Re: [time-nuts] PPS sync

[Chris Albertson]

One of the GPS units is likely sending a saw-tooth message out the serial
line that exactly describes the 0 to 100ns drift.   This is why they call
it "saw tooth" the function ramps up slowly then falls to zero.  A device
like a GPSDO that uses the PPS would need access to the serial data to read
the sawtooth correction,

On Sun, Jun 4, 2017 at 9:36 PM, Jerry Hancock  wrote:

> 1) I have my TAPR M12 Kit working now next to my lucent RFTG-U REF0/1
> pair.  I was comparing the PPS outputs triggering on the Lucent as channel
> 1 and the M12 as channel 2.  I can’t tell which is moving around but the
> symptoms are that at T0 (not the top of the minute or hour) they are in
> sync within a nanosecond.  From T1 to T20 they move progressively out of
> sync until hitting around 100ns and then snapping back to being in sync. I
> would think that if both were moving that it wouldn’t be that consistent,
> no?
>
> Since I can’t tell which is moving, most likely both,  I plan to take the
> disciplined 10Mhz out of the Lucent and divide it down with my TAPR TADD-2
> to 1PPS.  I would think that would be more stable on a PPS by PPS basis and
> compare again.
>
> Any other ideas?
>
> 2)  When I first fired up the M12 and let it do a survey, it was off for
> some reason by 7KM.  I then set the M12 reference location to the Lucent
> location as I know it to be correct.  I was thinking though, would the PPS
> phase comparison in 1, above, be impacted by the reference locations being
> off?  Both GPS cables are the same length.  The only thing I don’t know is
> the internal processing delay of the units.  The SynTac software allows you
> to take this into consideration for PPS timing when using the M12.
> Interesting unit by the way.  Lots of configuration options exposed with
> the Syntac software.  Not that I would replace Lady Heather or anything,
> I’m just using it while I get some of these issues figured out.
>
> Jerry
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-- 

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

[Chris Albertson]

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.

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.

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





> 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
> ___
> 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.
>



-- 

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

[Jerry Hancock]

1) I have my TAPR M12 Kit working now next to my lucent RFTG-U REF0/1 pair.  I 
was comparing the PPS outputs triggering on the Lucent as channel 1 and the M12 
as channel 2.  I can’t tell which is moving around but the symptoms are that at 
T0 (not the top of the minute or hour) they are in sync within a nanosecond.  
From T1 to T20 they move progressively out of sync until hitting around 100ns 
and then snapping back to being in sync. I would think that if both were moving 
that it wouldn’t be that consistent, no?

Since I can’t tell which is moving, most likely both,  I plan to take the 
disciplined 10Mhz out of the Lucent and divide it down with my TAPR TADD-2 to 
1PPS.  I would think that would be more stable on a PPS by PPS basis and 
compare again. 

Any other ideas?

2)  When I first fired up the M12 and let it do a survey, it was off for some 
reason by 7KM.  I then set the M12 reference location to the Lucent location as 
I know it to be correct.  I was thinking though, would the PPS phase comparison 
in 1, above, be impacted by the reference locations being off?  Both GPS cables 
are the same length.  The only thing I don’t know is the internal processing 
delay of the units.  The SynTac software allows you to take this into 
consideration for PPS timing when using the M12.  Interesting unit by the way.  
Lots of configuration options exposed with the Syntac software.  Not that I 
would replace Lady Heather or anything, I’m just using it while I get some of 
these issues figured out.

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

[Adrian Godwin]

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 coupling into the leads of the sensor
> and noise in and around the ADC. (see [3-5])
>
>
> > Where did you get the idea to use a 1 k load for an AD590?
>
> Jim was refering to a circuit _he_ used in a satellite. Not to your
> circuit.
>
> > The room temperature coefficient of an AT crystal is -cd 100 ppb per
> > reference cut angle in minutes.  (-600 ppb/C° for standard crystal)
> > The practical limit in a crystal designed for room temperature is
> > about 0.1' cut accuracy or ±10 ppb/C°.  If you have access to an
> > atomic standard, you can use feed forward 

Re: [time-nuts] TAPR GPS Experimenters Kit

[Hal Murray]

trojancow...@gmail.com said:
>  A roof antenna with preamp that could drive 100 feet or so of foam RG-58 is
> required.

RG-58 is very lossy at GPS signal frequencies.

The sweet spot on the cost/performance chart is RG-6.  It's widely available 
as low loss cable TV.  It's slightly larger diameter than RG-59.  It's 75 
ohms, but the loss due to mismatch is small relative to the cable loss.


-- 
These are my opinions.  I hate spam.



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

[Bruce Griffiths]

Yes, I have a TEC mounted on a convection heatsink that illustrates that point.
Initially ice forms on the cold surface but eventually the heatsink temperature 
rises sufficiently that the ice melts. A larger blown heatsink or perhaps a 
water cooled heatsink would be necessary if this setup was intended for 
anything other than a demonstration of this issue.

Bruce  

> On 05 June 2017 at 13:58 Bob kb8tq  wrote:
> 
> 
> Hi
> 
> Many times people underestimate the amount of heat sinking required with a 
> TEC. If you get into fans, they 
> introduce a whole new set of issues ….It’s not just the heat you are getting 
> out of the “oven”. The TEC it’s self
> makes a pretty good thermal short (compared to foam insulation). You have to 
> “pump” across that as well. 
> 
> Bob
> 
> > On Jun 4, 2017, at 9:38 PM, Ellen Franke  wrote:
> > 
> > My concern with using a TEC is that, heating or cooling, you are left with 
> > one cold surface and that surface will collect condensation which is a 
> > source for corrosion.
> > John WA4WDL
> > 
> > 
> >> On June 4, 2017 at 8:12 PM Attila Kinali  wrote:
> >> 
> >> 
> >> Moin Chris,
> >> 
> >> On Sun, 4 Jun 2017 13:49:29 -0700
> >> Chris Albertson  wrote:
> >> 
> >>> We used the pelter because we preferred a cool "oven" to a hot one.   The
> >>> theory has that we get less electronic noise so we ran the TEC in cooling
> >>> mode.   But for your use a resistive heater would be cheaper.   But in
> >>> either case you see a coffee mug with a round chunk of Al shoved in and
> >>> heat sink fins showing.
> >> 
> >> 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
> >> ___
> >> 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.
> > ___
> > 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] HP 3048 NI GP-IB cards help requested

[John Miles]

I'd recommend a GPIB-USB-HS adapter.  There are tons of them on eBay, e.g.

http://www.ebay.com/itm/322360711342 
http://www.ebay.com/itm/321957086926 

These will work well with both PN3048 and HTBasic.  I've purchased them from 
both of those sellers in the past.  They appear to be genuine, unlike the 
counterfeit Agilent 82357Bs that are commonly sold out of China.

Re: the card selection option, PN3048 lets you choose between "Adapter 1" and 
"Adapter 2."  This only comes into play if you have more than one NI adapter on 
your PC.  In your case, you'll use the default Adapter 1 setting with it.

You can also use a NI PCI-GPIB board with either PN3048 or HTBasic.  I'd go 
with the GPIB-USB-HS even though it may be a bit more expensive.  It will be 
more future-proof than a plug-in card.

-- john, KE5FX
Miles Design LLC


> HOWEVER, I don't have a GP-IB card.  According to
> KE5FX, both the bus card and USB dongle types work.
> It looks like current NI driver supports many
> legacy cards.  I am curious about whether this
> means that all of these cards will be OK, or if I
> have to buy the latest card/dongle?  I would like
> to be able to run both programs.  The HT Basic
> site says that certain bus chips are incompatible
> with its software, and I should call them for suggestions.
> 

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

[Bob kb8tq]

Hi

Many times people underestimate the amount of heat sinking required with a TEC. 
If you get into fans, they 
introduce a whole new set of issues ….It’s not just the heat you are getting 
out of the “oven”. The TEC it’s self
makes a pretty good thermal short (compared to foam insulation). You have to 
“pump” across that as well. 

Bob

> On Jun 4, 2017, at 9:38 PM, Ellen Franke  wrote:
> 
> My concern with using a TEC is that, heating or cooling, you are left with 
> one cold surface and that surface will collect condensation which is a source 
> for corrosion.
> John WA4WDL
> 
> 
>> On June 4, 2017 at 8:12 PM Attila Kinali  wrote:
>> 
>> 
>> Moin Chris,
>> 
>> On Sun, 4 Jun 2017 13:49:29 -0700
>> Chris Albertson  wrote:
>> 
>>> We used the pelter because we preferred a cool "oven" to a hot one.   The
>>> theory has that we get less electronic noise so we ran the TEC in cooling
>>> mode.   But for your use a resistive heater would be cheaper.   But in
>>> either case you see a coffee mug with a round chunk of Al shoved in and
>>> heat sink fins showing.
>> 
>> 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
>> ___
>> 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

[jimlux]

On 6/4/17 4:59 PM, Attila Kinali wrote:




Where did you get the idea to use a 1 k load for an AD590?


Jim was refering to a circuit _he_ used in a satellite. Not to your circuit.



We've also used 3k.  It's more about supply voltage, expected 
temperature range, and the ADC you're using (if any). 1k is handy if 
you're running off 5V and are feeding a 1 volt full scale ADC - room 
temp is 0.3 V.  Note that the *minimum* voltage across an AD590 is 4V, 
so if you've got a 3V supply, you're out of luck.


10k gives you 3V at room temp, and is quite ok into a 5V ADC, as long as 
your supply is at least 7-8 volts.


There is self heating to worry about if you have a high supply voltage 
(12V @ 0.3 mA is 3.6 mW), but realistically, all sensors have that 
problem (unless you are using a PRT in some sort of bridge that nulls 
the current)



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

[Bruce Griffiths]

Really??

The circuitry employed is something of a joke surely?

Relying on the   MOSFET characteristics to limit warm up current is unwise.

The temperature sensor also would appear to suffer from large variations in 
output from one part to another.

Bruce

> 
> On 05 June 2017 at 01:21 "R. Kuehn"  wrote:
> 
> Maybe you want to check out the work of Hans Summers he has done some
> impressive low cost stuff:
> http://www.hanssummers.com/ocxosynth.html
> http://www.qrp-labs.com/ocxokit.html
> 
> Ralph
> 
> On Sun, Jun 4, 2017 at 07:19 jimlux  wrote:
> 
> > > 
> > I recall some years ago folks were talking about putting a PTC
> > thermistor on the TCXO of a FlexRadio SDR1000 to stabilize the 
> > frequency
> > as a sort of poor-man's OCXO.
> > It's also referenced at
> > http://www.setileague.org/askdr/xtaloven.htm
> > where he says "order of magnitude improvement" with no numbers 
> > (from 1%
> > to 0.1% or from 1 ppb to 0.1 ppb?)
> > 
> > I wonder how well that actually works.
> > 
> > Say you bought an inexpensive (perhaps non TC) XO and an equally
> > inexpensive thermistor, glued on on the other, hooked em both up to 
> > 3.3
> > or 5V.
> > 
> > Yeah, there's issues with room air blowing on it, and tolerances in 
> > both
> > the XO and thermistor, so your absolute frequency accuracy may not 
> > be so
> > hot. But what sort of medium to long term performance can one 
> > expect.
> > 
> > I did some searches, because I'm sure we've discussed this before, 
> > but I
> > couldn't find it. There was some stuff from Oct 2007, but that was 
> > in
> > the context of a more complex circuit, and the thermistor was the
> > sensor. (discussions of TE devices too)
> > 
> > ___
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> > > 
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Re: [time-nuts] poor-man's oven

[Ellen Franke]

My concern with using a TEC is that, heating or cooling, you are left with one 
cold surface and that surface will collect condensation which is a source for 
corrosion.
John WA4WDL


> On June 4, 2017 at 8:12 PM Attila Kinali  wrote:
> 
> 
> Moin Chris,
> 
> On Sun, 4 Jun 2017 13:49:29 -0700
> Chris Albertson  wrote:
> 
> > We used the pelter because we preferred a cool "oven" to a hot one.   The
> > theory has that we get less electronic noise so we ran the TEC in cooling
> > mode.   But for your use a resistive heater would be cheaper.   But in
> > either case you see a coffee mug with a round chunk of Al shoved in and
> > heat sink fins showing.
> 
> 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
> ___
> 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)

[Bruce Griffiths]

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. 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 

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

[Attila Kinali]

Moin Chris,

On Sun, 4 Jun 2017 13:49:29 -0700
Chris Albertson  wrote:

> We used the pelter because we preferred a cool "oven" to a hot one.   The
> theory has that we get less electronic noise so we ran the TEC in cooling
> mode.   But for your use a resistive heater would be cheaper.   But in
> either case you see a coffee mug with a round chunk of Al shoved in and
> heat sink fins showing.

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

[Attila Kinali]

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 coupling into the leads of the sensor
and noise in and around the ADC. (see [3-5])

 
> Where did you get the idea to use a 1 k load for an AD590?  

Jim was refering to a circuit _he_ used in a satellite. Not to your circuit.

> The room temperature coefficient of an AT crystal is -cd 100 ppb per
> reference cut angle in minutes.  (-600 ppb/C° for standard crystal)
> The practical limit in a crystal designed for room temperature is
> about 0.1' cut accuracy or ±10 ppb/C°.  If you have access to an
> atomic standard, you can use feed forward to get ±1 ppb/C°.  If the
> temperature can be held to ±0.001° C, this is ±1 part per trillion.
> This kind of accuracy has never been heard of.

It has been heard of. The 8607 was spec'ed to <2e-10 p-p deviation
over temperature range (-30°C to 60°C). Also, to hold the temperature
stable to 0.001K in a room temperature 

Re: [time-nuts] HP5061B Versus HP5071 Cesium Line Frequencies

[Bob kb8tq]

Hi

A thermistor has *no* output unless it is in a circuit that biases it up. A 
thermocouple
is the one that has an output when no bias is present….

Take a 10K thermistor and a 10K resistor and put them in series.  You will get 
roughly Vcc / 2 at 25C
at the junction of the two parts.. The output will change about 1.5% per 
degree. With a 5V Vcc, that’s 
around 38 mV/C. 

Bob

> On Jun 4, 2017, at 4:49 PM, Donald E. Pauly  wrote:
> 
> I own several Fluke 52 stereo thermometers with K themocouples.  They
> run 40 μV/C°.  All thermistors have tiny outputs without op amps.
> They also suffer from self heating.  AD590 sensors give AT LEAST 15
> mV/C° without op amps.  If a regulated 3,000V supply is available they
> can give 2 V/C° into a 1 Watt 10 Meg resistor.
> 
> πθ°μΩω±√·Γλ
> WB0KVV
> 
> 
> -- Forwarded message --
> From: Bob kb8tq 
> Date: Sun, Jun 4, 2017 at 11:46 AM
> Subject: Re: [time-nuts] HP5061B Versus HP5071 Cesium Line Frequencies
> To: Discussion of precise time and frequency measurement 
> Cc: "rwa...@aol.com" , "Donald E. Pauly"
> 
> 
> 
> Hi
> 
> I think you have thermistors and thermocouples a bit mixed up. You can get
> quite substantial output voltages from a thermistor bridge….
> 
> Bob
> 
>> On Jun 4, 2017, at 11:44 AM, 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.
>> 
>> Where did you get the idea to use a 1 k load for an AD590?  If you run
>> it from a -5 V supply you can use a 15 k load to a +5V supply.  This
>> gives 15 V/C° output.  If you drive it from a 10 Meg impedance current
>> source, you get 30,000 V/ C°.  If I remember correctly, I drove a
>> power MOSFET heater gate directly in my prototype oven 20 years ago.
>> It would go from full off to full on in 1/15 ° C.  Noise is 1/25,000 °
>> C in a 1 cycle bandwidth.
>> 
>> The room temperature coefficient of an AT crystal is -100 ppb per
>> reference cut angle in minutes.  (-600 ppb/C° for standard crystal)
>> The practical limit in a crystal designed for room temperature is
>> about 0.1' cut accuracy or ±10 ppb/C°.  If you have access to an
>> atomic standard, you can use feed forward to get ±1 ppb/C°.  If the
>> temperature can be held to ±0.001° C, this is ±1 part per trillion.
>> This kind of accuracy has never been heard of.  Feed forward also
>> allows you to incorporate the components of the oscillator into the
>> thermal behavior.  It does no good to have a perfect crystal if the
>> oscillator components drift.
>> 
>> πθ°μΩω±√·Γλ
>> WB0KVV
>> 
>> -- Forwarded message --
>> From: jimlux 
>> Date: Sun, Jun 4, 2017 at 4:47 AM
>> Subject: Re: [time-nuts] Fwd: HP5061B Versus HP5071 Cesium Line Frequencies
>> To: time-nuts@febo.com
>> 
>> 
>> On 6/3/17 9:56 PM, Donald E. Pauly wrote:
>> 
>>> It was only in the early 70s that Analog Devices invented the AD590
>>> solid state temperature sensor.  It made thermister bridges obsolete.
>> 
>> 
>> There is a difference between something like a platinum resistance
>> thermometer (PRT or RTD) and a thermistor, but they both are "measure
>> resistance to measure temperature" devices.
>> 
>> Yes, the AD590 is a useful part (I've got some in a device being
>> launched in August), but PRTs,thermistors, and thermocouples are still
>> widely used.
>> 
>> I don't know that the inherent precision (at room temperature)of the
>> various techniques is wildly different.  A 1mV/K signal (AD590 into a
>> 1k resistor) has to be measured to 0.1mV for 0.1 degree accuracy.
>> That's out of 300mV, so 1 part in 3000
>> 
>> A type E thermocouple is 1.495 mV at 25C and 1.801 at 30C, so about
>> 0.06 mV/K slope. Measure 0.006mV for 0.1 degree  (plus the "cold
>> junction" issue).  1 part in 250 measurement.
>> 
>> Modern RTDs all are 0.00385 ohm/ohm/degree at 25C.  Typically, you
>> have a 100 ohm device (although there are Pt1000s), so it's changing
>> 0.385 ohm/degree.  1 part in 3000
>> 
>> Checking the Omega catalog.. A 44007 has nominal 5k at 25C, and is
>> 4787 at 26C, so 1 part in 24.
>> 
>> Especially these days, with computers to deal with nonlinear
>> calibration curves, there's an awful lot of TCs and Thermistors in
>> use. The big advantage of the AD590 and PRT is that they are basically
>> linear over a convenient temperature range.
>> 
>> In a variety applications, other aspects of the measurement device are
>> important - ESD sensitivity, tolerance to wildly out of spec
>> temperature without damage, radiation effects etc.  Not an issue here,
>> but I'll note that the 

Re: [time-nuts] HP5061B Versus HP5071 Cesium Line Frequencies

[jimlux]

On 6/4/17 1:49 PM, Donald E. Pauly wrote:

I own several Fluke 52 stereo thermometers with K themocouples.  They
run 40 μV/C°.  All thermistors have tiny outputs without op amps.
They also suffer from self heating.  AD590 sensors give AT LEAST 15
mV/C° without op amps.  If a regulated 3,000V supply is available they
can give 2 V/C° into a 1 Watt 10 Meg resistor.


3kV?

That's an interesting concept. Better make sure you set your resistors 
up right and keep your temperature range limited, since the max voltage 
across the device is 30V.  And the power supply ripple had better be 
less than 1V (PSRR is 0.1 uA/V at 15V, and 0.5 uA/V at 5V).


What's the tempco of that resistor?

And, you know that the calibration error is +/- 0.5 degree (for the 
better M grade).. Yeah, it's repeatable to 0.1 degree (0.1 uA).







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[time-nuts] TAPR GPS Experimenters Kit

[Donald E. Pauly]

We are finishing a pair of HP5061B cesium standards which we have up
and running.  We would like to acquire a GPS disciplined oscillator
with 5 or 10 mc output for comparison with the cesium clocks.  1 pulse
per second would be nice but is not mandatory.  A roof antenna with
preamp that could drive 100 feet or so of foam RG-58 is required.
Does anyone have such a device that needs a new home?  If not, what
should we look for on eBay?

πθ°μΩω±√·Γλ
WB0KVV

-- Forwarded message --
From: Dave Mallery 
Date: Sun, Jun 4, 2017 at 8:54 AM
Subject: Re: [time-nuts] TAPR GPS Experimenters Kit
To: Discussion of precise time and frequency measurement 


hi

I have been having great results with my M12 and Lady H.  I (foolish me)
had tried to cobble up a Perl program at first...  just browse through some
of the 400+ pages of heathgps.cpp to see why that was a bad idea!  Both my
M12 and my Tbolt are controlled by Heather running on two PI3s.

Now, i would like to get a Lucent RFTG-u REV-0 to run using the PPS from
the M12.  there is a nice PPS interrupt driven arduino sketch on the Sync
Channel Blog.  I'd love to hear from anyone who is also trying this.

73

dave mallery, k5en


On Sun, Jun 4, 2017 at 7:03 AM, Gregory Beat  wrote:

> Mark -
> Yes, it does. :-)
> The "S" and "!" menus are the most frequent menus I use with LH.
>
> Jerry is using SynTAC.
> After a few e-mail exchanges, off-list, problem was antenna location.
>
> gb
> ===
> So does Lady Heather... the "S" menu control things like self-surveys,
> entering fixed position coordinates,  and the receiver operating mode.  SN
> will put it in Navigation (3D) mode.  SH will put it in position Hold mode
> (timing mode).
>
> Sent from iPad Air
> ___
> 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.
>



--
Dave Mallery, K5EN (ubuntu linux 16-10)
PO Box 15  Ophir,  OR  97464

  linux counter #64628 (since 1997)
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[time-nuts] HP5061B Versus HP5071 Cesium Line Frequencies

[Donald E. Pauly]

I own several Fluke 52 stereo thermometers with K themocouples.  They
run 40 μV/C°.  All thermistors have tiny outputs without op amps.
They also suffer from self heating.  AD590 sensors give AT LEAST 15
mV/C° without op amps.  If a regulated 3,000V supply is available they
can give 2 V/C° into a 1 Watt 10 Meg resistor.

πθ°μΩω±√·Γλ
WB0KVV


-- Forwarded message --
From: Bob kb8tq 
Date: Sun, Jun 4, 2017 at 11:46 AM
Subject: Re: [time-nuts] HP5061B Versus HP5071 Cesium Line Frequencies
To: Discussion of precise time and frequency measurement 
Cc: "rwa...@aol.com" , "Donald E. Pauly"



Hi

I think you have thermistors and thermocouples a bit mixed up. You can get
quite substantial output voltages from a thermistor bridge….

Bob

> On Jun 4, 2017, at 11:44 AM, 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.
>
> Where did you get the idea to use a 1 k load for an AD590?  If you run
> it from a -5 V supply you can use a 15 k load to a +5V supply.  This
> gives 15 V/C° output.  If you drive it from a 10 Meg impedance current
> source, you get 30,000 V/ C°.  If I remember correctly, I drove a
> power MOSFET heater gate directly in my prototype oven 20 years ago.
> It would go from full off to full on in 1/15 ° C.  Noise is 1/25,000 °
> C in a 1 cycle bandwidth.
>
> The room temperature coefficient of an AT crystal is -100 ppb per
> reference cut angle in minutes.  (-600 ppb/C° for standard crystal)
> The practical limit in a crystal designed for room temperature is
> about 0.1' cut accuracy or ±10 ppb/C°.  If you have access to an
> atomic standard, you can use feed forward to get ±1 ppb/C°.  If the
> temperature can be held to ±0.001° C, this is ±1 part per trillion.
> This kind of accuracy has never been heard of.  Feed forward also
> allows you to incorporate the components of the oscillator into the
> thermal behavior.  It does no good to have a perfect crystal if the
> oscillator components drift.
>
> πθ°μΩω±√·Γλ
> WB0KVV
>
> -- Forwarded message --
> From: jimlux 
> Date: Sun, Jun 4, 2017 at 4:47 AM
> Subject: Re: [time-nuts] Fwd: HP5061B Versus HP5071 Cesium Line Frequencies
> To: time-nuts@febo.com
>
>
> On 6/3/17 9:56 PM, Donald E. Pauly wrote:
>
>> It was only in the early 70s that Analog Devices invented the AD590
>> solid state temperature sensor.  It made thermister bridges obsolete.
>
>
> There is a difference between something like a platinum resistance
> thermometer (PRT or RTD) and a thermistor, but they both are "measure
> resistance to measure temperature" devices.
>
> Yes, the AD590 is a useful part (I've got some in a device being
> launched in August), but PRTs,thermistors, and thermocouples are still
> widely used.
>
> I don't know that the inherent precision (at room temperature)of the
> various techniques is wildly different.  A 1mV/K signal (AD590 into a
> 1k resistor) has to be measured to 0.1mV for 0.1 degree accuracy.
> That's out of 300mV, so 1 part in 3000
>
> A type E thermocouple is 1.495 mV at 25C and 1.801 at 30C, so about
> 0.06 mV/K slope. Measure 0.006mV for 0.1 degree  (plus the "cold
> junction" issue).  1 part in 250 measurement.
>
> Modern RTDs all are 0.00385 ohm/ohm/degree at 25C.  Typically, you
> have a 100 ohm device (although there are Pt1000s), so it's changing
> 0.385 ohm/degree.  1 part in 3000
>
> Checking the Omega catalog.. A 44007 has nominal 5k at 25C, and is
> 4787 at 26C, so 1 part in 24.
>
> Especially these days, with computers to deal with nonlinear
> calibration curves, there's an awful lot of TCs and Thermistors in
> use. The big advantage of the AD590 and PRT is that they are basically
> linear over a convenient temperature range.
>
> In a variety applications, other aspects of the measurement device are
> important - ESD sensitivity, tolerance to wildly out of spec
> temperature without damage, radiation effects etc.  Not an issue here,
> but I'll note that the thermistor, PRT, and thermocouple are
> essentially ESD immune. The AD590 most certainly is not.
>
> If you go out and buy cheap industrial PID temperature controller it
> will have input modes for various thermocouples and PRTs.  I suppose
> there's probably some that take 1uA/K, but it's not something I would
> expect.
>
> So I wouldn't say thermistor bridges (or other temperature
> measurements) are obsolete.
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> and follow the 

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

[Chris Albertson]

Look at the temperature coefficient of your XO.  Then figure a very simply
control loop and a thermistor will keep a block of aluminum within 0.1C of
a set point.  Use a decent size block and insulation

We drilled a deep hole then epoxied the thermistor.  I think this step is
important as you want to measure the center of the black, not the surface..
   Then epoxied a TEC (aka Peltier device) to the Al Block.  TECs are nice
because they can both cool and heat.   On the other side other TEC was a
rather large heat sink (or heat source depending on the polarity) a uP and
a PID loop controlled the output current.   Place an insulator over the
controlled end of the block.   I think a stainless steel vacuum insulated
coffee mug works well.

I think cheap thermistors are OK as they will never, in use, see
temperature swings of more then 0.1C so who care if they are linear or not.
They are all linear enough over a short range.  What you pay for is being
perfect over a 100C range, you don't need that.


We used the pelter because we preferred a cool "oven" to a hot one.   The
theory has that we get less electronic noise so we ran the TEC in cooling
mode.   But for your use a resistive heater would be cheaper.   But in
either case you see a coffee mug with a round chunk of Al shoved in and
heat sink fins showing.

When I was doing some contraction work, I thought of it would be fun to
toss an XO in the big hole that was going to get a truckload of concrete
poured into it.  The temperature down there would be very stable.



On Sun, Jun 4, 2017 at 5:13 AM, jimlux  wrote:

> I recall some years ago folks were talking about putting a PTC thermistor
> on the TCXO of a FlexRadio SDR1000 to stabilize the frequency as a sort of
> poor-man's OCXO.
> It's also referenced at
> http://www.setileague.org/askdr/xtaloven.htm
> where he says "order of magnitude improvement" with no numbers (from 1% to
> 0.1% or from 1 ppb to 0.1 ppb?)
>
> I wonder how well that actually works.
>
> Say you bought an inexpensive (perhaps non TC) XO and an equally
> inexpensive thermistor, glued on on the other, hooked em both up to 3.3 or
> 5V.
>
> Yeah, there's issues with room air blowing on it, and tolerances in both
> the XO and thermistor, so your absolute frequency accuracy may not be so
> hot. But what sort of medium to long term performance can one expect.
>
> I did some searches, because I'm sure we've discussed this before, but I
> couldn't find it.  There was some stuff from Oct 2007, but that was in the
> context of a more complex circuit, and the thermistor was the sensor.
> (discussions of TE devices too)
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>



-- 

Chris Albertson
Redondo Beach, California
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[time-nuts] HP 3048 NI GP-IB cards help requested

[Richard (Rick) Karlquist]

I am trying to set up an HP 3048 system and
have read the KE5FX web page on the software.
I have successfully installed both PN3048 and
the HT Basic port of RMB.  The programs basically
appear to run correctly on my Windows 7 desktop.

HOWEVER, I don't have a GP-IB card.  According to
KE5FX, both the bus card and USB dongle types work.
It looks like current NI driver supports many
legacy cards.  I am curious about whether this
means that all of these cards will be OK, or if I
have to buy the latest card/dongle?  I would like
to be able to run both programs.  The HT Basic
site says that certain bus chips are incompatible
with its software, and I should call them for suggestions.

I would appreciate hearing from anyone who can vouch
for a compatible NI card/dongle, either current production
or a legacy one.  (If someone has one they want to
sell, let me know).  Ideally I would like to use the
same card/dongle for both the PN3048 and the HTBasic
programs.  In the PN3048 program, there is
a menu pick to select NI card of type 1 or type 2.
Does anyone know anything about that?

Rick N6RK


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Re: [time-nuts] HP5061B Versus HP5071 Cesium Line Frequencies

[Bob kb8tq]

Hi

I think you have thermistors and thermocouples a bit mixed up. You can get
quite substantial output voltages from a thermistor bridge….

Bob

> On Jun 4, 2017, at 11:44 AM, 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.
> 
> Where did you get the idea to use a 1 k load for an AD590?  If you run
> it from a -5 V supply you can use a 15 k load to a +5V supply.  This
> gives 15 V/C° output.  If you drive it from a 10 Meg impedance current
> source, you get 30,000 V/ C°.  If I remember correctly, I drove a
> power MOSFET heater gate directly in my prototype oven 20 years ago.
> It would go from full off to full on in 1/15 ° C.  Noise is 1/25,000 °
> C in a 1 cycle bandwidth.
> 
> The room temperature coefficient of an AT crystal is -100 ppb per
> reference cut angle in minutes.  (-600 ppb/C° for standard crystal)
> The practical limit in a crystal designed for room temperature is
> about 0.1' cut accuracy or ±10 ppb/C°.  If you have access to an
> atomic standard, you can use feed forward to get ±1 ppb/C°.  If the
> temperature can be held to ±0.001° C, this is ±1 part per trillion.
> This kind of accuracy has never been heard of.  Feed forward also
> allows you to incorporate the components of the oscillator into the
> thermal behavior.  It does no good to have a perfect crystal if the
> oscillator components drift.
> 
> πθ°μΩω±√·Γλ
> WB0KVV
> 
> -- Forwarded message --
> From: jimlux 
> Date: Sun, Jun 4, 2017 at 4:47 AM
> Subject: Re: [time-nuts] Fwd: HP5061B Versus HP5071 Cesium Line Frequencies
> To: time-nuts@febo.com
> 
> 
> On 6/3/17 9:56 PM, Donald E. Pauly wrote:
> 
>> It was only in the early 70s that Analog Devices invented the AD590
>> solid state temperature sensor.  It made thermister bridges obsolete.
> 
> 
> There is a difference between something like a platinum resistance
> thermometer (PRT or RTD) and a thermistor, but they both are "measure
> resistance to measure temperature" devices.
> 
> Yes, the AD590 is a useful part (I've got some in a device being
> launched in August), but PRTs,thermistors, and thermocouples are still
> widely used.
> 
> I don't know that the inherent precision (at room temperature)of the
> various techniques is wildly different.  A 1mV/K signal (AD590 into a
> 1k resistor) has to be measured to 0.1mV for 0.1 degree accuracy.
> That's out of 300mV, so 1 part in 3000
> 
> A type E thermocouple is 1.495 mV at 25C and 1.801 at 30C, so about
> 0.06 mV/K slope. Measure 0.006mV for 0.1 degree  (plus the "cold
> junction" issue).  1 part in 250 measurement.
> 
> Modern RTDs all are 0.00385 ohm/ohm/degree at 25C.  Typically, you
> have a 100 ohm device (although there are Pt1000s), so it's changing
> 0.385 ohm/degree.  1 part in 3000
> 
> Checking the Omega catalog.. A 44007 has nominal 5k at 25C, and is
> 4787 at 26C, so 1 part in 24.
> 
> Especially these days, with computers to deal with nonlinear
> calibration curves, there's an awful lot of TCs and Thermistors in
> use. The big advantage of the AD590 and PRT is that they are basically
> linear over a convenient temperature range.
> 
> In a variety applications, other aspects of the measurement device are
> important - ESD sensitivity, tolerance to wildly out of spec
> temperature without damage, radiation effects etc.  Not an issue here,
> but I'll note that the thermistor, PRT, and thermocouple are
> essentially ESD immune. The AD590 most certainly is not.
> 
> If you go out and buy cheap industrial PID temperature controller it
> will have input modes for various thermocouples and PRTs.  I suppose
> there's probably some that take 1uA/K, but it's not something I would
> expect.
> 
> So I wouldn't say thermistor bridges (or other temperature
> measurements) are obsolete.
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Re: [time-nuts] HP5061B Versus HP5071 Cesium Line Frequencies

[Bob kb8tq]

Hi

Ok, when you wrote the specification for your crystals what was the tolerance 
on the angle
for those crystals? What did the suppliers who quoted to your spec say about 
the angle tolerance 
you specified? When they shipped against your volume requirements how did they 
do against the 
specification? When your incoming QA tested the crystals what did they find? 
When you put the 
crystals into production oscillators and tested the result how did they 
perform? 

Bob


> On Jun 4, 2017, at 11:09 AM, Donald E. Pauly  wrote:
> 
> I've bought dozens of them over the years and talked to crystal
> engineers for tens of hours.  I watched them plated and tuned at a
> crystal filter company in Phoenix.  I own Virgil Bottom's book on the
> subject and understood half of it.
> 
> πθ°μΩω±√·Γλ
> WB0KVV
> 
> 
> -- Forwarded message --
> From: Bob kb8tq 
> Date: Sun, Jun 4, 2017 at 5:15 AM
> Subject: Re: [time-nuts] HP5061B Versus HP5071 Cesium Line Frequencies
> To: Discussion of precise time and frequency measurement 
> Cc: "rwa...@aol.com" , "Donald E. Pauly"
> 
> 
> 
> Hi
> 
> Have you ever tried to actually *buy* a crystal built to a
> specification? There is a
> tolerance on them. That has a profound impact on what you can *buy*.
> 
> Bob
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[time-nuts] Fwd: Fwd: HP5061B Versus HP5071 Cesium Line Frequencies

[Donald E. Pauly]

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.

Where did you get the idea to use a 1 k load for an AD590?  If you run
it from a -5 V supply you can use a 15 k load to a +5V supply.  This
gives 15 V/C° output.  If you drive it from a 10 Meg impedance current
source, you get 30,000 V/ C°.  If I remember correctly, I drove a
power MOSFET heater gate directly in my prototype oven 20 years ago.
It would go from full off to full on in 1/15 ° C.  Noise is 1/25,000 °
C in a 1 cycle bandwidth.

The room temperature coefficient of an AT crystal is -100 ppb per
reference cut angle in minutes.  (-600 ppb/C° for standard crystal)
The practical limit in a crystal designed for room temperature is
about 0.1' cut accuracy or ±10 ppb/C°.  If you have access to an
atomic standard, you can use feed forward to get ±1 ppb/C°.  If the
temperature can be held to ±0.001° C, this is ±1 part per trillion.
This kind of accuracy has never been heard of.  Feed forward also
allows you to incorporate the components of the oscillator into the
thermal behavior.  It does no good to have a perfect crystal if the
oscillator components drift.

πθ°μΩω±√·Γλ
WB0KVV

-- Forwarded message --
From: jimlux 
Date: Sun, Jun 4, 2017 at 4:47 AM
Subject: Re: [time-nuts] Fwd: HP5061B Versus HP5071 Cesium Line Frequencies
To: time-nuts@febo.com


On 6/3/17 9:56 PM, Donald E. Pauly wrote:

> It was only in the early 70s that Analog Devices invented the AD590
> solid state temperature sensor.  It made thermister bridges obsolete.


There is a difference between something like a platinum resistance
thermometer (PRT or RTD) and a thermistor, but they both are "measure
resistance to measure temperature" devices.

Yes, the AD590 is a useful part (I've got some in a device being
launched in August), but PRTs,thermistors, and thermocouples are still
widely used.

I don't know that the inherent precision (at room temperature)of the
various techniques is wildly different.  A 1mV/K signal (AD590 into a
1k resistor) has to be measured to 0.1mV for 0.1 degree accuracy.
That's out of 300mV, so 1 part in 3000

A type E thermocouple is 1.495 mV at 25C and 1.801 at 30C, so about
0.06 mV/K slope. Measure 0.006mV for 0.1 degree  (plus the "cold
junction" issue).  1 part in 250 measurement.

Modern RTDs all are 0.00385 ohm/ohm/degree at 25C.  Typically, you
have a 100 ohm device (although there are Pt1000s), so it's changing
0.385 ohm/degree.  1 part in 3000

Checking the Omega catalog.. A 44007 has nominal 5k at 25C, and is
4787 at 26C, so 1 part in 24.

Especially these days, with computers to deal with nonlinear
calibration curves, there's an awful lot of TCs and Thermistors in
use. The big advantage of the AD590 and PRT is that they are basically
linear over a convenient temperature range.

In a variety applications, other aspects of the measurement device are
important - ESD sensitivity, tolerance to wildly out of spec
temperature without damage, radiation effects etc.  Not an issue here,
but I'll note that the thermistor, PRT, and thermocouple are
essentially ESD immune. The AD590 most certainly is not.

If you go out and buy cheap industrial PID temperature controller it
will have input modes for various thermocouples and PRTs.  I suppose
there's probably some that take 1uA/K, but it's not something I would
expect.

So I wouldn't say thermistor bridges (or other temperature
measurements) are obsolete.
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[time-nuts] Fwd: HP5061B Versus HP5071 Cesium Line Frequencies

[Donald E. Pauly]

I've bought dozens of them over the years and talked to crystal
engineers for tens of hours.  I watched them plated and tuned at a
crystal filter company in Phoenix.  I own Virgil Bottom's book on the
subject and understood half of it.

πθ°μΩω±√·Γλ
WB0KVV


-- Forwarded message --
From: Bob kb8tq 
Date: Sun, Jun 4, 2017 at 5:15 AM
Subject: Re: [time-nuts] HP5061B Versus HP5071 Cesium Line Frequencies
To: Discussion of precise time and frequency measurement 
Cc: "rwa...@aol.com" , "Donald E. Pauly"



Hi

Have you ever tried to actually *buy* a crystal built to a
specification? There is a
tolerance on them. That has a profound impact on what you can *buy*.

Bob
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Re: [time-nuts] poor-man's oven

[R. Kuehn]

Maybe you want to check out the work of Hans Summers he has done some
impressive low cost stuff:
http://www.hanssummers.com/ocxosynth.html
http://www.qrp-labs.com/ocxokit.html

Ralph

On Sun, Jun 4, 2017 at 07:19 jimlux  wrote:

> I recall some years ago folks were talking about putting a PTC
> thermistor on the TCXO of a FlexRadio SDR1000 to stabilize the frequency
> as a sort of poor-man's OCXO.
> It's also referenced at
> http://www.setileague.org/askdr/xtaloven.htm
> where he says "order of magnitude improvement" with no numbers (from 1%
> to 0.1% or from 1 ppb to 0.1 ppb?)
>
> I wonder how well that actually works.
>
> Say you bought an inexpensive (perhaps non TC) XO and an equally
> inexpensive thermistor, glued on on the other, hooked em both up to 3.3
> or 5V.
>
> Yeah, there's issues with room air blowing on it, and tolerances in both
> the XO and thermistor, so your absolute frequency accuracy may not be so
> hot. But what sort of medium to long term performance can one expect.
>
> I did some searches, because I'm sure we've discussed this before, but I
> couldn't find it.  There was some stuff from Oct 2007, but that was in
> the context of a more complex circuit, and the thermistor was the
> sensor. (discussions of TE devices too)
> ___
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Re: [time-nuts] TAPR GPS Experimenters Kit

[Dave Mallery]

hi

I have been having great results with my M12 and Lady H.  I (foolish me)
had tried to cobble up a Perl program at first...  just browse through some
of the 400+ pages of heathgps.cpp to see why that was a bad idea!  Both my
M12 and my Tbolt are controlled by Heather running on two PI3s.

Now, i would like to get a Lucent RFTG-u REV-0 to run using the PPS from
the M12.  there is a nice PPS interrupt driven arduino sketch on the Sync
Channel Blog.  I'd love to hear from anyone who is also trying this.

73

dave mallery, k5en


On Sun, Jun 4, 2017 at 7:03 AM, Gregory Beat  wrote:

> Mark -
> Yes, it does. :-)
> The "S" and "!" menus are the most frequent menus I use with LH.
>
> Jerry is using SynTAC.
> After a few e-mail exchanges, off-list, problem was antenna location.
>
> gb
> ===
> So does Lady Heather... the "S" menu control things like self-surveys,
> entering fixed position coordinates,  and the receiver operating mode.  SN
> will put it in Navigation (3D) mode.  SH will put it in position Hold mode
> (timing mode).
>
> Sent from iPad Air
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> and follow the instructions there.
>



-- 
Dave Mallery, K5EN (ubuntu linux 16-10)
PO Box 15  Ophir,  OR  97464

  linux counter #64628 (since 1997)
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Re: [time-nuts] poor-man's oven

[Bob kb8tq]

Hi

If you have not done so already, you might try bumping the temperature a bit to 
search for the 
upper turn in the crystal curve. Based on the data in the plots, you do have an 
AT that is cut 
with an upper turn. 

Bob

> On Jun 4, 2017, at 11:30 AM, Dan Rae  wrote:
> 
> 

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

[Dan Rae]

The attached plot shows the sort of improvement in warm up time and 
stability of a simple "oven" made by attaching a Darlington heater 
transistor and thermistor to a Crystek 100 MHz oscillator, adjusted to 
set the osc temp to around 35C and wrapping it all in foam.  In this 
application, a DDS clock for an HF transceiver, the result was well 
worthwhile.


Dan - ac6ao




Crystek Test.doc
Description: MS-Word document
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Re: [time-nuts] poor-man's oven

[Bob kb8tq]

Hi

There is no way to know how every outfit makes their products. My guess is that
the temperature compensation “stuff” is pretty stable. At least it has been on 
all 
the product I’ve designed :) I’d bet that the crystals in the TCXO’s are the 
culprit. 
In some of the factories I’ve visited, they package their own crystals. They 
bring in the
blanks pre-sorted and take it from there. The aging pretty much all comes from 
the
plating / packaging process. It would not surprise me to find that long term 
aging is 
not a major focus on parts headed for sort lifespan consumer electronics ...

Bob

> On Jun 4, 2017, at 9:45 AM, Tim Shoppa  wrote:
> 
> Bob, at the same time, look at all the guys here who absolutely insist that
> the only way to use a double-oven OCXO is to put it in a tightly
> temperature controlled environment. "Nuts", yes, but that's why we're here!
> 
> I myself have been extremely disappointed with the aging characteristics of
> low-end TCXO's. They seem to age even worse than plain old crystal
> oscillators, My theory, is this is because the temperature compensation
> components are themselves aging more than an AT cut crystal does by itself,
> but I've never ripped into one (they're way too tiny to rip into anyway!).
> 
> Tim N3QE
> 
> On Sun, Jun 4, 2017 at 9:36 AM, Bob kb8tq  wrote:
> 
>> Hi
>> 
>> The gotcha is that you have multiple systems working against each other.
>> The crystal in the TCXO has
>> one temperature characteristic. The compensation in the TCXO has a
>> temperature characteristic. They
>> cancel each other out to a limited degree. The residual slope may (or may
>> not) be as shallow as you
>> might think. Your PTC is at an arbitrary point on the residual curve. A
>> somewhat more subtle issue is
>> the gradient between your PTC, the crystal, and the compensation as it
>> cycles.
>> 
>> If the TCXO really isn’t a full TCXO, then some of this goes away. A +/- 2
>> ppm 0-50C “TCXO" may not have
>> any compensation in it at all. Some 0 to 70C parts are done as 2 ppm 0 to
>> 50 and only compensated at the
>> hot end. They actually may be worse with the PTC than at room...
>> 
>> Yes this all assumes an AT cut in the TCXO. That’s a pretty good bet ….
>> 
>> Bob
>> 
>> 
>>> On Jun 4, 2017, at 8:13 AM, jimlux  wrote:
>>> 
>>> I recall some years ago folks were talking about putting a PTC
>> thermistor on the TCXO of a FlexRadio SDR1000 to stabilize the frequency as
>> a sort of poor-man's OCXO.
>>> It's also referenced at
>>> http://www.setileague.org/askdr/xtaloven.htm
>>> where he says "order of magnitude improvement" with no numbers (from 1%
>> to 0.1% or from 1 ppb to 0.1 ppb?)
>>> 
>>> I wonder how well that actually works.
>>> 
>>> Say you bought an inexpensive (perhaps non TC) XO and an equally
>> inexpensive thermistor, glued on on the other, hooked em both up to 3.3 or
>> 5V.
>>> 
>>> Yeah, there's issues with room air blowing on it, and tolerances in both
>> the XO and thermistor, so your absolute frequency accuracy may not be so
>> hot. But what sort of medium to long term performance can one expect.
>>> 
>>> I did some searches, because I'm sure we've discussed this before, but I
>> couldn't find it.  There was some stuff from Oct 2007, but that was in the
>> context of a more complex circuit, and the thermistor was the sensor.
>> (discussions of TE devices too)
>>> ___
>>> 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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Re: [time-nuts] TAPR GPS Experimenters Kit

[Gregory Beat]

Mark -
Yes, it does. :-)
The "S" and "!" menus are the most frequent menus I use with LH.

Jerry is using SynTAC.
After a few e-mail exchanges, off-list, problem was antenna location.

gb
===
So does Lady Heather... the "S" menu control things like self-surveys, entering 
fixed position coordinates,  and the receiver operating mode.  SN will put it 
in Navigation (3D) mode.  SH will put it in position Hold mode (timing mode).  

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

[Tim Shoppa]

Bob, at the same time, look at all the guys here who absolutely insist that
the only way to use a double-oven OCXO is to put it in a tightly
temperature controlled environment. "Nuts", yes, but that's why we're here!

I myself have been extremely disappointed with the aging characteristics of
low-end TCXO's. They seem to age even worse than plain old crystal
oscillators, My theory, is this is because the temperature compensation
components are themselves aging more than an AT cut crystal does by itself,
but I've never ripped into one (they're way too tiny to rip into anyway!).

Tim N3QE

On Sun, Jun 4, 2017 at 9:36 AM, Bob kb8tq  wrote:

> Hi
>
> The gotcha is that you have multiple systems working against each other.
> The crystal in the TCXO has
> one temperature characteristic. The compensation in the TCXO has a
> temperature characteristic. They
> cancel each other out to a limited degree. The residual slope may (or may
> not) be as shallow as you
> might think. Your PTC is at an arbitrary point on the residual curve. A
> somewhat more subtle issue is
> the gradient between your PTC, the crystal, and the compensation as it
> cycles.
>
> If the TCXO really isn’t a full TCXO, then some of this goes away. A +/- 2
> ppm 0-50C “TCXO" may not have
> any compensation in it at all. Some 0 to 70C parts are done as 2 ppm 0 to
> 50 and only compensated at the
> hot end. They actually may be worse with the PTC than at room...
>
> Yes this all assumes an AT cut in the TCXO. That’s a pretty good bet ….
>
> Bob
>
>
> > On Jun 4, 2017, at 8:13 AM, jimlux  wrote:
> >
> > I recall some years ago folks were talking about putting a PTC
> thermistor on the TCXO of a FlexRadio SDR1000 to stabilize the frequency as
> a sort of poor-man's OCXO.
> > It's also referenced at
> > http://www.setileague.org/askdr/xtaloven.htm
> > where he says "order of magnitude improvement" with no numbers (from 1%
> to 0.1% or from 1 ppb to 0.1 ppb?)
> >
> > I wonder how well that actually works.
> >
> > Say you bought an inexpensive (perhaps non TC) XO and an equally
> inexpensive thermistor, glued on on the other, hooked em both up to 3.3 or
> 5V.
> >
> > Yeah, there's issues with room air blowing on it, and tolerances in both
> the XO and thermistor, so your absolute frequency accuracy may not be so
> hot. But what sort of medium to long term performance can one expect.
> >
> > I did some searches, because I'm sure we've discussed this before, but I
> couldn't find it.  There was some stuff from Oct 2007, but that was in the
> context of a more complex circuit, and the thermistor was the sensor.
> (discussions of TE devices too)
> > ___
> > time-nuts mailing list -- time-nuts@febo.com
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> mailman/listinfo/time-nuts
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Re: [time-nuts] poor-man's oven

[Bob kb8tq]

Hi

The gotcha is that you have multiple systems working against each other. The 
crystal in the TCXO has
one temperature characteristic. The compensation in the TCXO has a temperature 
characteristic. They
cancel each other out to a limited degree. The residual slope may (or may not) 
be as shallow as you
might think. Your PTC is at an arbitrary point on the residual curve. A 
somewhat more subtle issue is 
the gradient between your PTC, the crystal, and the compensation as it cycles. 

If the TCXO really isn’t a full TCXO, then some of this goes away. A +/- 2 ppm 
0-50C “TCXO" may not have
any compensation in it at all. Some 0 to 70C parts are done as 2 ppm 0 to 50 
and only compensated at the 
hot end. They actually may be worse with the PTC than at room...

Yes this all assumes an AT cut in the TCXO. That’s a pretty good bet ….

Bob


> On Jun 4, 2017, at 8:13 AM, jimlux  wrote:
> 
> I recall some years ago folks were talking about putting a PTC thermistor on 
> the TCXO of a FlexRadio SDR1000 to stabilize the frequency as a sort of 
> poor-man's OCXO.
> It's also referenced at
> http://www.setileague.org/askdr/xtaloven.htm
> where he says "order of magnitude improvement" with no numbers (from 1% to 
> 0.1% or from 1 ppb to 0.1 ppb?)
> 
> I wonder how well that actually works.
> 
> Say you bought an inexpensive (perhaps non TC) XO and an equally inexpensive 
> thermistor, glued on on the other, hooked em both up to 3.3 or 5V.
> 
> Yeah, there's issues with room air blowing on it, and tolerances in both the 
> XO and thermistor, so your absolute frequency accuracy may not be so hot. But 
> what sort of medium to long term performance can one expect.
> 
> I did some searches, because I'm sure we've discussed this before, but I 
> couldn't find it.  There was some stuff from Oct 2007, but that was in the 
> context of a more complex circuit, and the thermistor was the sensor. 
> (discussions of TE devices too)
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Re: [time-nuts] poor-man's oven

[Mike Naruta AA8K]

My SDR-1000 showed substantially less "WWV drift" after adding 
the PTC thermistor to the TCXO.  Sorry, no measurements because 
that was before I had a GPSDO.


Mikr - AA8K


On 06/04/2017 08:13 AM, jimlux wrote:
I recall some years ago folks were talking about putting a PTC 
thermistor on the TCXO of a FlexRadio SDR1000 to stabilize the 
frequency as a sort of poor-man's OCXO.

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

[John Ackermann N8UR]

We did this years ago on a 430 MHz data radio with an utterly uncompensated 
crystal that would drift through the passband.  After building our own for a 
while, we discovered that Yaesu had something even better available through 
their replacement parts shop -- a spring clip with PTC that snapped tightly 
over the crystal case.  I never did any formal measurements, but it did improve 
stability quite a bit for radios that were sitting in uncontrolled environments.

John

On Jun 4, 2017, 8:18 AM, at 8:18 AM, jimlux  wrote:
>I recall some years ago folks were talking about putting a PTC 
>thermistor on the TCXO of a FlexRadio SDR1000 to stabilize the
>frequency 
>as a sort of poor-man's OCXO.
>It's also referenced at
>http://www.setileague.org/askdr/xtaloven.htm
>where he says "order of magnitude improvement" with no numbers (from 1%
>
>to 0.1% or from 1 ppb to 0.1 ppb?)
>
>I wonder how well that actually works.
>
>Say you bought an inexpensive (perhaps non TC) XO and an equally 
>inexpensive thermistor, glued on on the other, hooked em both up to 3.3
>
>or 5V.
>
>Yeah, there's issues with room air blowing on it, and tolerances in
>both 
>the XO and thermistor, so your absolute frequency accuracy may not be
>so 
>hot. But what sort of medium to long term performance can one expect.
>
>I did some searches, because I'm sure we've discussed this before, but
>I 
>couldn't find it.  There was some stuff from Oct 2007, but that was in 
>the context of a more complex circuit, and the thermistor was the 
>sensor. (discussions of TE devices too)
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Re: [time-nuts] HP5061B Versus HP5071 Cesium Line Frequencies

[Bob kb8tq]

Hi

Have you ever tried to actually *buy* a crystal built to a specification? There 
is a 
tolerance on them. That has a profound impact on what you can *buy*. 

Bob


> On Jun 4, 2017, at 12:56 AM, Donald E. Pauly  wrote:
> 
> You have a fundamental misunderstanding of the AT curve family.  See
> my QBASIC plot at
> http://gonascent.com/papers/hp/hp5061/photos/newxtl.jpg .  The
> commonly described AT cut is shown as the largest sine wave in the
> blue rectangle.  The left side of the rectangle is -55°C, the center
> is 25° C and the right side is 105° C.  The bottom of the rectangle is
> -16 ppm and the top is +16 ppm.
> 
> Main Cut
> Temp   Freq
> -55° C -16 ppm
> -15° C +16 ppm
> +25° C ±0 ppm
> +65° C -16 ppm
> 105° C +16 ppm
> 
> You can get a lower turnover point of 24° C and an upper turnover
> point of 26° C. Their amplitude would be °±0.250 ppb.  As the turnover
> points approach each other, their amplitude approaches zero.  The line
> joining all the turnover points is y= -8·x^3.  The zero temperature
> for 25° is y=4·x^3.  Practical tolerance these days is on the order of
> 0.1 minutes of arc.  This is within the width of the traces in the
> graph.
> 
> You are way off on your 0° to 50° C crystal.
> 
> ["Umm …. errr … it’s quite easy to get a +/- 2 ppm 0-50C AT cut
> *including* the tolerance on the cut angle."]
> 
> Temp   Freq
> 0° C   -0.488 ppb (lower limit)
> 12.5° C  +0.488 ppb (lower turning point)
>   25° C  ±0
> 37.5° C  -0.488 ppb (upper turning point)
>   50° C +0.488 ppb (upper limit)
> 
> As I claimed, a Thermal Electric Cooler has never been used to build a
> crystal oscillator.  In the 50s, TEC efficiencies were on the order of
> 1% and were useless.  The Soviets made coolers more practical in the
> 70s with better materials.  I saw one used at Telemation that was able
> to measure dew point by condensing water vapor on a mirror.  It looks
> like efficiencies have now improved to 33% or so.
> 
> It was only in the early 70s that Analog Devices invented the AD590
> solid state temperature sensor.  It made thermister bridges obsolete.
> Switching amplifiers are required to drive thermal coolers if you want
> to preserve efficiency.
> 
> πθ°μΩω±√·Γλ
> WB0KVV
> 
> -- Forwarded message --
> From: Bob kb8tq 
> Date: Fri, Jun 2, 2017 at 12:22 PM
> Subject: Re: HP5061B Versus HP5071 Cesium Line Frequencies
> To: "Donald E. Pauly" 
> Cc: "rwa...@aol.com" , time-nuts 
> 
> Hi
> 
> Any real crystal you buy will have a tolerance on the angle. In the
> case of a crystal cut for turn the temperature will be a bit different
> and you will match your oven to it. If you attempt a zero angle cut,
> you will never really hit it and there is no way to compensate for the
> problem.
> 
> Bob
> 
> On Jun 2, 2017, at 3:19 PM, Donald E. Pauly  wrote:
> 
> A cut at that angle has no turn over temperature. The zero temperature
> coefficient point is 25°.  Its temperature coefficient everywhere else
> is positive.
> 
> On Friday, June 2, 2017, Bob kb8tq  wrote:
>> 
>> Hi
>> 
>> If you are going to use an oven, it’s better to run it at the turn 
>> temperature of
>> the crystal. That would put you above 50C for an AT and a bit higher still 
>> for an SC.
>> 
>> Bob
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[time-nuts] poor-man's oven

[jimlux]

I recall some years ago folks were talking about putting a PTC 
thermistor on the TCXO of a FlexRadio SDR1000 to stabilize the frequency 
as a sort of poor-man's OCXO.

It's also referenced at
http://www.setileague.org/askdr/xtaloven.htm
where he says "order of magnitude improvement" with no numbers (from 1% 
to 0.1% or from 1 ppb to 0.1 ppb?)


I wonder how well that actually works.

Say you bought an inexpensive (perhaps non TC) XO and an equally 
inexpensive thermistor, glued on on the other, hooked em both up to 3.3 
or 5V.


Yeah, there's issues with room air blowing on it, and tolerances in both 
the XO and thermistor, so your absolute frequency accuracy may not be so 
hot. But what sort of medium to long term performance can one expect.


I did some searches, because I'm sure we've discussed this before, but I 
couldn't find it.  There was some stuff from Oct 2007, but that was in 
the context of a more complex circuit, and the thermistor was the 
sensor. (discussions of TE devices too)

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Re: [time-nuts] Fwd: HP5061B Versus HP5071 Cesium Line Frequencies

[Poul-Henning Kamp]

In message <3ca81847-63c4-f803-994d-8e07c9973...@earthlink.net>, jimlux writes:

>Modern RTDs all are 0.00385 ohm/ohm/degree at 25C.  Typically, you have 
>a 100 ohm device (although there are Pt1000s), so it's changing 0.385 
>ohm/degree.  1 part in 3000

Depending how much money you want to spend, you can also get pt10k
and even pt100k RTD's, to satisfy particular needs for resolution,
self-heating, inductance, mass and the many and varied noises.

And if course, we cannot talk PT100 and fail to repeat the old pun:

"PT100 is the gold standard for temperature measurement"

:-)

-- 
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] Fwd: HP5061B Versus HP5071 Cesium Line Frequencies

[jimlux]

On 6/3/17 9:56 PM, Donald E. Pauly wrote:


It was only in the early 70s that Analog Devices invented the AD590
solid state temperature sensor.  It made thermister bridges obsolete.


There is a difference between something like a platinum resistance 
thermometer (PRT or RTD) and a thermistor, but they both are "measure 
resistance to measure temperature" devices.


Yes, the AD590 is a useful part (I've got some in a device being 
launched in August), but PRTs,thermistors, and thermocouples are still 
widely used.


I don't know that the inherent precision (at room temperature)of the 
various techniques is wildly different.  A 1mV/K signal (AD590 into a 1k 
resistor) has to be measured to 0.1mV for 0.1 degree accuracy.  That's 
out of 300mV, so 1 part in 3000


A type E thermocouple is 1.495 mV at 25C and 1.801 at 30C, so about 0.06 
mV/K slope. Measure 0.006mV for 0.1 degree  (plus the "cold junction" 
issue).  1 part in 250 measurement.


Modern RTDs all are 0.00385 ohm/ohm/degree at 25C.  Typically, you have 
a 100 ohm device (although there are Pt1000s), so it's changing 0.385 
ohm/degree.  1 part in 3000


Checking the Omega catalog.. A 44007 has nominal 5k at 25C, and is 4787 
at 26C, so 1 part in 24.


Especially these days, with computers to deal with nonlinear calibration 
curves, there's an awful lot of TCs and Thermistors in use. The big 
advantage of the AD590 and PRT is that they are basically linear over a 
convenient temperature range.


In a variety applications, other aspects of the measurement device are 
important - ESD sensitivity, tolerance to wildly out of spec temperature 
without damage, radiation effects etc.  Not an issue here, but I'll note 
that the thermistor, PRT, and thermocouple are essentially ESD immune. 
The AD590 most certainly is not.


If you go out and buy cheap industrial PID temperature controller it 
will have input modes for various thermocouples and PRTs.  I suppose 
there's probably some that take 1uA/K, but it's not something I would 
expect.


So I wouldn't say thermistor bridges (or other temperature measurements) 
are obsolete.

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[time-nuts] Fwd: HP5061B Versus HP5071 Cesium Line Frequencies

[Donald E. Pauly]

You have a fundamental misunderstanding of the AT curve family.  See
my QBASIC plot at
http://gonascent.com/papers/hp/hp5061/photos/newxtl.jpg .  The
commonly described AT cut is shown as the largest sine wave in the
blue rectangle.  The left side of the rectangle is -55°C, the center
is 25° C and the right side is 105° C.  The bottom of the rectangle is
-16 ppm and the top is +16 ppm.

Main Cut
Temp   Freq
-55° C -16 ppm
-15° C +16 ppm
+25° C ±0 ppm
+65° C -16 ppm
105° C +16 ppm

You can get a lower turnover point of 24° C and an upper turnover
point of 26° C. Their amplitude would be °±0.250 ppb.  As the turnover
points approach each other, their amplitude approaches zero.  The line
joining all the turnover points is y= -8·x^3.  The zero temperature
for 25° is y=4·x^3.  Practical tolerance these days is on the order of
0.1 minutes of arc.  This is within the width of the traces in the
graph.

You are way off on your 0° to 50° C crystal.

["Umm …. errr … it’s quite easy to get a +/- 2 ppm 0-50C AT cut
*including* the tolerance on the cut angle."]

Temp   Freq
 0° C   -0.488 ppb (lower limit)
12.5° C  +0.488 ppb (lower turning point)
   25° C  ±0
37.5° C  -0.488 ppb (upper turning point)
   50° C +0.488 ppb (upper limit)

As I claimed, a Thermal Electric Cooler has never been used to build a
crystal oscillator.  In the 50s, TEC efficiencies were on the order of
1% and were useless.  The Soviets made coolers more practical in the
70s with better materials.  I saw one used at Telemation that was able
to measure dew point by condensing water vapor on a mirror.  It looks
like efficiencies have now improved to 33% or so.

It was only in the early 70s that Analog Devices invented the AD590
solid state temperature sensor.  It made thermister bridges obsolete.
Switching amplifiers are required to drive thermal coolers if you want
to preserve efficiency.

πθ°μΩω±√·Γλ
WB0KVV

-- Forwarded message --
From: Bob kb8tq 
Date: Fri, Jun 2, 2017 at 12:22 PM
Subject: Re: HP5061B Versus HP5071 Cesium Line Frequencies
To: "Donald E. Pauly" 
Cc: "rwa...@aol.com" , time-nuts 

Hi

Any real crystal you buy will have a tolerance on the angle. In the
case of a crystal cut for turn the temperature will be a bit different
and you will match your oven to it. If you attempt a zero angle cut,
you will never really hit it and there is no way to compensate for the
problem.

Bob

On Jun 2, 2017, at 3:19 PM, Donald E. Pauly  wrote:

A cut at that angle has no turn over temperature. The zero temperature
coefficient point is 25°.  Its temperature coefficient everywhere else
is positive.

On Friday, June 2, 2017, Bob kb8tq  wrote:
>
> Hi
>
> If you are going to use an oven, it’s better to run it at the turn 
> temperature of
> the crystal. That would put you above 50C for an AT and a bit higher still 
> for an SC.
>
> Bob
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