Re: [time-nuts] Temperature sensors and quartz crystals (was: HP5061B Versus HP5071 Cesium Line Frequencies)

[Poul-Henning Kamp]

In message 
, "Dr. David Kirkby (Kirkby Microwave Ltd)" writes:

>I can't find it now, but I know someone said thermocouples are obsolete. I
>spoke to a friend tonight who services industrial boilders. He said
>thermocouples are far from obsolesce, at temperatures of a few hundred deg
>C, as nothing else works.

Thermocouples are not obsolete.

If nothing else because they are cheap and can be made on the spot and
in all sorts of weird shapes.

The only thing which competes with thermocouples in high temperature
is platinum, which is horribly expensive by comparison and more
prone to noise than thermocouples.

-- 
Poul-Henning Kamp   | UNIX since Zilog Zeus 3.20
p...@freebsd.org | TCP/IP since RFC 956
FreeBSD committer   | BSD since 4.3-tahoe
Never attribute to malice what can adequately be explained by incompetence.
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[time-nuts] Lucent RFTG-u REF-0 Standalone Operation (Dan Watson work)

[Gregory Beat]

Starting in August 2015, Dan Watson (Sync Channel Blog) started a project to 
develop a GPS board to "plug into" the Lucent KS-24361, RTFG-u REF-0 for 
standalone operation (without the REF-1 module)
http://syncchannel.blogspot.com/2015/08/standalone-operation-of-lucent-ks-24361.html

By October, he had a GPS board (Tria) that converted uBlox timing receiver 
output to the format desired by Lucent box (Motorola Oncore UT).
http://syncchannel.blogspot.com/2015/10/tria-gps-success-in-ref-0.html
His last post in November 2015 was about dongles.
http://syncchannel.blogspot.com/2015/11/denuo-gps-hits-rev-b-dongles.html

In 2016 he posted his later work on OSHPark, but stopped Blog posting about a 
year ago.
Anyone have an update?  He has commented in past that he is easily distracted. 

greg, w9gb

Sent from iPad Air
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Re: [time-nuts] Poor man's oven

[David]

I have never been able to find a reference to them on the internet but
there was a similar product intended for TO-99 packages that could be
used with operational amplifiers.

On Mon, 5 Jun 2017 08:35:35 + (UTC), you wrote:

>  The Crystal heater clip wasa Murata "Posistor" soldered onto a clipand they 
>were marketed by Murata.
>I once purchased a small amount of theseand used them as "poor man's ovens".
>Although not perfect by far, they did theirjob and kept my UHF gear stable.
>Murata dropped that product many yearsago and I have not been able to findany 
>similar product. The Posistors arelisted by eg. Digi-key but they do not stock 
>them.
>Ulf - SM6GXV
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Re: [time-nuts] Free to a good home: HP 100E Freq. Standard

[paul swed]

Ellen its free.
Regards
Paul
WB8TSL

On Mon, Jun 5, 2017 at 7:38 PM, Ellen Franke  wrote:

> I am interested, very interested. How much? Do you accept PayPal?
>
> John Franke
> 4500 Ibis Ct
> Portsmouth, VA 23703
>
> > On June 5, 2017 at 2:48 PM Neal MacDonald  wrote:
> >
> >
> > I have an HP 100E Frequency Standard that I found at a garage sale and
> bought on a whim a while ago. I don’t have much use for it, but it seems
> like a shame to toss it so I figured I’d offer it up here. It’s yours for
> free, just pay shipping costs from the DC area. I was told by the original
> owner that the vertical deflection doesn’t work, but I didn’t have the
> technical knowhow to attempt to diagnose the issue. I also have a scanned
> copy of the original manual I can pass along.
> >
> > Some info here: http://hpmemoryproject.org/news/100e/hp100e_page_00.htm
> 
> > Pictures here: https://imgur.com/a/JL8h4 
> >
> > Thanks,
> > Neal
> > ___
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> mailman/listinfo/time-nuts
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Re: [time-nuts] MIT flea meet-up for time-nuts

[paul swed]

Eric it was good to meet you and your wife at MIT. My wife and I were
digging through Berry's parts. It was a pretty nice MIT. Though as they say
the pick-ns are getting thinner.
Regards
Paul
WB8TSL

On Fri, May 19, 2017 at 1:31 PM, Eric Scace  wrote:

> The MIT Flea  occurs this Sunday (May
> 21) from 09:00–14:00.
>
> Come join us for a bite at Flour Café  locations/central-square/> at the end of the block (190 Mass Ave) at
> 11:30. I’d love to hear about your time projects & lab, see your trophies
> from the flea market, etc.
>
> Drop me a note off-list if you can come — I’ll save you a seat at the
> table. If the weather is good, we’ll be outside.
>
> — Eric K3NA
>
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Re: [time-nuts] Free to a good home: HP 100E Freq. Standard

[Ellen Franke]

I am interested, very interested. How much? Do you accept PayPal?

John Franke
4500 Ibis Ct
Portsmouth, VA 23703

> On June 5, 2017 at 2:48 PM Neal MacDonald  wrote:
>
>
> I have an HP 100E Frequency Standard that I found at a garage sale and bought 
> on a whim a while ago. I don’t have much use for it, but it seems like a 
> shame to toss it so I figured I’d offer it up here. It’s yours for free, just 
> pay shipping costs from the DC area. I was told by the original owner that 
> the vertical deflection doesn’t work, but I didn’t have the technical knowhow 
> to attempt to diagnose the issue. I also have a scanned copy of the original 
> manual I can pass along.
>
> Some info here: http://hpmemoryproject.org/news/100e/hp100e_page_00.htm 
> 
> Pictures here: https://imgur.com/a/JL8h4 
>
> Thanks,
> Neal
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Re: [time-nuts] Temperature sensors and quartz crystals (was: HP5061B Versus HP5071 Cesium Line Frequencies)

[Dr. David Kirkby (Kirkby Microwave Ltd)]

On 5 June 2017 at 00:59, Attila Kinali  wrote:

> Moin,
>
> This discussion is kind of getting heated.
> Let's put some facts in, to steer it away from
> opinion based discussion.
>

I can't find it now, but I know someone said thermocouples are obsolete. I
spoke to a friend tonight who services industrial boilders. He said
thermocouples are far from obsolesce, at temperatures of a few hundred deg
C, as nothing else works.


Dave
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Re: [time-nuts] Poor man's oven

[Charles Steinmetz]

Chris wrote:


Today all you need is a reliable way to measure the error
between the crystals' current temperature and the set  point.


That's all that's ever been needed.  But it is devilishly difficult to 
measure the actual quartz temperature, or even to find a good proxy that 
is easier to measure.


There is a fair body of published research on these topics, including 
Rick's (et al.) work on zero-gradient ovens.


Keep this in mind when someone says they are controlling the "oven 
temperature" to 0.001C (or even 0.1C).  They are measuring *something*, 
and may even be holding whatever it is "constant" within fairly tight 
tolerances.  But they have no idea what the quartz temperature is, and 
no way to know with precision the relationship between the measured 
temperature and the actual quartz temperature.


Some years ago, I consulted for a research group that was using a number 
of non-contact technologies to measure the temperature of oscillating 
quartz crystals.  The results were promising, but there were some issues 
with measuring the temperature (which is, essentially, quantifying tiny 
random molecular motions within the crystal lattice) against the 
background of the hugely greater macro motion of the vibating quartz.  I 
never knew the final conclusions, nor am I aware of any systems designed 
using these principles or methods.  But it is something to think about 
if you *really* want a temperature-stable oscillator.


Best regards,

Charles


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Re: [time-nuts] Free to a good home: HP 100E Freq. Standard

[Jeremy Nichols]

I'd love to have one but yes, shipping from D.C. to CA would be at least
$100 and more if you wanted it to arrive in one piece. This one should go
to an enthusiast in the mid-east (is that the correct term for the middle
Atlantic states?). 

Jeremy
N6WFO


On Mon, Jun 5, 2017 at 4:58 PM Bob kb8tq  wrote:

> Hi
>
> If there are no takers from the rest of the list, I’ll drive down and pick
> it up. Shipping a beast like this
> is a royal pain. Let’s wait a couple weeks and see if anybody else wants
> it.
>
> Bob
>
> > On Jun 5, 2017, at 2:48 PM, Neal MacDonald  wrote:
> >
> > I have an HP 100E Frequency Standard that I found at a garage sale and
> bought on a whim a while ago. I don’t have much use for it, but it seems
> like a shame to toss it so I figured I’d offer it up here. It’s yours for
> free, just pay shipping costs from the DC area. I was told by the original
> owner that the vertical deflection doesn’t work, but I didn’t have the
> technical knowhow to attempt to diagnose the issue. I also have a scanned
> copy of the original manual I can pass along.
> >
> > Some info here: http://hpmemoryproject.org/news/100e/hp100e_page_00.htm
> 
> > Pictures here: https://imgur.com/a/JL8h4 
> >
> > Thanks,
> > Neal
> > ___
> > 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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-- 
Sent from Gmail Mobile
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Re: [time-nuts] Poor man's oven

[Bob kb8tq]

Hi

That paper is the basis for the MCXO. It is an interesting way to do a TCXO. 
The drift between the two modes makes it a difficult thing to master in an OCXO.
Plating a pair of electrodes (one pair per mode) is also an approach that has 
been
tried. 

Bob

> On Jun 5, 2017, at 7:20 PM, Chris Caudle  wrote:
> 
> On Mon, June 5, 2017 5:38 pm, Charles Steinmetz wrote:
>> Some years ago, I consulted for a research group that was using a number
>> of non-contact technologies to measure the temperature of oscillating
>> quartz crystals.
> 
> In most cases what you really care about is the stability of the
> frequency, and the temperature of the crystal is just a proxy for that,
> correct?
> I thought there was some effect where different modes of oscillation
> shifted by different amounts with temperature, and if you had two
> oscillation circuits running from the same crystal but different modes,
> you could use the shift in difference frequency between the two modes to
> infer the temperature change.
> 
> Found a reference in the Vig tutorial:
> S. Schodowski, "Resonator Self-Temperature-Sensing Using a
> Dual-Harmonic-Mode Crystal Oscillator," Proc. 43rd Annual Symposium on
> Frequency Control, pp. 2-7, 1989, IEEE Catalog No. 89CH2690-6.
> 
> From page 48 of Vig tutorial version 8.5.5.3 May 2013:
> As is shown in chapter 4, see “Effects of Harmonics on f vs. T,” the f
> vs. T of the fundamental mode of a resonator is different from that of
> the third and higher overtones.  This fact is exploited for
> “self-temperature sensing” in the microcomputer compensated crystal
> oscillator (MCXO). The fundamental (f1) and third overtone (f3)
> frequencies are excited simultaneously (“dual mode” excitation) and a
> beat frequency fb is generated such that fb = 3f1 - f3 (or fb = f1 -
> f3/3). The fb is a monotonic and nearly linear function of
> temperature, as is shown above for a 10 MHz 3rd overtone (3.3. MHz
> fundamental mode) SC-cut resonator.
> 
> The graph shows a line with slope of around 80ppm/deg C.  Not sure what
> that translates to in terms of what you could realistically measure and
> use for frequency compensation.  I guess you could use that information to
> either control an oven or just let the crystal run free and control a
> synthesizer for the used output.
> 
> -- 
> Chris Caudle
> 
> 
> 
> 
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Re: [time-nuts] Poor man's oven

[Bob kb8tq]

Hi

For further info on just why the crystal temperature is such a crazy thing to 
track, check out
Rick’s paper. At first glance it *seems* like it’s a trivial thing. In reality, 
gradients are a very
big deal.

Bob

> On Jun 5, 2017, at 6:38 PM, Charles Steinmetz  wrote:
> 
> Chris wrote:
> 
>> Today all you need is a reliable way to measure the error
>> between the crystals' current temperature and the set  point.
> 
> That's all that's ever been needed.  But it is devilishly difficult to 
> measure the actual quartz temperature, or even to find a good proxy that is 
> easier to measure.
> 
> There is a fair body of published research on these topics, including Rick's 
> (et al.) work on zero-gradient ovens.
> 
> Keep this in mind when someone says they are controlling the "oven 
> temperature" to 0.001C (or even 0.1C).  They are measuring *something*, and 
> may even be holding whatever it is "constant" within fairly tight tolerances. 
>  But they have no idea what the quartz temperature is, and no way to know 
> with precision the relationship between the measured temperature and the 
> actual quartz temperature.
> 
> Some years ago, I consulted for a research group that was using a number of 
> non-contact technologies to measure the temperature of oscillating quartz 
> crystals.  The results were promising, but there were some issues with 
> measuring the temperature (which is, essentially, quantifying tiny random 
> molecular motions within the crystal lattice) against the background of the 
> hugely greater macro motion of the vibating quartz.  I never knew the final 
> conclusions, nor am I aware of any systems designed using these principles or 
> methods.  But it is something to think about if you *really* want a 
> temperature-stable oscillator.
> 
> Best regards,
> 
> Charles
> 
> 
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Re: [time-nuts] Free to a good home: HP 100E Freq. Standard

[Bob kb8tq]

Hi

If there are no takers from the rest of the list, I’ll drive down and pick it 
up. Shipping a beast like this
is a royal pain. Let’s wait a couple weeks and see if anybody else wants it.

Bob

> On Jun 5, 2017, at 2:48 PM, Neal MacDonald  wrote:
> 
> I have an HP 100E Frequency Standard that I found at a garage sale and bought 
> on a whim a while ago. I don’t have much use for it, but it seems like a 
> shame to toss it so I figured I’d offer it up here. It’s yours for free, just 
> pay shipping costs from the DC area. I was told by the original owner that 
> the vertical deflection doesn’t work, but I didn’t have the technical knowhow 
> to attempt to diagnose the issue. I also have a scanned copy of the original 
> manual I can pass along.
> 
> Some info here: http://hpmemoryproject.org/news/100e/hp100e_page_00.htm 
> 
> Pictures here: https://imgur.com/a/JL8h4 
> 
> Thanks,
> Neal
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Re: [time-nuts] Poor man's oven

[Chris Caudle]

On Mon, June 5, 2017 5:38 pm, Charles Steinmetz wrote:
> Some years ago, I consulted for a research group that was using a number
> of non-contact technologies to measure the temperature of oscillating
> quartz crystals.

In most cases what you really care about is the stability of the
frequency, and the temperature of the crystal is just a proxy for that,
correct?
I thought there was some effect where different modes of oscillation
shifted by different amounts with temperature, and if you had two
oscillation circuits running from the same crystal but different modes,
you could use the shift in difference frequency between the two modes to
infer the temperature change.

Found a reference in the Vig tutorial:
S. Schodowski, "Resonator Self-Temperature-Sensing Using a
Dual-Harmonic-Mode Crystal Oscillator," Proc. 43rd Annual Symposium on
Frequency Control, pp. 2-7, 1989, IEEE Catalog No. 89CH2690-6.

>From page 48 of Vig tutorial version 8.5.5.3 May 2013:
As is shown in chapter 4, see “Effects of Harmonics on f vs. T,” the f
vs. T of the fundamental mode of a resonator is different from that of
the third and higher overtones.  This fact is exploited for
“self-temperature sensing” in the microcomputer compensated crystal
oscillator (MCXO). The fundamental (f1) and third overtone (f3)
frequencies are excited simultaneously (“dual mode” excitation) and a
beat frequency fb is generated such that fb = 3f1 - f3 (or fb = f1 -
f3/3). The fb is a monotonic and nearly linear function of
temperature, as is shown above for a 10 MHz 3rd overtone (3.3. MHz
fundamental mode) SC-cut resonator.

The graph shows a line with slope of around 80ppm/deg C.  Not sure what
that translates to in terms of what you could realistically measure and
use for frequency compensation.  I guess you could use that information to
either control an oven or just let the crystal run free and control a
synthesizer for the used output.

-- 
Chris Caudle




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Re: [time-nuts] Poor man's oven

[Chris Albertson]

On Mon, Jun 5, 2017 at 3:38 PM, Charles Steinmetz 
wrote:

> Chris wrote:
>
> Today all you need is a reliable way to measure the error
>> between the crystals' current temperature and the set  point.
>>
>
> That's all that's ever been needed.  But it is devilishly difficult to
> measure the actual quartz temperature, or even to find a good proxy that is
> easier to measure.
>
> There is a fair body of published research on these topics, including
> Rick's (et al.) work on zero-gradient ovens.
>
> Keep this in mind when someone says they are controlling the "oven
> temperature" to 0.001C (or even 0.1C).  They are measuring *something*, and
> may even be holding whatever it is "constant" within fairly tight
> tolerances.  But they have no idea what the quartz temperature is, and no
> way to know with precision the relationship between the measured
> temperature and the actual quartz temperature.
>

How much does this matter?  What we measure is the ambient temperature
inside the insulated box that contains the crystal.   The assumption is
that given some time the temperature will be uniform. OK, so the assumption
is not 100% correct but lets say the crystal is held to a range of 0.1C
 This is a reasonable goal for a home shop made controller.

Here is another question:
Lets assume we place the operating point on the flat part of the curve with
say a 1.0 C absolute error and can hold the relative temperature to 0.1C
 What does this mean in terms of frequency.?

This is a "Poor Man's" oven.   So really the question is this:  I have a
$10 budget, shouldI blow half my budget on a better sensor or is the 75
cent part good enough.  Or is it worth buying a second 75 cent sensor so I
can detect a temperature gradient  With a poor man's budget, I think the
trick is to use a good size thermal mass, chunks of scrap meter are cheap.




>
> Some years ago, I consulted for a research group that was using a number
> of non-contact technologies to measure the temperature of oscillating
> quartz crystals.  The results were promising, but there were some issues
> with measuring the temperature (which is, essentially, quantifying tiny
> random molecular motions within the crystal lattice) against the background
> of the hugely greater macro motion of the vibating quartz.  I never knew
> the final conclusions, nor am I aware of any systems designed using these
> principles or methods.  But it is something to think about if you *really*
> want a temperature-stable oscillator.
>
> Best regards,
>
> Charles
>
>
>
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> ailman/listinfo/time-nuts
> and follow the instructions there.
>



-- 

Chris Albertson
Redondo Beach, California
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[time-nuts] PPS sync

[Mark Sims]

Yes, that is the sawtooth correction parameter.  If a receiver reports the 
sawtooth correction value, but not a GPSDO EFC dac setting,  Heather plots the 
sawtooth value as the GD plot and shows it where the DAC value is normally 
shown.

Sawtooth values are seldom simple ramps.   They represent the difference 
between the GPS PPS signal and (usually) the GPS CPU clock.   They have all 
sorts of interesting structure to them (like the infamous "hanging bridges") 
The magnitude of the sawtooth range depends upon the GPS CPU.  Older devices 
may have a +/- 30 ns range and newer ones like the Venus timing receivers are 
in the +/- 6 ns range.

A GPSDO usually derives its PPS output by dividing the 10 MHz OCXO output down. 
  The GPSDO control loop removes the sawtooth error.   A good GPSDO takes 
advantage of the sawtooth correction message from the receiver to minimize the 
effects of the sawtooth error on  the control loop.   The Thunderbolt locks the 
GPS receiver clocks to the 10 MHz OCXO and does not have any sawtooth error to 
compensate for.

---

> Mark Sims, can you comment on the SawT parameter, I assumed being reported by 
> the M12 GPS, displayed on Lady Heather?
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Re: [time-nuts] Temperature sensors and quartz crystals (was: HP5061B Versus HP5071 Cesium Line Frequencies)

[Bruce Griffiths]

Additional info/papers on Thermistor stability:

http://www.digikey.com/en/pdf/u/us-sensor/us-sensor-stability-long-term-aging

https://www.thermistor.com/sites/default/files/specsheets/T150-Series-Stability.pdf

https://www.vishay.com/docs/49498/ntcs-e3-smt_vmn-pt0283.pdf

>From LIGO:

http://www.aspe.net/publications/Annual_2008/POSTERS/08UNCER/2643.PDF

Bruce


> 
> On 06 June 2017 at 09:49 Bruce Griffiths  
> wrote:
> 
> Here's a NIST paper on Thermistor stability:
> 
> http://nvlpubs.nist.gov/nistpubs/jres/83/jresv83n3p247_A1b.pdf
> 
> Bruce
> 
> > > 
> > On 06 June 2017 at 01:45 Bob kb8tq  wrote:
> > 
> > Hi
> > 
> > Well, as part of the process of designing them into OCXO’s you do 
> > indeed check their long term stability.
> > The test is done in an indirect fashion so you only come up with a 
> > “it’s below the limit” sort of number. The
> > typical process involves running a group of OCXO’s on turn to check 
> > the frequency and then shifting them
> > off turn to make a sort of thermometer. After a few months of 
> > frequency readings you take them back to turn
> > for a while. Relative frequency shift math gives you a stability 
> > number for the thermistor and the rest of the
> > circuitry. You may repeat the run for months / shift process a 
> > couple of times. If the answer isn’t “I can’t see
> > a difference” you look for a new thermistor. Since it’s a long 
> > drawn out test, the tendency is to stick with a
> > vendor’s part for quite a while. The parts also tend to be design 
> > specific so what works in my (say SMT)
> > design may not work well in your (say chip and wire) design.
> > 
> > Bob
> > 
> > > > > 
> > > > > > > 
> > > > On Jun 5, 2017, at 9:20 AM, romeo987 
> > > >  wrote:
> > > > 
> > > > > > > 
> > > Hi, guys
> > > I have been following time nuts and volt nuts for some time 
> > > out of interest and fascination. Although my personal backyard hobby is 
> > > more along a volt nuts line, the two worlds often collide - like in this 
> > > discussion of temperature sensors, and in particular their long term 
> > > stability. NTC thermistors appear to be very commonly used in ovens used 
> > > to stabilize voltage references (solid state as well as chemical) . I 
> > > have long wondered about their stability. If, as Bruce asserts, "high 
> > > quality thermistors can achieve drifts of around 1mK/month" then it 
> > > appears that this level of drift is a significant factor in the 
> > > "apparent" aging of, say, a bank of Weston cells (which is still my best 
> > > backyard shot at a voltage reference).
> > > 
> > > I have had no luck with Google; Bruce's statement is the 
> > > first quantified allusion that I have seen to this subject. Is there any 
> > > actual data available on the long term performance of NTC sensors?
> > > 
> > > Roman
> > > 
> > > > > > > 
> > > > > > > > > 
> > > > > > > > > > > 
> > > > > > On 5 Jun 2017, at 9:53 AM, Bruce Griffiths 
> > > > > >  wrote:
> > > > > > 
> > > > > > > > > > > 
> > > > > > > > > 
> > > > The other issue that needs to be considered is the 
> > > > drift in temperature sensor characteristics when operated at a constant 
> > > > temperature (as is typical in a continuously operated crystal oven). 
> > > > High quality thermistors can achieve drifts of around 1mK/month. Its 
> > > > unlikely that something as complex as an AD590 will achieve a similar 
> > > > drift (1nA/month in a operating current of 300uA or so at 25C). High 
> > > > quality PRT sensors drift even less than thermistors when operating at 
> > > > constant temperature.
> > > > 
> > > > Bruce
> > > > 
> > > > > > > > > 
> > > > > > > > > > > 
> > > > > > > > > > > > > 
> > > > > > > > > > > > > > > 
> > > > > > > > .On 05 June 2017 at 11:59 
> > > > > > > > Attila Kinali  wrote:
> > > > > > > > 
> > > > > > > > > > > > > > > 
> > > > > > > > > > > > > 
> > > > > > > > > > > 
> > > > > Moin,
> > > > > 
> > > > > This discussion is kind of getting heated.
> > > > > Let's put some facts in, to steer it away from
> > > > > opinion based discussion.
> > > > > 
> > > > > On Sun, 4 Jun 2017 08:44:33 -0700
> > > > > "Donald E. Pauly"  wrote:
> > > > > 
> > > > > > > > > > > 
> > > > > > > > > > > > > 
> > > > > > >   

Re: [time-nuts] Temperature sensors and quartz crystals (was: HP5061B Versus HP5071 Cesium Line Frequencies)

[Bruce Griffiths]

Here's a NIST paper on Thermistor stability:

http://nvlpubs.nist.gov/nistpubs/jres/83/jresv83n3p247_A1b.pdf

Bruce

> 
> On 06 June 2017 at 01:45 Bob kb8tq  wrote:
> 
> Hi
> 
> Well, as part of the process of designing them into OCXO’s you do indeed 
> check their long term stability.
> The test is done in an indirect fashion so you only come up with a “it’s 
> below the limit” sort of number. The
> typical process involves running a group of OCXO’s on turn to check the 
> frequency and then shifting them
> off turn to make a sort of thermometer. After a few months of frequency 
> readings you take them back to turn
> for a while. Relative frequency shift math gives you a stability number 
> for the thermistor and the rest of the
> circuitry. You may repeat the run for months / shift process a couple of 
> times. If the answer isn’t “I can’t see
> a difference” you look for a new thermistor. Since it’s a long drawn out 
> test, the tendency is to stick with a
> vendor’s part for quite a while. The parts also tend to be design 
> specific so what works in my (say SMT)
> design may not work well in your (say chip and wire) design.
> 
> Bob
> 
> > > 
> > On Jun 5, 2017, at 9:20 AM, romeo987  
> > wrote:
> > 
> > Hi, guys
> > I have been following time nuts and volt nuts for some time out of 
> > interest and fascination. Although my personal backyard hobby is more along 
> > a volt nuts line, the two worlds often collide - like in this discussion of 
> > temperature sensors, and in particular their long term stability. NTC 
> > thermistors appear to be very commonly used in ovens used to stabilize 
> > voltage references (solid state as well as chemical) . I have long wondered 
> > about their stability. If, as Bruce asserts, "high quality thermistors can 
> > achieve drifts of around 1mK/month" then it appears that this level of 
> > drift is a significant factor in the "apparent" aging of, say, a bank of 
> > Weston cells (which is still my best backyard shot at a voltage reference).
> > 
> > I have had no luck with Google; Bruce's statement is the first 
> > quantified allusion that I have seen to this subject. Is there any actual 
> > data available on the long term performance of NTC sensors?
> > 
> > Roman
> > 
> > > > > 
> > > On 5 Jun 2017, at 9:53 AM, Bruce Griffiths 
> > >  wrote:
> > > 
> > > The other issue that needs to be considered is the drift in 
> > > temperature sensor characteristics when operated at a constant 
> > > temperature (as is typical in a continuously operated crystal oven). High 
> > > quality thermistors can achieve drifts of around 1mK/month. Its unlikely 
> > > that something as complex as an AD590 will achieve a similar drift 
> > > (1nA/month in a operating current of 300uA or so at 25C). High quality 
> > > PRT sensors drift even less than thermistors when operating at constant 
> > > temperature.
> > > 
> > > Bruce
> > > 
> > > > > > > 
> > > > .On 05 June 2017 at 11:59 Attila Kinali 
> > > >  wrote:
> > > > 
> > > > Moin,
> > > > 
> > > > This discussion is kind of getting heated.
> > > > Let's put some facts in, to steer it away from
> > > > opinion based discussion.
> > > > 
> > > > On Sun, 4 Jun 2017 08:44:33 -0700
> > > > "Donald E. Pauly"  wrote:
> > > > 
> > > > > > > > > 
> > > > > I stand by my remark that thermistors have been 
> > > > > obsolete for over 40
> > > > > years. The only exception that I know of is 
> > > > > cesium beam tubes that
> > > > > must withstand a 350° C bakeout. Thermistors are 
> > > > > unstable and
> > > > > manufactured with a witches brew straight out of 
> > > > > MacBeth. Their
> > > > > output voltages are tiny and are they 
> > > > > inconvenient to use at different
> > > > > temperatures.
> > > > > 
> > > > > If you really mean thermistors, and not, as Bob 
> > > > > suggested thermocouples,
> > > > > then I have to disagree. The most stable 
> > > > > temperature sensors are
> > > > > platinum wire sensors. The standards class PRT's 
> > > > > are the gold standard
> > > > > when it comes to temperature measurement, for a 
> > > > > quite wide range
> > > > > (-260°C to +960°C) and are considered very 
> > > > > stable. They offer (absolute)
> > > > > accuracies in the order of 10mK in the 
> > > > > temperature range below 400°C.
> > > > > Even industrial grade PRT sensors give you an 
> > > > > absolute accuracy better
> > > > > than 0.1K up to 200-300°C. The "c

[time-nuts] Free to a good home: HP 100E Freq. Standard

[Neal MacDonald]

I have an HP 100E Frequency Standard that I found at a garage sale and bought 
on a whim a while ago. I don’t have much use for it, but it seems like a shame 
to toss it so I figured I’d offer it up here. It’s yours for free, just pay 
shipping costs from the DC area. I was told by the original owner that the 
vertical deflection doesn’t work, but I didn’t have the technical knowhow to 
attempt to diagnose the issue. I also have a scanned copy of the original 
manual I can pass along.

Some info here: http://hpmemoryproject.org/news/100e/hp100e_page_00.htm 

Pictures here: https://imgur.com/a/JL8h4 

Thanks,
Neal
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Re: [time-nuts] PPS sync

[Jerry Hancock]

Chris, I think you are onto something.  Running Lady Heather on this unit I see 
a line under “receiver” with the term “SawT” and a parameter of 24ns.  So if we 
combine this information with what you teach below, it’s starting to look like 
maybe the M12 unit is doing something different than the Lucent.  I am watching 
it today and I see 5 PPS that vary from the lucent pulse (used as a trigger) 
each about +20ns until it resets. 

Mark Sims, can you comment on the SawT parameter, I assumed being reported by 
the M12 GPS, displayed on Lady Heather?

Thanks 


> On Jun 5, 2017, at 10:15 AM, Chris Albertson  
> wrote:
> 
> I did not finish the sawtooth explanation.  One of the units is designed
> such that the PPS is always on the raising edge of an internal 10MHz clock.
>   If the 10MHz clock were perfect this means the maximum error is 1/2
> cycle.   The software in the GPS choose site best edge to minimize error.
> the jump you see it when it selects a different cycle and jumpsThe
> software tracks the error and outputs an estimate of the root on the serial
> channel.
> 
> You can verify this by plotting the sawtooth correction vs.time and see
> that it lines up with your observation of the jump back to zero error.
> 
> There might still be errors cause by other things, like improper self
> survey but the results you reported are exactly like what one would expect
> from a unit that uses an oscillator edge to trigger PPS.  It other words
> what you see is a design feature not an error.
> 
> On Mon, Jun 5, 2017 at 6:40 AM, Jerry Hancock  wrote:
> 
>> It was off 7.5KM, that’s a little beyond groggy, no?  More like a trip to
>> Vegas.
>> 
>> I’ll let it rerun the survey and see if it gets closer.
>> 
>>> On Jun 4, 2017, at 9:50 PM, Mark Sims  wrote:
>>> 
>>> Be careful when using one unit's location to set a different model's
>> location...  particularly the altitude.   Some devices report altitude in
>> MSL, others in AGL... and different units may use different models for the
>> ellipsoid.   You are always better off using coordinates generated by the
>> particular device (either the built-in self survey or something like Lady
>> Heather's precision survey).
>>> 
>>> I did some tests while developing Lady Heather's precision survey code.
>> I got pretty consistent lat/lon/alt results on the same units but
>> consistent offsets between different models of receivers.
>>> 
>>> I would suggest letting the Motorola re-surevy itself...  it may have
>> been a bit groggy after first being powered up after a few years of
>> sleep... I know I am...
>>> 
>>> ---
>>> 
 I then set the M12 reference location to the Lucent location as I know
>> it to be correct.
>>> ___
>>> 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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>> and follow the instructions there.
>> 
> 
> 
> 
> -- 
> 
> Chris Albertson
> Redondo Beach, California
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Re: [time-nuts] Temperature sensors and quartz crystals (was: HP5061B Versus HP5071 Cesium Line Frequencies)

[Poul-Henning Kamp]

In message <20170605133013.526e8505158e68b6a8091...@kinali.ch>, Attila Kinali w
rites:

>> Where do digital sensors (e.g. ds1820 and some more recent parts from TI)
>> fit into this ?
>
>AFAIK, these are all band-gap temperature sensors. 

The Ds1820 is based on the frequency difference between two
free-running silicon oscillators with different physical design.


-- 
Poul-Henning Kamp   | UNIX since Zilog Zeus 3.20
p...@freebsd.org | TCP/IP since RFC 956
FreeBSD committer   | BSD since 4.3-tahoe
Never attribute to malice what can adequately be explained by incompetence.
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Re: [time-nuts] Poor man's oven

[Chris Albertson]

Look at the dates on the uses of these exotic temperature controllers.
Organic compounds and positive temp coefficients and so on.  All these were
used before the current era.  Today all you need is a reliable way to
measure the error between the crystals' current temperature and the set
point.

Those exotic methods were good back when controllers were analog devices
build with op-amps and precision resisters and every math operation cost
you one more op-amp.   Today we can do a million floating point operations
per second for the cost of one kind good op-amp.

The trick with using a uP and it's built-in A/D converters is scale.  You
want the limited 10-bits of revolution to fall over the operating range
which is very narrow, like 1C.   Anything outside of that is either  or
 and only seen at start-up.,  So at start up the the controller is on
"bang-bang" mode then later you have milli-degree resolution over your 1C
range.   Basically you are measuring noise. but your $2 uP can take 100,000
measurments per second and putt tour a digital filter.

Today we can do things the old-time designers even as recent as the 1980's
would not even dream of doing and it cost under $10.

On Mon, Jun 5, 2017 at 1:35 AM, Ulf Kylenfall via time-nuts <
time-nuts@febo.com> wrote:

>   The Crystal heater clip wasa Murata "Posistor" soldered onto a clipand
> they were marketed by Murata.
> I once purchased a small amount of theseand used them as "poor man's
> ovens".
> Although not perfect by far, they did theirjob and kept my UHF gear stable.
> Murata dropped that product many yearsago and I have not been able to
> findany similar product. The Posistors arelisted by eg. Digi-key but they
> do not stock them.
> Ulf - SM6GXV
>
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>



-- 

Chris Albertson
Redondo Beach, California
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Re: [time-nuts] PPS sync

[Chris Albertson]

I did not finish the sawtooth explanation.  One of the units is designed
such that the PPS is always on the raising edge of an internal 10MHz clock.
   If the 10MHz clock were perfect this means the maximum error is 1/2
cycle.   The software in the GPS choose site best edge to minimize error.
 the jump you see it when it selects a different cycle and jumpsThe
software tracks the error and outputs an estimate of the root on the serial
channel.

You can verify this by plotting the sawtooth correction vs.time and see
that it lines up with your observation of the jump back to zero error.

There might still be errors cause by other things, like improper self
survey but the results you reported are exactly like what one would expect
from a unit that uses an oscillator edge to trigger PPS.  It other words
what you see is a design feature not an error.

On Mon, Jun 5, 2017 at 6:40 AM, Jerry Hancock  wrote:

> It was off 7.5KM, that’s a little beyond groggy, no?  More like a trip to
> Vegas.
>
> I’ll let it rerun the survey and see if it gets closer.
>
> > On Jun 4, 2017, at 9:50 PM, Mark Sims  wrote:
> >
> > Be careful when using one unit's location to set a different model's
> location...  particularly the altitude.   Some devices report altitude in
> MSL, others in AGL... and different units may use different models for the
> ellipsoid.   You are always better off using coordinates generated by the
> particular device (either the built-in self survey or something like Lady
> Heather's precision survey).
> >
> > I did some tests while developing Lady Heather's precision survey code.
>  I got pretty consistent lat/lon/alt results on the same units but
> consistent offsets between different models of receivers.
> >
> > I would suggest letting the Motorola re-surevy itself...  it may have
> been a bit groggy after first being powered up after a few years of
> sleep... I know I am...
> >
> > ---
> >
> >> I then set the M12 reference location to the Lucent location as I know
> it to be correct.
> > ___
> > 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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> and follow the instructions there.
>



-- 

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Redondo Beach, California
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Re: [time-nuts] poor-man's oven

[Chris Albertson]

Yes,  Agree.  I wrote tin the first post that "for your use a resistive
heater would be better"

But everything else, I'd do over.  Drill the aluminum block and use thermal
epoxy to hold the sensor in place.   Use a vacuum insulated mug or bowl for
a cover and let a micro controller run a PID loop to control temperature..
  You can keep it within 0.1C without the need to be a control theory
expert. Another order of magnitude would really hard and expensive

The last temperature controller I made was not as good but keeps a rubidium
oscillator within about a degree.   I put a thruster in the Rb's heat sink
and a micro controller adjusts the fan speed.  The self heat from the Rb
unit is enough. The Rb is about the size and shape of an old 3.5 inch
disk drive so I put it n an old disk drive enclosure that already had a
place for a fan.As crude as this is, it is much better then what I had
which was not control.  The Rb output is better then I have means to
measure now.

So same with the poor man's oven.   It can be very good with very little
effort.What has happened is that now we have nearly free micro
controllers and can use daily sophisticated control algorithms that HP
could not use back in the day. We can actually model non linearities in
the sensor.   We can use a full on PID solution rather then the simple
on/off thermostat.

But no you don't want to cool a crystal, I was not suggesting that.   We
happened to have a high gain amplifier that was in effect counting
electrons.

On Mon, Jun 5, 2017 at 2:15 AM, Attila Kinali  wrote:

> On Sun, 4 Jun 2017 22:01:45 -0700
> Chris Albertson  wrote:
>
> > Voltage is proportional to the product of resistance and absolute
> > temperature.   As an experiment place a voltage across a high value
> > resister like say one 1M  raise the volts until you are near the limit of
> > the resister and connect it via a coupler cadaster to an audio amplifier.
> > You will hear white noise in the speakers.
>
> Yes, Johnson noise increases by about 20% (or about 0.8dB)
> when going from 25°C to 90°C. But Johnson noise is usually
> not the first limiting noise one runs into when designing
> a crystal oscillator. I would rather use a simpler,
> "high temperature" oven and invest the time saved into a
> desgining better oscillator structure.
>
>
> > There is a similar effect in semi conductors.  The best example of this
> is
> > visual noise in digital camera, when you tern the gain way up (set the
> ISO
> > high) you can see it in the photo.
> >
> > All of this is proportion; to absolute.
> >
> > As I remember we ran the "oven" at -20C There was a valve used to flash
> out
> > the air inside with inert welding gas to reduce ice.
>
> If the -20°C was used on the camera, then this is not to reduce Johnson
> noise, but the dark current noise. While the former is due to thermal
> vibration of the atom lattice, the later is due to spontaneous forming
> of electron-hole pairs in the p-n junction region. Thus also their
> temperature characteristics differ: While Johnson noise is linear
> in temperature, dark current noise is (almost) exponential in temperature.
> Going down from room temperature to 0°C is something like a factor 100
> (IIRC, from memory, could be wrong) in noise for a CCD. While for
> a resistor, the difference is almost negligible.
>
> Attila Kinali
> --
> You know, the very powerful and the very stupid have one thing in common.
> They don't alters their views to fit the facts, they alter the facts to
> fit the views, which can be uncomfortable if you happen to be one of the
> facts that needs altering.  -- The Doctor
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>



-- 

Chris Albertson
Redondo Beach, California
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Re: [time-nuts] Temperature sensors and quartz crystals (was: HP5061B Versus HP5071 Cesium Line Frequencies)

[Bob kb8tq]

Hi

Well, as part of the process of designing them into OCXO’s you do indeed check 
their long term stability. 
The test is done in an indirect fashion so you only come up with a “it’s below 
the limit” sort of number. The
typical process involves running a group of OCXO’s on turn to check the 
frequency and then shifting them
off turn to make a sort of thermometer. After a few months of frequency 
readings you take them back to turn 
for a while. Relative frequency shift math gives you a stability number for the 
thermistor and the rest of the
circuitry. You may repeat the run for months / shift process a couple of times. 
If the answer isn’t “I can’t see 
a difference” you look for a new thermistor. Since it’s a long drawn out test, 
the tendency is to stick with a 
vendor’s part for quite a while. The parts also tend to be design specific so 
what works in my (say SMT)
design may not work well in your (say chip and wire) design. 

Bob

> On Jun 5, 2017, at 9:20 AM, romeo987  wrote:
> 
> Hi, guys
> I have been following time nuts and volt nuts for some time out of interest 
> and fascination. Although my personal backyard hobby is more along a volt 
> nuts line, the two worlds often collide - like in this discussion of 
> temperature sensors, and in particular their long term stability. NTC 
> thermistors appear to be very commonly used in ovens used to stabilize 
> voltage references (solid state as well as chemical) . I have long wondered 
> about their stability.  If, as Bruce asserts, "high quality thermistors can 
> achieve drifts of around 1mK/month" then it appears that this level of drift 
> is a significant factor in the "apparent" aging of, say, a bank of Weston 
> cells (which is still my best backyard shot at a voltage reference). 
> 
> I have had no luck with Google; Bruce's statement is the first quantified 
> allusion that I have seen to this subject.  Is there any actual data 
> available on the long term performance of NTC sensors?
> 
> Roman
> 
>> On 5 Jun 2017, at 9:53 AM, Bruce Griffiths  
>> wrote:
>> 
>> The other issue that needs to be considered is the drift in temperature 
>> sensor characteristics when operated at a constant temperature (as is 
>> typical in a continuously operated crystal oven). High quality thermistors 
>> can achieve drifts of around 1mK/month. Its unlikely that something as 
>> complex as an AD590 will achieve a similar drift (1nA/month in a operating 
>> current of 300uA or so at 25C). High quality PRT sensors drift even less 
>> than thermistors when operating at constant temperature.
>> 
>> Bruce
>> 
>>> 
>>>   .On 05 June 2017 at 11:59 Attila Kinali  wrote:
>>> 
>>>   Moin,
>>> 
>>>   This discussion is kind of getting heated.
>>>   Let's put some facts in, to steer it away from
>>>   opinion based discussion.
>>> 
>>>   On Sun, 4 Jun 2017 08:44:33 -0700
>>>   "Donald E. Pauly"  wrote:
>>> 
   I stand by my remark that thermistors have been obsolete for over 40
   years. The only exception that I know of is cesium beam tubes that
   must withstand a 350° C bakeout. Thermistors are unstable and
   manufactured with a witches brew straight out of MacBeth. Their
   output voltages are tiny and are they inconvenient to use at 
 different
   temperatures.
 
>>>   If you really mean thermistors, and not, as Bob suggested thermocouples,
>>>   then I have to disagree. The most stable temperature sensors are
>>>   platinum wire sensors. The standards class PRT's are the gold standard
>>>   when it comes to temperature measurement, for a quite wide range
>>>   (-260°C to +960°C) and are considered very stable. They offer (absolute)
>>>   accuracies in the order of 10mK in the temperature range below 400°C.
>>>   Even industrial grade PRT sensors give you an absolute accuracy better
>>>   than 0.1K up to 200-300°C. The "cheap" PT100 are more of the order of 
>>> 1-10°C
>>>   accuracy... all numbers just using a two-point calibration.
>>> 
>>>   For more information on this see [1] chapter 6 and [2] for industrial 
>>> sensors.
>>> 
>>>   NTC sensors have a higher variablity of their parameters in production
>>>   and are usually specified in % of temperature relative to their reference
>>>   point, which is usually 25°C. Typical values are 0.1% to 5%. Additionally
>>>   there is a deviation from the reference point, specified in °C, which
>>>   is usually in the order of 0.1°C to 1°C.
>>> 
>>>   The NTC sensors are less accurate than PT sensors, but offer the advantage
>>>   of higher resistance (thus lower self-heating), higher slope (thus better
>>>   precision). Biggest disadvantage is their non-linear curve. Their price
>>>   is also a fraction of PT sensors and due to that you can have them in
>>>   many different forms, from the 0201 SMD resistor, to a large stainless
>>>   steal pipe that goes into a chemical tank. NTCs are the workhorse in
>>>   todays temperature measurement and control designs.
>>> 

Re: [time-nuts] PPS sync

[Jerry Hancock]

It was off 7.5KM, that’s a little beyond groggy, no?  More like a trip to Vegas.

I’ll let it rerun the survey and see if it gets closer.

> On Jun 4, 2017, at 9:50 PM, Mark Sims  wrote:
> 
> Be careful when using one unit's location to set a different model's 
> location...  particularly the altitude.   Some devices report altitude in 
> MSL, others in AGL... and different units may use different models for the 
> ellipsoid.   You are always better off using coordinates generated by the 
> particular device (either the built-in self survey or something like Lady 
> Heather's precision survey).
> 
> I did some tests while developing Lady Heather's precision survey code.   I 
> got pretty consistent lat/lon/alt results on the same units but consistent 
> offsets between different models of receivers.
> 
> I would suggest letting the Motorola re-surevy itself...  it may have been a 
> bit groggy after first being powered up after a few years of sleep... I know 
> I am...
> 
> ---
> 
>> I then set the M12 reference location to the Lucent location as I know it to 
>> be correct.
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Re: [time-nuts] Temperature sensors and quartz crystals (was: HP5061B Versus HP5071 Cesium Line Frequencies)

[romeo987]

Hi, guys
I have been following time nuts and volt nuts for some time out of interest and 
fascination. Although my personal backyard hobby is more along a volt nuts 
line, the two worlds often collide - like in this discussion of temperature 
sensors, and in particular their long term stability. NTC thermistors appear to 
be very commonly used in ovens used to stabilize voltage references (solid 
state as well as chemical) . I have long wondered about their stability.  If, 
as Bruce asserts, "high quality thermistors can achieve drifts of around 
1mK/month" then it appears that this level of drift is a significant factor in 
the "apparent" aging of, say, a bank of Weston cells (which is still my best 
backyard shot at a voltage reference). 

I have had no luck with Google; Bruce's statement is the first quantified 
allusion that I have seen to this subject.  Is there any actual data available 
on the long term performance of NTC sensors?

Roman

> On 5 Jun 2017, at 9:53 AM, Bruce Griffiths  wrote:
> 
> The other issue that needs to be considered is the drift in temperature 
> sensor characteristics when operated at a constant temperature (as is typical 
> in a continuously operated crystal oven). High quality thermistors can 
> achieve drifts of around 1mK/month. Its unlikely that something as complex as 
> an AD590 will achieve a similar drift (1nA/month in a operating current of 
> 300uA or so at 25C). High quality PRT sensors drift even less than 
> thermistors when operating at constant temperature.
> 
> Bruce
> 
>> 
>>.On 05 June 2017 at 11:59 Attila Kinali  wrote:
>> 
>>Moin,
>> 
>>This discussion is kind of getting heated.
>>Let's put some facts in, to steer it away from
>>opinion based discussion.
>> 
>>On Sun, 4 Jun 2017 08:44:33 -0700
>>"Donald E. Pauly"  wrote:
>> 
>>>I stand by my remark that thermistors have been obsolete for over 40
>>>years. The only exception that I know of is cesium beam tubes that
>>>must withstand a 350° C bakeout. Thermistors are unstable and
>>>manufactured with a witches brew straight out of MacBeth. Their
>>>output voltages are tiny and are they inconvenient to use at 
>>> different
>>>temperatures.
>>> 
>>If you really mean thermistors, and not, as Bob suggested thermocouples,
>>then I have to disagree. The most stable temperature sensors are
>>platinum wire sensors. The standards class PRT's are the gold standard
>>when it comes to temperature measurement, for a quite wide range
>>(-260°C to +960°C) and are considered very stable. They offer (absolute)
>>accuracies in the order of 10mK in the temperature range below 400°C.
>>Even industrial grade PRT sensors give you an absolute accuracy better
>>than 0.1K up to 200-300°C. The "cheap" PT100 are more of the order of 
>> 1-10°C
>>accuracy... all numbers just using a two-point calibration.
>> 
>>For more information on this see [1] chapter 6 and [2] for industrial 
>> sensors.
>> 
>>NTC sensors have a higher variablity of their parameters in production
>>and are usually specified in % of temperature relative to their reference
>>point, which is usually 25°C. Typical values are 0.1% to 5%. Additionally
>>there is a deviation from the reference point, specified in °C, which
>>is usually in the order of 0.1°C to 1°C.
>> 
>>The NTC sensors are less accurate than PT sensors, but offer the advantage
>>of higher resistance (thus lower self-heating), higher slope (thus better
>>precision). Biggest disadvantage is their non-linear curve. Their price
>>is also a fraction of PT sensors and due to that you can have them in
>>many different forms, from the 0201 SMD resistor, to a large stainless
>>steal pipe that goes into a chemical tank. NTCs are the workhorse in
>>todays temperature measurement and control designs.
>> 
>>The next category are band-gap sensors like the AD590. Their biggest
>>advantage is that their 0 point is fix at 0K (and very accurately so).
>>Ie they can be used with single point calibration and achieve 1°C accuracy
>>this way. Their biggest drawback their large thermal mass and large
>>insulating case, because they are basically an standard, analog IC.
>>Ie their main use is in devices where there is a lot of convection and
>>slow temperature change. Due to their simple and and quite linear
>>characteristics, they are often used in purely analog temperature
>>control circuits, or where a linearization is not feasible.
>>But only if price isn't an issue (they cost 10-1000 times as
>>much as an PTC). Their biggest disadvantage, beside their slow
>>thermal raction time, is their large noise uncorrelated to the
>>supply voltage, and thus cannot be compensated by ratiometric measurement.
>>They are also more suceptible to mechanical stress than NTC's and PT's,
>>due to their construction. Sim

Re: [time-nuts] Poor man's oven

[Adrian Godwin]

Wax is also used for thermostatic valves in engine cooling systems and
domestic heating systems.

On Mon, Jun 5, 2017 at 1:13 PM, Tim Shoppa  wrote:

> Here is a national new-technology of the art crystal oven from 1956:
>
> http://tf.boulder.nist.gov/general/pdf/1642.pdf
>
> Using the phase change properties of p-dibromobenzene it keeps temperature
> constant to 0.01C. It notes other organic compounds can be used for
> different temperature ranges.
>
> Did this oven technology ever get beyond lab use and into the real crystal
> oven world?
>
> I know in the past decade "thermowax" has been used in Honda lawnmower
> auto-chokes. I don't think it's ever supposed to be anything but solid, but
> it undergoes a phase change that causes it to expand by a large fraction.
>
> Tim N3QE
>
>
>
> Sent from my VAX-11/780
> > On Jun 5, 2017, at 5:16 AM, Clint Jay  wrote:
> >
> > There's a few 'OCXO' designs out there, I'm not qualified to comment on
> the
> > timenutty quality of them but someone else mentioned Hans Summers
> offerings
> > and I would offer Roman Black's simple design (if it's not been mentioned
> > already):
> >
> > http://www.romanblack.com/xoven.htm
> >
> > I've no idea if it's useful but it's ridiculously simple to implement.
> >
> > Both Hans' and Roman's designs are 'on the list' of things to try for
> > myself at some point.
> >
> >> On 5 June 2017 at 09:56, Stephen Tompsett  wrote:
> >>
> >> Not quite as simple as the PTC, an alternative may be:
> >>
> >> http://shop.kuhne-electronic.de/kuhne/en/shop/accessoires/
> >> crystal-heater/Precision+crystal+heater+40%C2%B0+QH40A/?card=724
> >>
> >> No it probably doesn't hold the crystal at it's optimum turn over
> >> temperature, but it will keep the temperature of a crystal approximately
> >> constant especially on a windswept hilltop.
> >>
> >>
> >>> On 05/06/2017 09:35, Ulf Kylenfall via time-nuts wrote:
> >>>  The Crystal heater clip wasa Murata "Posistor" soldered onto a clipand
> >> they were marketed by Murata.
> >>> I once purchased a small amount of theseand used them as "poor man's
> >> ovens".
> >>> Although not perfect by far, they did theirjob and kept my UHF gear
> >> stable.
> >>> Murata dropped that product many yearsago and I have not been able to
> >> findany similar product. The Posistors arelisted by eg. Digi-key but
> they
> >> do not stock them.
> >>> Ulf - SM6GXV
> >>>
> >>> ___
> >>> 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.
> >>>
> >>
> >> --
> >> Stephen Tompsett
> >>
> >> ___
> >> 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.
> >>
> >
> >
> >
> > --
> > Clint.
> >
> > *No trees were harmed in the sending of this mail. However, a large
> number
> > of electrons were greatly inconvenienced.*
> > ___
> > time-nuts mailing list -- time-nuts@febo.com
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> mailman/listinfo/time-nuts
> > and follow the instructions there.
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Re: [time-nuts] poor-man's oven

[jimlux]

On 6/4/17 10:01 PM, Chris Albertson wrote:

Voltage is proportional to the product of resistance and absolute
temperature.   As an experiment place a voltage across a high value
resister like say one 1M  raise the volts until you are near the limit of
the resister and connect it via a coupler cadaster to an audio amplifier.
You will hear white noise in the speakers.


As in Johnson noise - vrms = sqrt(4kTR)



There is a similar effect in semi conductors.  The best example of this is
visual noise in digital camera, when you tern the gain way up (set the ISO
high) you can see it in the photo.


I believe that's a different mechanism, shot noise.



All of this is proportion; to absolute.

As I remember we ran the "oven" at -20C There was a valve used to flash out
the air inside with inert welding gas to reduce ice.

Some people use vacuum and get to cryogenic temperatures.  But that is
expensive and way-hard without an institutional size budget.




cryogenic (as in LN2 temps) is very hard with TEC it takes many stacked 
devices that wind up looking like a ziggurat.


near vacuum isn't that tough at home - refrigeration vacuum pumps are 
inexpensive.  If it's a one time thing, a sorption pump and one time Ln2 
or Dry Ice can get you pretty empty as a one shot. Then you seal it off 
and it's done.
the Bell Jar - http://www.belljar.net/  is a handy reference of vacuum 
hacking stuff








What is the reason why you'd expect less noise with a TEC?

Attila Kinali

--
You know, the very powerful and the very stupid have one thing in common.
They don't alters their views to fit the facts, they alter the facts to
fit the views, which can be uncomfortable if you happen to be one of the
facts that needs altering.  -- The Doctor
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Re: [time-nuts] Poor man's oven

[Tim Shoppa]

Here is a national new-technology of the art crystal oven from 1956: 

http://tf.boulder.nist.gov/general/pdf/1642.pdf

Using the phase change properties of p-dibromobenzene it keeps temperature 
constant to 0.01C. It notes other organic compounds can be used for different 
temperature ranges.

Did this oven technology ever get beyond lab use and into the real crystal oven 
world?

I know in the past decade "thermowax" has been used in Honda lawnmower 
auto-chokes. I don't think it's ever supposed to be anything but solid, but it 
undergoes a phase change that causes it to expand by a large fraction.

Tim N3QE



Sent from my VAX-11/780
> On Jun 5, 2017, at 5:16 AM, Clint Jay  wrote:
> 
> There's a few 'OCXO' designs out there, I'm not qualified to comment on the
> timenutty quality of them but someone else mentioned Hans Summers offerings
> and I would offer Roman Black's simple design (if it's not been mentioned
> already):
> 
> http://www.romanblack.com/xoven.htm
> 
> I've no idea if it's useful but it's ridiculously simple to implement.
> 
> Both Hans' and Roman's designs are 'on the list' of things to try for
> myself at some point.
> 
>> On 5 June 2017 at 09:56, Stephen Tompsett  wrote:
>> 
>> Not quite as simple as the PTC, an alternative may be:
>> 
>> http://shop.kuhne-electronic.de/kuhne/en/shop/accessoires/
>> crystal-heater/Precision+crystal+heater+40%C2%B0+QH40A/?card=724
>> 
>> No it probably doesn't hold the crystal at it's optimum turn over
>> temperature, but it will keep the temperature of a crystal approximately
>> constant especially on a windswept hilltop.
>> 
>> 
>>> On 05/06/2017 09:35, Ulf Kylenfall via time-nuts wrote:
>>>  The Crystal heater clip wasa Murata "Posistor" soldered onto a clipand
>> they were marketed by Murata.
>>> I once purchased a small amount of theseand used them as "poor man's
>> ovens".
>>> Although not perfect by far, they did theirjob and kept my UHF gear
>> stable.
>>> Murata dropped that product many yearsago and I have not been able to
>> findany similar product. The Posistors arelisted by eg. Digi-key but they
>> do not stock them.
>>> Ulf - SM6GXV
>>> 
>>> ___
>>> 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.
>>> 
>> 
>> --
>> Stephen Tompsett
>> 
>> ___
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>> mailman/listinfo/time-nuts
>> and follow the instructions there.
>> 
> 
> 
> 
> -- 
> Clint.
> 
> *No trees were harmed in the sending of this mail. However, a large number
> of electrons were greatly inconvenienced.*
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Re: [time-nuts] Temperature sensors and quartz crystals (was: HP5061B Versus HP5071 Cesium Line Frequencies)

[Bob kb8tq]

Hi

> On Jun 5, 2017, at 7:30 AM, Attila Kinali  wrote:
> 
> On Mon, 5 Jun 2017 01:18:59 +0100
> Adrian Godwin  wrote:
> 
>> Where do digital sensors (e.g. ds1820 and some more recent parts from TI)
>> fit into this ?
> 
> AFAIK, these are all band-gap temperature sensors. But unlike a discrete
> sensor, you have the problem that they only contain a low resolution
> ADC on die (somewhere between 8 and 14 bit). If your goal is to measure
> temperature and report it with an accuracy of about 1°C, then these are
> the easiest to use sensors you can buy. Sensor noise doesn't really matter
> with them, as it is dominated by the low ADC resolution. I don't have any
> long term stability data on those, but given their use-case I do not think
> that they are very stable.

Based on using them in a lot of designs, they are indeed quite stable. They are 
not
going to rival a thermistor or an RTD, but compared to their resolution they 
are stable. 
Put another way, if they read out at the (say) 0.5 C level, you can come back a 
year later 
and the temperature repeats at < the 0.5 C level. 

None of this is simple or straightforward. All temperature sensors have a 
sensitivity 
to strain. They all exhibit some level of hysteresis.  That can make aging 
measurements 
a bit challenging. 

Bob


> Although long term stability might not be an
> issue at all, again due to low ADC resolution.
> 
> 
> If you need better precision, accuracy, or stability, then choosing one
> of the modern delta-sigma ADCs that directly support thermistors
> (e.g. like AD7124) is not much more difficult, though a bit more expensive
> (around 10USD instead of 5USD like for an TMP107). Additionally you need
> to calbirate the system, which means you need a reference temperature sensor
> and a setup with which you can produce different temperatures. Though for
> an oven kind of temperature control, one can live without calibration.
> 
> 
>   Attila Kinali
> -- 
> You know, the very powerful and the very stupid have one thing in common.
> They don't alters their views to fit the facts, they alter the facts to
> fit the views, which can be uncomfortable if you happen to be one of the
> facts that needs altering.  -- The Doctor
> ___
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> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
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Re: [time-nuts] Temperature sensors and quartz crystals (was: HP5061B Versus HP5071 Cesium Line Frequencies)

[Attila Kinali]

On Mon, 5 Jun 2017 01:18:59 +0100
Adrian Godwin  wrote:

> Where do digital sensors (e.g. ds1820 and some more recent parts from TI)
> fit into this ?

AFAIK, these are all band-gap temperature sensors. But unlike a discrete
sensor, you have the problem that they only contain a low resolution
ADC on die (somewhere between 8 and 14 bit). If your goal is to measure
temperature and report it with an accuracy of about 1°C, then these are
the easiest to use sensors you can buy. Sensor noise doesn't really matter
with them, as it is dominated by the low ADC resolution. I don't have any
long term stability data on those, but given their use-case I do not think
that they are very stable. Although long term stability might not be an
issue at all, again due to low ADC resolution.


If you need better precision, accuracy, or stability, then choosing one
of the modern delta-sigma ADCs that directly support thermistors
(e.g. like AD7124) is not much more difficult, though a bit more expensive
(around 10USD instead of 5USD like for an TMP107). Additionally you need
to calbirate the system, which means you need a reference temperature sensor
and a setup with which you can produce different temperatures. Though for
an oven kind of temperature control, one can live without calibration.


Attila Kinali
-- 
You know, the very powerful and the very stupid have one thing in common.
They don't alters their views to fit the facts, they alter the facts to
fit the views, which can be uncomfortable if you happen to be one of the
facts that needs altering.  -- The Doctor
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Re: [time-nuts] Poor man's oven

[Bob kb8tq]

Hi

The posistor approach to heating a crystal was originally pioneered in Russia. 
Morion was 
building vacuum insulated / PTC controlled OCXO’s long before the PTC parts 
started showing
up more generally in the 1970’s. 

Bob

> On Jun 5, 2017, at 4:35 AM, Ulf Kylenfall via time-nuts  
> wrote:
> 
>   The Crystal heater clip wasa Murata "Posistor" soldered onto a clipand they 
> were marketed by Murata.
> I once purchased a small amount of theseand used them as "poor man's ovens".
> Although not perfect by far, they did theirjob and kept my UHF gear stable.
> Murata dropped that product many yearsago and I have not been able to findany 
> similar product. The Posistors arelisted by eg. Digi-key but they do not 
> stock them.
> Ulf - SM6GXV
> 
> ___
> 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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Re: [time-nuts] Temperature sensors and quartz crystals (was: HP5061B Versus HP5071 Cesium Line Frequencies)

[Bob kb8tq]

Hi

If your objective is a resolution of < 0.001 C at something < 1 second, the 
current crop of 
digital sensors don’t quite do what you need to do. They are a terrific way to 
do wide range 
measurements that might feed into some sort of correction algorithm. A 
conventional 
thermistor bridge falls apart if you try to run it -55 to +125. The range of 
resistances 
involved results in significantly lowered resolution at the end(s) of the 
range. 

Bob

> On Jun 4, 2017, at 8:18 PM, Adrian Godwin  wrote:
> 
> Where do digital sensors (e.g. ds1820 and some more recent parts from TI)
> fit into this ?
> 
> 
> On Mon, Jun 5, 2017 at 12:59 AM, Attila Kinali  wrote:
> 
>> Moin,
>> 
>> This discussion is kind of getting heated.
>> Let's put some facts in, to steer it away from
>> opinion based discussion.
>> 
>> On Sun, 4 Jun 2017 08:44:33 -0700
>> "Donald E. Pauly"  wrote:
>> 
>>> I stand by my remark that thermistors have been obsolete for over 40
>>> years.  The only exception that I know of is cesium beam tubes that
>>> must withstand a 350° C bakeout.  Thermistors are unstable and
>>> manufactured with a witches brew straight out of MacBeth.  Their
>>> output voltages are tiny and are they inconvenient to use at different
>>> temperatures.
>> 
>> If you really mean thermistors, and not, as Bob suggested thermocouples,
>> then I have to disagree. The most stable temperature sensors are
>> platinum wire sensors. The standards class PRT's are the gold standard
>> when it comes to temperature measurement, for a quite wide range
>> (-260°C to +960°C) and are considered very stable. They offer (absolute)
>> accuracies in the order of 10mK in the temperature range below 400°C.
>> Even industrial grade PRT sensors give you an absolute accuracy better
>> than 0.1K up to 200-300°C. The "cheap" PT100 are more of the order of
>> 1-10°C
>> accuracy... all numbers just using a two-point calibration.
>> 
>> For more information on this see [1] chapter 6 and [2] for industrial
>> sensors.
>> 
>> NTC sensors have a higher variablity of their parameters in production
>> and are usually specified in % of temperature relative to their reference
>> point, which is usually 25°C. Typical values are 0.1% to 5%. Additionally
>> there is a deviation from the reference point, specified in °C, which
>> is usually in the order of 0.1°C to 1°C.
>> 
>> The NTC sensors are less accurate than PT sensors, but offer the advantage
>> of higher resistance (thus lower self-heating), higher slope (thus better
>> precision). Biggest disadvantage is their non-linear curve. Their price
>> is also a fraction of PT sensors and due to that you can have them in
>> many different forms, from the 0201 SMD resistor, to a large stainless
>> steal pipe that goes into a chemical tank. NTCs are the workhorse in
>> todays temperature measurement and control designs.
>> 
>> The next category are band-gap sensors like the AD590. Their biggest
>> advantage is that their 0 point is fix at 0K (and very accurately so).
>> Ie they can be used with single point calibration and achieve 1°C accuracy
>> this way. Their biggest drawback their large thermal mass and large
>> insulating case, because they are basically an standard, analog IC.
>> Ie their main use is in devices where there is a lot of convection and
>> slow temperature change. Due to their simple and and quite linear
>> characteristics, they are often used in purely analog temperature
>> control circuits, or where a linearization is not feasible.
>> But only if price isn't an issue (they cost 10-1000 times as
>> much as an PTC). Their biggest disadvantage, beside their slow
>> thermal raction time, is their large noise uncorrelated to the
>> supply voltage, and thus cannot be compensated by ratiometric measurement.
>> They are also more suceptible to mechanical stress than NTC's and PT's,
>> due to their construction. Similar to voltage references (which they
>> actually are), their aging is quite substantial and cannot be neglected
>> in precision application.
>> With a 3 point calibration, better than 0.5°C accuracy can be achieved
>> (modulo aging) within their operating temperature range, which is
>> rather limited, compared to the other sensor types.
>> 
>> I don't know enough about thermocouples to say much about them, beside
>> that they are cumbersome to work with (e.g. the cold contact) and
>> produce a low voltage (several µV) output with quite high impedance,
>> which makes the analog electronics difficult to design as well.
>> 
>> 
>> With todays electronics, the easiest sensors to work with are NTC and
>> PT100/PT1000 as most high resolution delta-sigma ADCs have direct support
>> for 3 and/or 4 wire measurement of those, including compensation for
>> reference voltage/current variation. Using a uC as control element
>> also opens up the possibility to linearize the curve of NTCs without
>> loss of accuracy. Usually measurement precision, with a state-of-the-art
>> circuit, is limited by noise 

[time-nuts] PPS sync

[Mark Sims]

Be careful when using one unit's location to set a different model's 
location...  particularly the altitude.   Some devices report altitude in MSL, 
others in AGL... and different units may use different models for the 
ellipsoid.   You are always better off using coordinates generated by the 
particular device (either the built-in self survey or something like Lady 
Heather's precision survey).

I did some tests while developing Lady Heather's precision survey code.   I got 
pretty consistent lat/lon/alt results on the same units but consistent offsets 
between different models of receivers.

I would suggest letting the Motorola re-surevy itself...  it may have been a 
bit groggy after first being powered up after a few years of sleep... I know I 
am...

---

> I then set the M12 reference location to the Lucent location as I know it to 
> be correct.
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Re: [time-nuts] Poor man's oven

[Clint Jay]

There's a few 'OCXO' designs out there, I'm not qualified to comment on the
timenutty quality of them but someone else mentioned Hans Summers offerings
and I would offer Roman Black's simple design (if it's not been mentioned
already):

http://www.romanblack.com/xoven.htm

I've no idea if it's useful but it's ridiculously simple to implement.

Both Hans' and Roman's designs are 'on the list' of things to try for
myself at some point.

On 5 June 2017 at 09:56, Stephen Tompsett  wrote:

> Not quite as simple as the PTC, an alternative may be:
>
> http://shop.kuhne-electronic.de/kuhne/en/shop/accessoires/
> crystal-heater/Precision+crystal+heater+40%C2%B0+QH40A/?card=724
>
> No it probably doesn't hold the crystal at it's optimum turn over
> temperature, but it will keep the temperature of a crystal approximately
> constant especially on a windswept hilltop.
>
>
> On 05/06/2017 09:35, Ulf Kylenfall via time-nuts wrote:
> >   The Crystal heater clip wasa Murata "Posistor" soldered onto a clipand
> they were marketed by Murata.
> > I once purchased a small amount of theseand used them as "poor man's
> ovens".
> > Although not perfect by far, they did theirjob and kept my UHF gear
> stable.
> > Murata dropped that product many yearsago and I have not been able to
> findany similar product. The Posistors arelisted by eg. Digi-key but they
> do not stock them.
> > Ulf - SM6GXV
> >
> > ___
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> Stephen Tompsett
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-- 
Clint.

*No trees were harmed in the sending of this mail. However, a large number
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Re: [time-nuts] poor-man's oven

[Attila Kinali]

On Sun, 4 Jun 2017 22:01:45 -0700
Chris Albertson  wrote:

> Voltage is proportional to the product of resistance and absolute
> temperature.   As an experiment place a voltage across a high value
> resister like say one 1M  raise the volts until you are near the limit of
> the resister and connect it via a coupler cadaster to an audio amplifier.
> You will hear white noise in the speakers.

Yes, Johnson noise increases by about 20% (or about 0.8dB)
when going from 25°C to 90°C. But Johnson noise is usually
not the first limiting noise one runs into when designing
a crystal oscillator. I would rather use a simpler,
"high temperature" oven and invest the time saved into a
desgining better oscillator structure.


> There is a similar effect in semi conductors.  The best example of this is
> visual noise in digital camera, when you tern the gain way up (set the ISO
> high) you can see it in the photo.
> 
> All of this is proportion; to absolute.
> 
> As I remember we ran the "oven" at -20C There was a valve used to flash out
> the air inside with inert welding gas to reduce ice.

If the -20°C was used on the camera, then this is not to reduce Johnson
noise, but the dark current noise. While the former is due to thermal
vibration of the atom lattice, the later is due to spontaneous forming
of electron-hole pairs in the p-n junction region. Thus also their
temperature characteristics differ: While Johnson noise is linear
in temperature, dark current noise is (almost) exponential in temperature.
Going down from room temperature to 0°C is something like a factor 100
(IIRC, from memory, could be wrong) in noise for a CCD. While for
a resistor, the difference is almost negligible.

Attila Kinali
-- 
You know, the very powerful and the very stupid have one thing in common.
They don't alters their views to fit the facts, they alter the facts to
fit the views, which can be uncomfortable if you happen to be one of the
facts that needs altering.  -- The Doctor
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Re: [time-nuts] Poor man's oven

[Stephen Tompsett]

Not quite as simple as the PTC, an alternative may be:

http://shop.kuhne-electronic.de/kuhne/en/shop/accessoires/crystal-heater/Precision+crystal+heater+40%C2%B0+QH40A/?card=724

No it probably doesn't hold the crystal at it's optimum turn over
temperature, but it will keep the temperature of a crystal approximately
constant especially on a windswept hilltop.


On 05/06/2017 09:35, Ulf Kylenfall via time-nuts wrote:
>   The Crystal heater clip wasa Murata "Posistor" soldered onto a clipand they 
> were marketed by Murata.
> I once purchased a small amount of theseand used them as "poor man's ovens".
> Although not perfect by far, they did theirjob and kept my UHF gear stable.
> Murata dropped that product many yearsago and I have not been able to findany 
> similar product. The Posistors arelisted by eg. Digi-key but they do not 
> stock them.
> Ulf - SM6GXV
>
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-- 
Stephen Tompsett

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[time-nuts] Poor man's oven

[Ulf Kylenfall via time-nuts]

  The Crystal heater clip wasa Murata "Posistor" soldered onto a clipand they 
were marketed by Murata.
I once purchased a small amount of theseand used them as "poor man's ovens".
Although not perfect by far, they did theirjob and kept my UHF gear stable.
Murata dropped that product many yearsago and I have not been able to findany 
similar product. The Posistors arelisted by eg. Digi-key but they do not stock 
them.
Ulf - SM6GXV

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