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

Bob Camp kb8tq at n1k.org
Tue Sep 15 06:58:29 EDT 2015


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 <rbenward at 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-bounces at 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 <rbenward at 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-bounces at febo.com] On Behalf Of
>>>>>>>> ed breya
>>>>>>>> Sent: Tuesday, September 08, 2015 10:55 AM
>>>>>>>> To: time-nuts at 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 at 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 at febo.com To unsubscribe, go to
>>>>> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
>>>>> and follow the instructions there.
>>>>> 
>>>> _______________________________________________
>>>> time-nuts mailing list -- time-nuts at 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: 4419/10639 - Release Date:
>>>> 09/14/15
> 
> _______________________________________________
> time-nuts mailing list -- time-nuts at febo.com
> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.



More information about the time-nuts mailing list