
which lists quite of few of the aging mechanisms and references papers
that have studied them. If you cannot access it, a (very short) summary
can be found in Vig's Crystal Oscillator Tutorial [2].


Attila Kinali


[1] "The Agin of Bulk Acoustic Wave Resonators, Filters and Oscillators",
by Vig, Meker, 1991

[2] 
http://ko4bb.com/manuals/index.php?dir=02_GPS_Timing/John_Vig_Tutorials_on_Crystal_Oscillators

-- 
Reading can seriously damage your ignorance.
-- unknown
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Re: [time-nuts] Z380XA The saga of the aging 10811

[Bob Camp]

Hi


> On Sep 22, 2015, at 11:49 PM, Bob Benward <rbenw...@verizon.net> wrote:
> 
> Continuing this discussion, I have included a PDF showing the past 30days of
> EFC.  Amazingly, the drift has reversed direction!

Yes, it’s fairly common. The standard advice with OCXO’s is to leave them on 
power as much as you possibly can.  

A bit more detailed explanation:

You have multiple processes that contribute to aging. They each have different 
rates, and
directions. Most of them follow a exponential decay. On a crummy oscillator, 
you may have 
one really terrible process that dominates everything. On a good part, you will 
see reversals 
and multiple slopes.

Bob

>  Anyone have any insights
> into this behavior?  Each data point represents 10 seconds.
> 
> Bob
> 
>>>> -Original Message-
>>>> From: time-nuts [mailto:time-nuts-boun...@febo.com] On Behalf Of Magnus
>>>> Danielson
>>>> Sent: Tuesday, September 22, 2015 5:46 PM
>>>> To: time-nuts@febo.com
>>>> Cc: mag...@rubidium.se
>>>> Subject: Re: [time-nuts] Z380XA The saga of the aging 10811
>>>> 
>>>> Analog is nice and dandy, but for longer time-constants, digital does
> have it's
>>>> merits.
>>>> 
>>>> Wonder how good resolution one really need for sensing and how to
> achieve
>>>> it.
>>>> 
>>>> Cheers,
>>>> Magnus
>>>> 
>>>> 
>>>> On 09/15/2015 12:58 PM, Bob Camp wrote:
>>>>> Hi
>>>>> 
>>>>> To the extent that the oven controller is an integrator, it only
>>>>> integrates over a couple of seconds.
>>>>> 
>>>>> Bob
>>>>> 
>>>>>> On Sep 14, 2015, at 5:58 PM, Bob Benward <rbenw...@verizon.net>
>>>> wrote:
>>>>>> 
>>>>>> Robert,
>>>>>> The drift has slowed down to something around 8xE-10, which is a bit
>>>>>> over the spec of <5E-10.  But this is the single oven, I have not
>>>>>> reassembled the double oven yet.
>>>>>> 
>>>>>> If the oven regulation was off, I would suspect I would see the EFC
>>>>>> go back and forth a bit, maybe a general trend up, but some retracing
>>>>>> would be expected.  The oven control is an integrator, so unless the
>>>>>> offset is very large compare to the output of the thermistor, a
>>>>>> continuously changing offset voltage will not have a large effect on
>>>>>> setpoint.  A crystal resonator will drift about 1-5E-8/degC, so I
>>>>>> guess a loose temperature control would certainly exhibit the drift I
> am
>>>> seeing.
>>>>>> 
>>>>>> Bob
>>>>>> 
>>>>>> 
>>>>>> 
>>>>>>>>> -Original Message-
>>>>>>>>> From: time-nuts [mailto:time-nuts-boun...@febo.com] On Behalf Of
>>>>>>>>> George Atkinson
>>>>>>>>> Sent: Monday, September 14, 2015 2:42 PM
>>>>>>>>> To: Discussion of precise time and frequency measurement
>>>>>>>>> Subject: Re: [time-nuts] Z380XA The saga of the aging 10811
>>>>>>>>> 
>>>>>>>>> Well, if the batch/revision of op-amps had a doping, contamination
>>>>>>>>> or
>>>>>> similar
>>>>>>>>> issue, the input offset could be drifting fairly constantly
>>>>>>>>> causing a temperature channge in one direction.
>>>>>>>>> 
>>>>>>>>> Robert G8RPI.
>>>>>>>>> 
>>>>>>>>> On 9 September 2015 at 04:40, Bob Benward
>>>> <rbenw...@verizon.net>
>>>>>>>>> wrote:
>>>>>>>>> 
>>>>>>>>>> Hi Ed,
>>>>>>>>>> OK, a bad oven.  I can buy that.  But then if the oscillator is
>>>>>>>>>> constantly drifting, would that not imply that the oven is
>>>>>>>>>> constantly changing temperature, in one direction?
>>>>>>>>>> 
>>>>>>>>>> BTW, the curve is starting to flatten out.  It might be flat
>>>>>>>>>> before It gets to 1000K counts.
>>>>>>>>>> 

Re: [time-nuts] Z380XA The saga of the aging 10811

[Magnus Danielson]

Analog is nice and dandy, but for longer time-constants, digital does 
have it's merits.


Wonder how good resolution one really need for sensing and how to 
achieve it.


Cheers,
Magnus


On 09/15/2015 12:58 PM, Bob Camp wrote:

Hi

To the extent that the oven controller is an integrator, it only integrates 
over a couple
of seconds.

Bob


On Sep 14, 2015, at 5:58 PM, Bob Benward <rbenw...@verizon.net> wrote:

Robert,
The drift has slowed down to something around 8xE-10, which is a bit over
the spec of <5E-10.  But this is the single oven, I have not reassembled the
double oven yet.

If the oven regulation was off, I would suspect I would see the EFC go back
and forth a bit, maybe a general trend up, but some retracing would be
expected.  The oven control is an integrator, so unless the offset is very
large compare to the output of the thermistor, a continuously changing
offset voltage will not have a large effect on setpoint.  A crystal
resonator will drift about 1-5E-8/degC, so I guess a loose temperature
control would certainly exhibit the drift I am seeing.

Bob




-Original Message-
From: time-nuts [mailto:time-nuts-boun...@febo.com] On Behalf Of George
Atkinson
Sent: Monday, September 14, 2015 2:42 PM
To: Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] Z380XA The saga of the aging 10811

Well, if the batch/revision of op-amps had a doping, contamination or

similar

issue, the input offset could be drifting fairly constantly causing a
temperature channge in one direction.

Robert G8RPI.

On 9 September 2015 at 04:40, Bob Benward <rbenw...@verizon.net>
wrote:


Hi Ed,
OK, a bad oven.  I can buy that.  But then if the oscillator is
constantly drifting, would that not imply that the oven is constantly
changing temperature, in one direction?

BTW, the curve is starting to flatten out.  It might be flat before It
gets to 1000K counts.

Bob


-Original Message-
From: time-nuts [mailto:time-nuts-boun...@febo.com] On Behalf Of
ed breya
Sent: Tuesday, September 08, 2015 10:55 AM
To: time-nuts@febo.com
Subject: Re: [time-nuts] Z380XA The saga of the aging 10811

It could be that the inner oven temperature regulation is off a
bit, or

even

failed. There was a report at one of the popular time-nuts
oriented

websites (I

forget which one, but it's the one that had extensive coverage of
the

Z3801A)

about inner oven problems a few years ago. I took mine apart and
found

that

it had an IC of a particular date code range that was prone to

failure.

I can't

recall whether I replaced it with the same type but different
date, or

an

alternative, but it worked just fine after that, with no tweaking
of

coarse EFC

needed.

The IC was a dual opamp I think, that controlled the oven
temperature according to the thermistor signal, and drove the

heater

transistor(s).

It was a fairly high performance type, but not that unusual. I
think it

was a

Linear Technology brand part.

Ed
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09/14/15


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Re: [time-nuts] Z380XA The saga of the aging 10811

[Bob Camp]

Hi

To the extent that the oven controller is an integrator, it only integrates 
over a couple
of seconds. 

Bob

> On Sep 14, 2015, at 5:58 PM, Bob Benward <rbenw...@verizon.net> wrote:
> 
> Robert,
> The drift has slowed down to something around 8xE-10, which is a bit over
> the spec of <5E-10.  But this is the single oven, I have not reassembled the
> double oven yet.
> 
> If the oven regulation was off, I would suspect I would see the EFC go back
> and forth a bit, maybe a general trend up, but some retracing would be
> expected.  The oven control is an integrator, so unless the offset is very
> large compare to the output of the thermistor, a continuously changing
> offset voltage will not have a large effect on setpoint.  A crystal
> resonator will drift about 1-5E-8/degC, so I guess a loose temperature
> control would certainly exhibit the drift I am seeing.
> 
> Bob
> 
> 
> 
>>>> -Original Message-
>>>> From: time-nuts [mailto:time-nuts-boun...@febo.com] On Behalf Of George
>>>> Atkinson
>>>> Sent: Monday, September 14, 2015 2:42 PM
>>>> To: Discussion of precise time and frequency measurement
>>>> Subject: Re: [time-nuts] Z380XA The saga of the aging 10811
>>>> 
>>>> Well, if the batch/revision of op-amps had a doping, contamination or
> similar
>>>> issue, the input offset could be drifting fairly constantly causing a
>>>> temperature channge in one direction.
>>>> 
>>>> Robert G8RPI.
>>>> 
>>>> On 9 September 2015 at 04:40, Bob Benward <rbenw...@verizon.net>
>>>> wrote:
>>>> 
>>>>> Hi Ed,
>>>>> OK, a bad oven.  I can buy that.  But then if the oscillator is
>>>>> constantly drifting, would that not imply that the oven is constantly
>>>>> changing temperature, in one direction?
>>>>> 
>>>>> BTW, the curve is starting to flatten out.  It might be flat before It
>>>>> gets to 1000K counts.
>>>>> 
>>>>> Bob
>>>>> 
>>>>>>>> -Original Message-
>>>>>>>> From: time-nuts [mailto:time-nuts-boun...@febo.com] On Behalf Of
>>>>>>>> ed breya
>>>>>>>> Sent: Tuesday, September 08, 2015 10:55 AM
>>>>>>>> To: time-nuts@febo.com
>>>>>>>> Subject: Re: [time-nuts] Z380XA The saga of the aging 10811
>>>>>>>> 
>>>>>>>> It could be that the inner oven temperature regulation is off a
>>>>>>>> bit, or
>>>>> even
>>>>>>>> failed. There was a report at one of the popular time-nuts
>>>>>>>> oriented
>>>>> websites (I
>>>>>>>> forget which one, but it's the one that had extensive coverage of
>>>>>>>> the
>>>>> Z3801A)
>>>>>>>> about inner oven problems a few years ago. I took mine apart and
>>>>>>>> found
>>>>> that
>>>>>>>> it had an IC of a particular date code range that was prone to
> failure.
>>>>> I can't
>>>>>>>> recall whether I replaced it with the same type but different
>>>>>>>> date, or
>>>>> an
>>>>>>>> alternative, but it worked just fine after that, with no tweaking
>>>>>>>> of
>>>>> coarse EFC
>>>>>>>> needed.
>>>>>>>> 
>>>>>>>> The IC was a dual opamp I think, that controlled the oven
>>>>>>>> temperature according to the thermistor signal, and drove the
> heater
>>>> transistor(s).
>>>>>>>> It was a fairly high performance type, but not that unusual. I
>>>>>>>> think it
>>>>> was a
>>>>>>>> Linear Technology brand part.
>>>>>>>> 
>>>>>>>> Ed
>>>>>>>> ___
>>>>>>>> time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to
>>>>>>>> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
>>>>>>>> and follow the instructions there.
>>>>>>>> -
>>>>>>>> No virus found in this message.
>>>>>>>> Checked by AVG - www.avg.com
>>>>>>>> Version: 2015.0.6140 / Virus Database: 4409/10580 - Release Date:
>>>>>>>> 09/05/15
>>>>> 
>>>>> ___
>>>>> time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to
>>>>> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
>>>>> and follow the instructions there.
>>>>> 
>>>> ___
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>>>> Checked by AVG - www.avg.com
>>>> Version: 2015.0.6140 / Virus Database: 4419/10639 - Release Date:
>>>> 09/14/15
> 
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Re: [time-nuts] Z380XA The saga of the aging 10811

[Bob Benward]

Robert,
The drift has slowed down to something around 8xE-10, which is a bit over
the spec of <5E-10.  But this is the single oven, I have not reassembled the
double oven yet.

If the oven regulation was off, I would suspect I would see the EFC go back
and forth a bit, maybe a general trend up, but some retracing would be
expected.  The oven control is an integrator, so unless the offset is very
large compare to the output of the thermistor, a continuously changing
offset voltage will not have a large effect on setpoint.  A crystal
resonator will drift about 1-5E-8/degC, so I guess a loose temperature
control would certainly exhibit the drift I am seeing.

Bob



>>> -Original Message-
>>> From: time-nuts [mailto:time-nuts-boun...@febo.com] On Behalf Of George
>>> Atkinson
>>> Sent: Monday, September 14, 2015 2:42 PM
>>> To: Discussion of precise time and frequency measurement
>>> Subject: Re: [time-nuts] Z380XA The saga of the aging 10811
>>> 
>>> Well, if the batch/revision of op-amps had a doping, contamination or
similar
>>> issue, the input offset could be drifting fairly constantly causing a
>>> temperature channge in one direction.
>>> 
>>> Robert G8RPI.
>>> 
>>> On 9 September 2015 at 04:40, Bob Benward <rbenw...@verizon.net>
>>> wrote:
>>> 
>>> > Hi Ed,
>>> > OK, a bad oven.  I can buy that.  But then if the oscillator is
>>> > constantly drifting, would that not imply that the oven is constantly
>>> > changing temperature, in one direction?
>>> >
>>> > BTW, the curve is starting to flatten out.  It might be flat before It
>>> > gets to 1000K counts.
>>> >
>>> > Bob
>>> >
>>> > >>> -Original Message-
>>> > >>> From: time-nuts [mailto:time-nuts-boun...@febo.com] On Behalf Of
>>> > >>> ed breya
>>> > >>> Sent: Tuesday, September 08, 2015 10:55 AM
>>> > >>> To: time-nuts@febo.com
>>> > >>> Subject: Re: [time-nuts] Z380XA The saga of the aging 10811
>>> > >>>
>>> > >>> It could be that the inner oven temperature regulation is off a
>>> > >>> bit, or
>>> > even
>>> > >>> failed. There was a report at one of the popular time-nuts
>>> > >>> oriented
>>> > websites (I
>>> > >>> forget which one, but it's the one that had extensive coverage of
>>> > >>> the
>>> > Z3801A)
>>> > >>> about inner oven problems a few years ago. I took mine apart and
>>> > >>> found
>>> > that
>>> > >>> it had an IC of a particular date code range that was prone to
failure.
>>> > I can't
>>> > >>> recall whether I replaced it with the same type but different
>>> > >>> date, or
>>> > an
>>> > >>> alternative, but it worked just fine after that, with no tweaking
>>> > >>> of
>>> > coarse EFC
>>> > >>> needed.
>>> > >>>
>>> > >>> The IC was a dual opamp I think, that controlled the oven
>>> > >>> temperature according to the thermistor signal, and drove the
heater
>>> transistor(s).
>>> > >>> It was a fairly high performance type, but not that unusual. I
>>> > >>> think it
>>> > was a
>>> > >>> Linear Technology brand part.
>>> > >>>
>>> > >>> Ed
>>> > >>> ___
>>> > >>> time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to
>>> > >>> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
>>> > >>> and follow the instructions there.
>>> > >>> -
>>> > >>> No virus found in this message.
>>> > >>> Checked by AVG - www.avg.com
>>> > >>> Version: 2015.0.6140 / Virus Database: 4409/10580 - Release Date:
>>> > >>> 09/05/15
>>> >
>>> > ___
>>> > time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to
>>> > https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
>>> > and follow the instructions there.
>>> >
>>> ___
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>>> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
>>> and follow the instructions there.
>>> -
>>> No virus found in this message.
>>> Checked by AVG - www.avg.com
>>> Version: 2015.0.6140 / Virus Database: 4419/10639 - Release Date:
>>> 09/14/15

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Re: [time-nuts] Z380XA The saga of the aging 10811

[George Atkinson]

Well, if the batch/revision of op-amps had a doping, contamination or
similar issue, the input offset could be drifting fairly constantly causing
a temperature channge in one direction.

Robert G8RPI.

On 9 September 2015 at 04:40, Bob Benward <rbenw...@verizon.net> wrote:

> Hi Ed,
> OK, a bad oven.  I can buy that.  But then if the oscillator is constantly
> drifting, would that not imply that the oven is constantly changing
> temperature, in one direction?
>
> BTW, the curve is starting to flatten out.  It might be flat before It gets
> to 1000K counts.
>
> Bob
>
> >>> -Original Message-
> >>> From: time-nuts [mailto:time-nuts-boun...@febo.com] On Behalf Of ed
> >>> breya
> >>> Sent: Tuesday, September 08, 2015 10:55 AM
> >>> To: time-nuts@febo.com
> >>> Subject: Re: [time-nuts] Z380XA The saga of the aging 10811
> >>>
> >>> It could be that the inner oven temperature regulation is off a bit, or
> even
> >>> failed. There was a report at one of the popular time-nuts oriented
> websites (I
> >>> forget which one, but it's the one that had extensive coverage of the
> Z3801A)
> >>> about inner oven problems a few years ago. I took mine apart and found
> that
> >>> it had an IC of a particular date code range that was prone to failure.
> I can't
> >>> recall whether I replaced it with the same type but different date, or
> an
> >>> alternative, but it worked just fine after that, with no tweaking of
> coarse EFC
> >>> needed.
> >>>
> >>> The IC was a dual opamp I think, that controlled the oven temperature
> >>> according to the thermistor signal, and drove the heater transistor(s).
> >>> It was a fairly high performance type, but not that unusual. I think it
> was a
> >>> Linear Technology brand part.
> >>>
> >>> Ed
> >>> ___
> >>> time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to
> >>> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> >>> and follow the instructions there.
> >>> -
> >>> No virus found in this message.
> >>> Checked by AVG - www.avg.com
> >>> Version: 2015.0.6140 / Virus Database: 4409/10580 - Release Date:
> >>> 09/05/15
>
> ___
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Re: [time-nuts] Z380XA The saga of the aging 10811

[ed breya]

It could be that the inner oven temperature regulation is off a bit, or 
even failed. There was a report at one of the popular time-nuts oriented 
websites (I forget which one, but it's the one that had extensive 
coverage of the Z3801A) about inner oven problems a few years ago. I 
took mine apart and found that it had an IC of a particular date code 
range that was prone to failure. I can't recall whether I replaced it 
with the same type but different date, or an alternative, but it worked 
just fine after that, with no tweaking of coarse EFC needed.


The IC was a dual opamp I think, that controlled the oven temperature 
according to the thermistor signal, and drove the heater transistor(s). 
It was a fairly high performance type, but not that unusual. I think it 
was a Linear Technology brand part.


Ed
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Re: [time-nuts] Z380XA The saga of the aging 10811

[Bob Benward]

Hi Ed,
OK, a bad oven.  I can buy that.  But then if the oscillator is constantly
drifting, would that not imply that the oven is constantly changing
temperature, in one direction?

BTW, the curve is starting to flatten out.  It might be flat before It gets
to 1000K counts.

Bob

>>> -Original Message-
>>> From: time-nuts [mailto:time-nuts-boun...@febo.com] On Behalf Of ed
>>> breya
>>> Sent: Tuesday, September 08, 2015 10:55 AM
>>> To: time-nuts@febo.com
>>> Subject: Re: [time-nuts] Z380XA The saga of the aging 10811
>>> 
>>> It could be that the inner oven temperature regulation is off a bit, or
even
>>> failed. There was a report at one of the popular time-nuts oriented
websites (I
>>> forget which one, but it's the one that had extensive coverage of the
Z3801A)
>>> about inner oven problems a few years ago. I took mine apart and found
that
>>> it had an IC of a particular date code range that was prone to failure.
I can't
>>> recall whether I replaced it with the same type but different date, or
an
>>> alternative, but it worked just fine after that, with no tweaking of
coarse EFC
>>> needed.
>>> 
>>> The IC was a dual opamp I think, that controlled the oven temperature
>>> according to the thermistor signal, and drove the heater transistor(s).
>>> It was a fairly high performance type, but not that unusual. I think it
was a
>>> Linear Technology brand part.
>>> 
>>> Ed
>>> ___
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>>> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
>>> and follow the instructions there.
>>> -
>>> No virus found in this message.
>>> Checked by AVG - www.avg.com
>>> Version: 2015.0.6140 / Virus Database: 4409/10580 - Release Date:
>>> 09/05/15

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Re: [time-nuts] Z380XA The saga of the aging 10811

[Charles Steinmetz]

Bob wrote:


So the simple answer is - no, a double oven (or boosted
single oven) will not age worse than a single oven.


Additionally, the outer heater on many commercially-available "double 
oven" OCXOs -- including the DO 10811s -- is not on during normal 
operation.  It is only there to get the inner oven up to temperature 
quickly, then it cuts out.  This allows the inner heater to be 
designed for lower output and finer temperature control, without 
taking forever to warm up to operating temperature.


Best regards,

Charles



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Re: [time-nuts] Z380XA The saga of the aging 10811

[Bill Hawkins]

Interesting.

There may be a use for the OCXO units in the old Lucent boxes with the
insensitive GPS receivers.

The OCXO is an Efratom part # 023005-001. Some of those boxes were never
used.

Google can't find the specifications for the XO. I expect they're not as
good as a functioning 10811, but they're better than a bad one if you've
become attached to your Z38xx.

Alternatively, you could try an LPRO-101 Rubidium with EFC if you don't
need the short term stability of a crystal. The EFC loop tuning
constants might be different, though.

Either Lucent box can be shipped (in the USA) in a USPS large Fixed Rate
Priority Mail box for $18.

Bill Hawkins



-Original Message-
From: time-nuts [mailto:time-nuts-boun...@febo.com] On Behalf Of Bob
Benward
Sent: Saturday, September 05, 2015 1:19 PM
To: Time Nuts
Subject: [time-nuts] Z380XA The saga of the aging 10811

Hi All,

I would like to convey the saga of my Z3801A and my Z3805A.

I purchased a Z3801A a few years ago at the Dayton Hamfest.  I got it
running and a few months later the unit lost it's GPS lock.  I did some
trouble shooting and finally realized the unit ran out of EFC range.  I
opened the double oven 10811 and retuned the unit to the lower end.  The
unit ran for another year or so, and then the oscillator died.  The
frequency was close, but the amplitude dropped too low for the circuitry
to lock on to.  I put the Z3801A aside and purchased a Z3805A from China
(I think from Yixunhk).

-%<-

On another tangent, I tried hooking up a Morion to the Z3805A.  I used
an inverting amplifier for the EFC since the coefficient is positive and
on the
10811 is negative.  I never achieved good control before the Morion
itself died.  I will probably continue working on marrying a new OCXO to
the Z380XA control board.  I need an alternate source for the OCXO
without depending on used double oven 10811s.


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Re: [time-nuts] Z380XA The saga of the aging 10811

[Bob Camp]

Hi

The “stuff’ that should contribute to aging on an OCXO is all packed away with
the crystal inside the oven. The frequency is sensitive to it so you heat it 
for 
stability. 

The temperature of the oven that the crystal is in, is a function of the 
crystal it’s self. 
It does not matter if it’s a double oven, single oven, or triple oven. What 
ever the final 
oven in the chain, it will be at the crystal’s magically determined sweet spot 
temperature. 

So the simple answer is - no, a double oven (or boosted single oven) will not 
age 
worse than a single oven. The only case that’s not true is when either of the 
ovens 
fails and runs away. That result is not generally called aging, it’s usually 
called melt down …

Bob


> On Sep 5, 2015, at 2:19 PM, Bob Benward  wrote:
> 
> Hi All,
> 
> I would like to convey the saga of my Z3801A and my Z3805A.
> 
> 
> 
> I purchased a Z3801A a few years ago at the Dayton Hamfest.  I got it
> running and a few months later the unit lost it's GPS lock.  I did some
> trouble shooting and finally realized the unit ran out of EFC range.  I
> opened the double oven 10811 and retuned the unit to the lower end.  The
> unit ran for another year or so, and then the oscillator died.  The
> frequency was close, but the amplitude dropped too low for the circuitry to
> lock on to.  I put the Z3801A aside and purchased a Z3805A from China (I
> think from Yixunhk).
> 
> 
> 
> I plugged in the Z3805A and it ran for a few years.  One day, a few days
> after a relatively active thunderstorm, I notice the alert light was on and
> I had lost GPS lock.  I thought a close strike wiped out the GPS receiver.
> After a lot of screwing around, I figured out that the 10811 had also lost
> EFC range.  The output voltage sat at the neg2.0V level and would not budge.
> I opened up the 10811 and readjusted the tuning to put the EFC counts at
> below 100K.  I never reassembled the oscillator, I just left it sprawled out
> on the table.  Checking the EFC stats, it started with a relatively high
> 1E-8 per day of drift.  It has since calmed down to 5E-9, and you can see a
> slight flattening of the curve in the plot.  I am also running about a
> positive 5K counts/day.  The 5E-9 figure is still 10X higher than the basic
> 10811 spec, and with 5K counts/day, I have only 160 days left ( I am at
> about 200K counts now, max=1000K).  It always seems the drift is up in EFC
> counts, negative going voltage, and down in frequency.
> 
> 
> 
> An interesting observation, I would notice a periodic dip in the time
> interval error.  I would come home from work, turn on the air conditioning,
> and I after an hour or so, I would see the time interval error take a large
> dip.  I didn't think the drift vs temperature was that sensitive.
> 
> 
> 
> I also wonder if the excessive heat of the double oven shortens the life or
> accelerates the aging of a typical 10811.  The heat certainly dries out the
> polyester tape and silicon rubber foam inside. Could it accelerate the aging
> of the oscillator, shorting the life of the oscillator and the useful life
> of the GPSDO?  It's no wonder the Morions on Ebay are sold by the
> manufacturing date.  Once you run out of EFC, that's all she wrote..  It
> makes me question the wisdom of buying a used 10811 double oven oscillator,
> how much life is left?
> 
> 
> 
> So, does anyone have any comments on the excessive drift of the 10811?
> 
> 
> 
> On another tangent, I tried hooking up a Morion to the Z3805A.  I used an
> inverting amplifier for the EFC since the coefficient is positive and on the
> 10811 is negative.  I never achieved good control before the Morion itself
> died.  I will probably continue working on marrying a new OCXO to the Z380XA
> control board.  I need an alternate source for the OCXO without depending on
> used double oven 10811s.
> 
> 
> 
> 
> 
> Bob
> 
> AC2AZ
> 
> 
> 
> 
> 
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[time-nuts] Z380XA The saga of the aging 10811

[Bob Benward]

Hi All,

I would like to convey the saga of my Z3801A and my Z3805A.

 

I purchased a Z3801A a few years ago at the Dayton Hamfest.  I got it
running and a few months later the unit lost it's GPS lock.  I did some
trouble shooting and finally realized the unit ran out of EFC range.  I
opened the double oven 10811 and retuned the unit to the lower end.  The
unit ran for another year or so, and then the oscillator died.  The
frequency was close, but the amplitude dropped too low for the circuitry to
lock on to.  I put the Z3801A aside and purchased a Z3805A from China (I
think from Yixunhk).

 

I plugged in the Z3805A and it ran for a few years.  One day, a few days
after a relatively active thunderstorm, I notice the alert light was on and
I had lost GPS lock.  I thought a close strike wiped out the GPS receiver.
After a lot of screwing around, I figured out that the 10811 had also lost
EFC range.  The output voltage sat at the neg2.0V level and would not budge.
I opened up the 10811 and readjusted the tuning to put the EFC counts at
below 100K.  I never reassembled the oscillator, I just left it sprawled out
on the table.  Checking the EFC stats, it started with a relatively high
1E-8 per day of drift.  It has since calmed down to 5E-9, and you can see a
slight flattening of the curve in the plot.  I am also running about a
positive 5K counts/day.  The 5E-9 figure is still 10X higher than the basic
10811 spec, and with 5K counts/day, I have only 160 days left ( I am at
about 200K counts now, max=1000K).  It always seems the drift is up in EFC
counts, negative going voltage, and down in frequency.

 

An interesting observation, I would notice a periodic dip in the time
interval error.  I would come home from work, turn on the air conditioning,
and I after an hour or so, I would see the time interval error take a large
dip.  I didn't think the drift vs temperature was that sensitive.

 

I also wonder if the excessive heat of the double oven shortens the life or
accelerates the aging of a typical 10811.  The heat certainly dries out the
polyester tape and silicon rubber foam inside. Could it accelerate the aging
of the oscillator, shorting the life of the oscillator and the useful life
of the GPSDO?  It's no wonder the Morions on Ebay are sold by the
manufacturing date.  Once you run out of EFC, that's all she wrote..  It
makes me question the wisdom of buying a used 10811 double oven oscillator,
how much life is left?

 

So, does anyone have any comments on the excessive drift of the 10811?

 

On another tangent, I tried hooking up a Morion to the Z3805A.  I used an
inverting amplifier for the EFC since the coefficient is positive and on the
10811 is negative.  I never achieved good control before the Morion itself
died.  I will probably continue working on marrying a new OCXO to the Z380XA
control board.  I need an alternate source for the OCXO without depending on
used double oven 10811s.

 

 

Bob

AC2AZ

 

 

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