[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] 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"

:-)

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

[jimlux]

On 6/3/17 8:26 PM, Hal Murray wrote:


jim...@earthlink.net said:

I guess the regen receiver must have had some gain at 1 MHz. I found an  old
GE datasheet that gives the ft of 0.6 MHz. (and the hfe wasn't bad,  20, at
DC, probably)



But you sure weren't building a 5MHz or 10 MHz oscillator with a 2N107  or a
CK722.  Or the 2N170 NPN, which I am surprised to find you can  still buy
(and cheaper, in constant dollars, than originally).


Free to good home:

RCA Transistor Manual, SC-10, 1962, $1.50, 300 pages
3/4 of it is Technical Data.  Many 1/2 page.  Some more than a page.
Lots of germanium.  Nothing on the 2N170 or CK722.

GE Transistor Manual, 6th ed, 1962, $2, 440 pages
Nothing resembling a data sheet.  There are several tables with parameters.
The Use column for the 2N170 says IF => Intermediate Frequency Amplifier.




the CK722 was a Raytheon part, I believe.

The 2N170 was apparently hot stuff.  Slightly before my time (2N404 and 
2N1613 were my childhood devices, and amazingly, they're still being 
made, although I suspect not on the same fab lines)


Yep, IF, as in 455 kHz (or back then, 455 kc).  No FM strip at 10.7 MHz 
or TV at 4.5 MHz in 1962.


http://n4trb.com/AmateurRadio/SemiconductorHistory/GE_2N170_NPN_Junction_Transistor.pdf

gives performance *at 455 kHz*.. 24dB gain.  People probably thought 
they had died and gone to heaven.




There is a chapter on Radio Receiver and Tuner Circuits and another on Basic
Computer Circuits.




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

[Hal Murray]

jim...@earthlink.net said:
> I guess the regen receiver must have had some gain at 1 MHz. I found an  old
> GE datasheet that gives the ft of 0.6 MHz. (and the hfe wasn't bad,  20, at
> DC, probably)

> But you sure weren't building a 5MHz or 10 MHz oscillator with a 2N107  or a
> CK722.  Or the 2N170 NPN, which I am surprised to find you can  still buy
> (and cheaper, in constant dollars, than originally). 

Free to good home:

RCA Transistor Manual, SC-10, 1962, $1.50, 300 pages
3/4 of it is Technical Data.  Many 1/2 page.  Some more than a page.
Lots of germanium.  Nothing on the 2N170 or CK722.

GE Transistor Manual, 6th ed, 1962, $2, 440 pages
Nothing resembling a data sheet.  There are several tables with parameters.
The Use column for the 2N170 says IF => Intermediate Frequency Amplifier.

There is a chapter on Radio Receiver and Tuner Circuits and another on Basic 
Computer Circuits.


-- 
These are my opinions.  I hate spam.



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

[jimlux]

On 6/3/17 2:38 PM, Poul-Henning Kamp wrote:


In message 
, "Donald E. Pauly" writes:


Electronic thermal coolers did not exist then


http://www.thermoelectrics.caltech.edu/thermoelectrics/history.html


I'm not sure about fancy coolers.. Yeah, people showed that the effect 
worked, but I think they really didn't come into their own until the 
modern ones that are omnipresent in 12V powered beer coolers and the 
like were developed.  That was 70s according to the article.
Borg Warner (of clutch, brake, and gearbox fame) apparently had one in 
1960.

http://www.thermoelectric.com/2010/archives/library/Ads%20in%20the%2060's.PDF

So they existed, but were pretty exotic. would a crystal oscillator 
builder have wanted to fool with one?  Hey, there have been people 
tinkering with almost everything forever.






Electronic temperature sensors did not exist either.


https://en.wikipedia.org/wiki/Resistance_thermometer#History



Yep... and thermocouples have been used for thermometry for a long time 
too. Thermistors, for that matter, nonlinear as all get-out, but readily 
available.


In the 50s, a *transistor* oscillator would have been pretty unusual. 
I'm not sure they could work at a high enough frequency.  You'll note 
that the early "transistor radios" were basically TRF designs for the AM 
band, and the transistor basically provided audio gain, not RF gain.


http://www.junkbox.com/electronics/sheets/GE_2N107_Datasheet.jpg

I guess the regen receiver must have had some gain at 1 MHz. I found an 
old GE datasheet that gives the ft of 0.6 MHz. (and the hfe wasn't bad, 
20, at DC, probably)


But you sure weren't building a 5MHz or 10 MHz oscillator with a 2N107 
or a CK722.  Or the 2N170 NPN, which I am surprised to find you can 
still buy (and cheaper, in constant dollars, than originally).




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

[Poul-Henning Kamp]

In message 
, "Donald E. Pauly" writes:

>Electronic thermal coolers did not exist then 

http://www.thermoelectrics.caltech.edu/thermoelectrics/history.html

>Electronic temperature sensors did not exist either.

https://en.wikipedia.org/wiki/Resistance_thermometer#History

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

[Poul-Henning Kamp]

In message , jimlux writes:


One final detail about TEC's which people usually don't have to
worry about, is that they're not happy about switching directions.

You generally end up with them mechanically tearing themselves apart
if you use them for mixed cooling/heating.

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

[Bruce Griffiths]

Thermomechanical fatigue can significantly reduce the lifetime of Peltier 
devices if the ripple current flowing in the Peltier device is too high. This 
can become an issue with switchmode drive to a Peltier cooler.

Bruce


> 
> On 03 June 2017 at 11:02 jimlux  wrote:
> 
> On 6/2/17 2:51 PM, Donald E. Pauly wrote:
> 
> > > 
> > This is an improvement of 476 to 1. You apparently have not thought
> > thru what improvements are possible with thermal coolers/heaters.
> > Among these is near instant warm up and greatly reduced power for
> > thermal management.
> > 
> > > 
> without getting into the whole crystal issue, one of the advantages of a
> heater is that it can be VERY simple (and hence reliable, just on a
> parts count basis). With a decent package, once it's hot, the power
> required to keep it hot can be quite low.
> 
> With a heat/cool, you need to be able to have a bipolar supply to the
> peltier device, and they're not particularly efficient (that is, to
> extract 1 Watt of heat, you're putting in significantly more than 1 watt
> of DC, and rejecting 1+X watts to the outside world.
> 
> And then, if you use a linear power supply/amplifier to drive the
> device, that is probably a class A device, and somewhat lossy. A
> switcher would be more efficient, but then you have the problem of
> switching noise, in close proximity to the crystal. You could put a big
> low pass filter in, but now you're adding even more components.
> 
> There are undoubtedly some cases where the thermoelectric scheme would
> work better - for instance, you have a system with a TCXO and it's
> really set up for the TCXO to be at 25C, and you want to regulate that.
> 
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[time-nuts] Fwd: HP5061B Versus HP5071 Cesium Line Frequencies

[Donald E. Pauly]

https://www.febo.com/pipermail/time-nuts/2017-May/105566.html

Electronic thermal coolers did not exist then so it could not be done.
Electronic temperature sensors did not exist either.  That crystal cut
has been known since the 1940's at least.  It has been neglected
because of limited temperature range. It yields ±1 ppm over a range of
±20° C from 25° C.  A slightly different angle of cut can yield ±250
ppb over that range. (4:1 improvement) Contrast that with a normal AT
cut which yields ±9 ppm over that range.

I built an oven with an Analog Devices temperature sensor 20 years
ago.  I did not have time to incorporate foam insulation.  The heater
power was not available to run it at 65° C without insulation.  It had
to run at 40° C and it would hold about 1 ppb over a few hours.   It
would hold the crystal within 0.01° or so but it was far away from the
turnover temperature.   Convection currents cause problems.  It
convinced me that ovens were headaches.   Thermal coolers remove most
of these.

πθ°μΩω±√·Γ
WB0KVV

-- Forwarded message --
From: Bob kb8tq 
Date: Fri, Jun 2, 2017 at 3:50 PM
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 checked out the papers from the 1950 and `1960’s where they
actually tried what you
propose with essentially the same parts you are looking at using?

Bob


> On Jun 2, 2017, at 5:51 PM, Donald E. Pauly  wrote:
>
> # 2 is not true.  A cut has either two turning points or zero.  Where
> both turning points exist there are two temperatures at which the
> temperature coefficient of frequency is zero.  Cut 0 on figure 6 at
> https://coloradocrystal.com/applications has no turnover point.  It is
> neither fish nor fowl.  Cut 6 is the normal AT curve with extremes of
> ±16 ppm for -55° C thru +105° C.  All curves normally intersect at 25°
> C rather than the 27° C shown.  25° C is half way between -55° C thru
> +105° C.  Curve 6 is the Tchebychev polynomial y=4x^3-3x and curve 0
> is y=4x^3.
>
> Consider the standard AT cut which has turnover points at -15° C and
> 65° C.  The lower turnover would ordinarily not be used in ovens.  A
> set point error of ±1° C in the upper turnover point at 65° C results
> in a frequency error of +14.875·10^-9.  For cut 0, that same ±1° error
> in room temperature results in a frequency error of  ±31.25·10^-12.
> This is an improvement of 476 to 1.  You apparently have not thought
> thru what improvements are possible with thermal coolers/heaters.
> Among these is near instant warm up and greatly reduced power for
> thermal management.
>
> πθ°μΩω±√·Γ
> WB0KVV
>
> On Friday, June 2, 2017, Bob kb8tq  wrote:
>>
>> 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
>>
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Re: [time-nuts] Fwd: HP5061B Versus HP5071 Cesium Line Frequencies

[Bruce Griffiths]

With an AT crystal, manufacturing tolerances will likely ensure that the 
inflection point slope is non zero whereas the same manufacturing tolerances 
will merely change the turnover temperature. Its likely that a more 
manufacturable design will result if one operates at a turnover point (with the 
oven temperature adjusted to the actual turnover) than trying to achieve a 
sufficiently low slope at an inflection point. Even for a one off design one 
the selection process required to achieve a sufficiently low slope at the 
inflection point may prove expensive. 

Bruce

> 
> On 03 June 2017 at 09:51 "Donald E. Pauly"  wrote:
> 
> # 2 is not true. A cut has either two turning points or zero. Where
> both turning points exist there are two temperatures at which the
> temperature coefficient of frequency is zero. Cut 0 on figure 6 at
> https://coloradocrystal.com/applications has no turnover point. It is
> neither fish nor fowl. Cut 6 is the normal AT curve with extremes of
> ±16 ppm for -55° C thru +105° C. All curves normally intersect at 25°
> C rather than the 27° C shown. 25° C is half way between -55° C thru
> +105° C. Curve 6 is the Tchebychev polynomial y=4x^3-3x and curve 0
> is y=4x^3.
> 
> Consider the standard AT cut which has turnover points at -15° C and
> 65° C. The lower turnover would ordinarily not be used in ovens. A
> set point error of ±1° C in the upper turnover point at 65° C results
> in a frequency error of +14.875·10^-9. For cut 0, that same ±1° error
> in room temperature results in a frequency error of ±31.25·10^-12.
> This is an improvement of 476 to 1. You apparently have not thought
> thru what improvements are possible with thermal coolers/heaters.
> Among these is near instant warm up and greatly reduced power for
> thermal management.
> 
> πθ°μΩω±√·Γ
> WB0KVV
> 
> -- Forwarded message --
> From: Bob kb8tq 
> Date: Fri, Jun 2, 2017 at 12:43 PM
> Subject: Re: HP5061B Versus HP5071 Cesium Line Frequencies
> To: "Donald E. Pauly" 
> 
> Hi
> 
> Which statement is not true:
> 
> 1) That there is a tolerance on the cut angle of a crystal?
> 
> 2) That true zero temperature coefficient only happens at the turn?
> 
> 3) That heater based controllers are impossible to build?
> 
> Bob
> 
> On Jun 2, 2017, at 3:40 PM, Donald E. Pauly  
> wrote:
> 
> That is not true. I say that thermal coolers have made ovens
> obsolete. A zero temperature coefficient at room temperature is
> easier to hit than a zero temperature at the upper turnover point when
> such a thing exists. See
> curve 0 in Figure 6 at https://coloradocrystal.com/applications/ .
> 
> πθ°μΩω±√·Γ
> WB0KVV
> 
> On Friday, June 2, 2017, Bob kb8tq  wrote:
> >
> 
> > > 
> > 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
> > 
> > ___
> > 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] Fwd: HP5061B Versus HP5071 Cesium Line Frequencies

[jimlux]

On 6/2/17 2:51 PM, Donald E. Pauly wrote:



This is an improvement of 476 to 1.  You apparently have not thought
thru what improvements are possible with thermal coolers/heaters.
Among these is near instant warm up and greatly reduced power for
thermal management.


without getting into the whole crystal issue, one of the advantages of a 
heater is that it can be VERY simple (and hence reliable, just on a 
parts count basis). With a decent package, once it's hot, the power 
required to keep it hot can be quite low.


With a heat/cool, you need to be able to have a bipolar supply to the 
peltier device, and they're not particularly efficient (that is, to 
extract 1 Watt of heat, you're putting in significantly more than 1 watt 
of DC, and rejecting 1+X watts to the outside world.


And then, if you use a linear power supply/amplifier to drive the 
device, that is probably a class A device, and somewhat lossy.  A 
switcher would be more efficient, but then you have the problem of 
switching noise, in close proximity to the crystal. You could put a big 
low pass filter in, but now you're adding even more components.


There are undoubtedly some cases where the thermoelectric scheme would 
work better - for instance, you have a system with a TCXO and it's 
really set up for the TCXO to be at 25C, and you want to regulate that.

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

[Donald E. Pauly]

# 2 is not true.  A cut has either two turning points or zero.  Where
both turning points exist there are two temperatures at which the
temperature coefficient of frequency is zero.  Cut 0 on figure 6 at
https://coloradocrystal.com/applications has no turnover point.  It is
neither fish nor fowl.  Cut 6 is the normal AT curve with extremes of
±16 ppm for -55° C thru +105° C.  All curves normally intersect at 25°
C rather than the 27° C shown.  25° C is half way between -55° C thru
+105° C.  Curve 6 is the Tchebychev polynomial y=4x^3-3x and curve 0
is y=4x^3.

Consider the standard AT cut which has turnover points at -15° C and
65° C.  The lower turnover would ordinarily not be used in ovens.  A
set point error of ±1° C in the upper turnover point at 65° C results
in a frequency error of +14.875·10^-9.  For cut 0, that same ±1° error
in room temperature results in a frequency error of  ±31.25·10^-12.
This is an improvement of 476 to 1.  You apparently have not thought
thru what improvements are possible with thermal coolers/heaters.
Among these is near instant warm up and greatly reduced power for
thermal management.

πθ°μΩω±√·Γ
WB0KVV

-- Forwarded message --
From: Bob kb8tq 
Date: Fri, Jun 2, 2017 at 12:43 PM
Subject: Re: HP5061B Versus HP5071 Cesium Line Frequencies
To: "Donald E. Pauly" 

Hi

Which statement is not true:

1) That there is a tolerance on the cut angle of a crystal?

2) That true zero temperature coefficient only happens at the turn?

3) That heater based controllers are impossible to build?

Bob

On Jun 2, 2017, at 3:40 PM, Donald E. Pauly  wrote:

That is not true.  I say that thermal coolers have made ovens
obsolete.  A zero temperature coefficient at room temperature is
easier to hit than a zero temperature at the upper turnover point when
such a thing exists.  See
curve 0 in Figure 6 at https://coloradocrystal.com/applications/ .

πθ°μΩω±√·Γ
WB0KVV


On Friday, June 2, 2017, Bob kb8tq  wrote:
>
> 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
>
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[time-nuts] Fwd: HP5061B Versus HP5071 Cesium Line Frequencies

[Donald E. Pauly]

https://www.febo.com/pipermail/time-nuts/2017-May/105566.html

If we build this circuit it would be a bench model not designed to be
inside a hot chassis.  It would be able to lock ± 5° C of 25° C.  My
idea of an oven is to keep the crystal and oscillator at 25° C ±0.001
°C with 60 second warm up/cool down time.

πθ°μΩω±√·Γλ
WB0KVV

-- Forwarded message --
From: Bob kb8tq 
Date: Fri, Jun 2, 2017 at 5:57 AM
Subject: Re: [time-nuts] HP5061B Versus HP5071 Cesium Line Frequencies
To: Discussion of precise time and frequency measurement 

Hi

I would suggest you check a few real crystals over the 20 to 40C range ….
With all the “stuff” in a 5061, it will change (rise) at least 10C
after turn on.

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

[Donald E. Pauly]

https://www.febo.com/pipermail/time-nuts/2017-May/105500.html

We recently did a partial alignment of the lock servo on our #2
HP5061B after replacing the beam tube. The previous owner had tried to
fix it by turning adjustments.  This made a big improvement in the
lock.  KB7APQ got the idea to use the audio spectrum analyzer in his I
Phone to measure the noise output of the beam tube.

We used the Beam I meter driver emitter follower for an audio source.
It provides about 0.4 Volts per 25 uA on the meter.  A 100 ohm safety
resistor was in series with Q6 emitter on the A7 board.  It was
followed by a 100 nFd condenser into the 100 k input impedance of the
I phone.  Low frequency cutoff is about 16 cps.

See http://gonascent.com/papers/hp/hp5061/waveform/spectrum.jpg .
Start frequency is 4 cps and each bin is 8 cps wide.  Center frequency
of each bin is 8 cps higher than the one before it.  Frequency and
amplitude are both logarithmic.  Amplitude is 12 db per division.  The
first three bands show the low frequency rolloff of the coupling
condenser.  Five harmonics of the 137 cps modulation frequency can be
seen.

For unknown reasons, a sharp null in the noise of about 2 db at 137
cps is seen.  The servo nulls the 137 cps there but I can't see how
the noise could be nulled.  The prominent second harmonic at 274 cps
is normal.  It measures -74 db below reference.  I calculated it at
about 0.15 V pp or 53 mV rms.  The third harmonic at 411 cps again
shows up as a 2 db noise null for unknown reasons.The fourth harmonic
at 548 cps cannot be seen. The fifth harmonic at 685 cps barely breaks
thru the lower limit of the spectrum analyzer.

It looks like rectifier pulse harmonics can be seen at 120 cps.  They
may be getting thru the mu metal shields of the beam tube.  That
frequency is right on the border of two bins.  360 cps third harmonic
of rectifier pulses can be seen.  It appears in the middle of a bin.
An unknown signal is seen at 564 cps.  This could be the +3500 power
supply frequency.

1 cps bandwidth noise in the 50 to 100 cps area seems to be about 20
db below the 274 cps second harmonic.  This will determine the
possible lock improvement with improved modulation methods.

πθ°μΩω±√·Γλ
WB0KV


-- Forwarded message --
From: Bob kb8tq 
Date: Sat, May 27, 2017 at 6:01 PM
Subject: Re: [time-nuts] HP5061B Versus HP5071 Cesium Line Frequencies
To: Discussion of precise time and frequency measurement 

Hi

Having run a 5071A with a *very* good 10811 in it, the OCXO does
dictate what happens at 0.1 seconds. Once you get past that, you are
headed into a bit of a gray zone. You are partly looking at the Cs and
partly looking at the OCXO. Pushing out the crossover between the two
could help you at 1 second. The gotcha is that the “hump” will still
be there, just a bit further out. The net effect at (say) 100 seconds
could easily be worse
with the “fix”.

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

[paul swed]

Though I will never see a OSA 3000, It certainly sounds like a hack could
be done to obtain a Cs off reference. But then when you don't actually have
one you can make comments like that.
Sounds nice.
Regards
Paul
WB8TSL

On Sun, May 28, 2017 at 8:20 AM, Magnus Danielson <
mag...@rubidium.dyndns.org> wrote:

> Hi,
>
> On 05/28/2017 11:52 AM, "Björn Gabrielsson" wrote:
>
>> So while I'm eager to see Donald's results, I question their merit. The
>>>
>> 5061 standards already have a very convenient Cs-Off switch right on the
>> front panel. It is there so you get the pure 10811 performance when you
>> need it. Use it. In fact there's lots of people run their precious 5061
>> in
>>
>>> Cs-Off mode 23.9 hours a day and just turn on the Cs once a day, or once
>>>
>> a
>>
>>> week, to re-cal the oscillator. It's not there just to conserve cesium;
>>>
>> you also get full 10811 short-term performance. Note also some 5061 have
>> a
>>
>>> short/long time-constant switch which also helps you tailor the ADEV you
>>>
>> want out of the instrument.
>>
>>> /tvb
>>>
>>
>> Very nice design by HP.
>>
>> For the same era design, the OSA (telecom) module made other choices. When
>> turning off CS, they turn off power to the output module and the efc
>> tuning circuit.
>>
>> So even if there is a nice and warm BVA inside - without burning CS - the
>> standard output is not working and also its off any manual tuning.
>>
>
> In addition, and I consider this somewhat of a design flaw, the external
> voltage reference to the oscillator (pre-BVA or BVA) is also powered of, so
> it drift south rather than stay put. Otherwise it would have been easy to
> trim the oscillator for zero lock enforcement and then free-wheel on the
> OCXO when Cs is powered down.
>
> The OSA 3000 and 3100 cesiums are nice analog cesiums, but lacking the
> refinement of digitally controlled that came later.
>
> Cheers,
> Magnus
>
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Re: [time-nuts] Fwd: HP5061B Versus HP5071 Cesium Line Frequencies

[Magnus Danielson]

Hi,

On 05/28/2017 11:52 AM, "Björn Gabrielsson" wrote:

So while I'm eager to see Donald's results, I question their merit. The

5061 standards already have a very convenient Cs-Off switch right on the
front panel. It is there so you get the pure 10811 performance when you
need it. Use it. In fact there's lots of people run their precious 5061
in

Cs-Off mode 23.9 hours a day and just turn on the Cs once a day, or once

a

week, to re-cal the oscillator. It's not there just to conserve cesium;

you also get full 10811 short-term performance. Note also some 5061 have
a

short/long time-constant switch which also helps you tailor the ADEV you

want out of the instrument.

/tvb


Very nice design by HP.

For the same era design, the OSA (telecom) module made other choices. When
turning off CS, they turn off power to the output module and the efc
tuning circuit.

So even if there is a nice and warm BVA inside - without burning CS - the
standard output is not working and also its off any manual tuning.


In addition, and I consider this somewhat of a design flaw, the external 
voltage reference to the oscillator (pre-BVA or BVA) is also powered of, 
so it drift south rather than stay put. Otherwise it would have been 
easy to trim the oscillator for zero lock enforcement and then 
free-wheel on the OCXO when Cs is powered down.


The OSA 3000 and 3100 cesiums are nice analog cesiums, but lacking the 
refinement of digitally controlled that came later.


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

[Björn Gabrielsson]

> So while I'm eager to see Donald's results, I question their merit. The
5061 standards already have a very convenient Cs-Off switch right on the
front panel. It is there so you get the pure 10811 performance when you
need it. Use it. In fact there's lots of people run their precious 5061
in
> Cs-Off mode 23.9 hours a day and just turn on the Cs once a day, or once
a
> week, to re-cal the oscillator. It's not there just to conserve cesium;
you also get full 10811 short-term performance. Note also some 5061 have
a
> short/long time-constant switch which also helps you tailor the ADEV you
want out of the instrument.
> /tvb

Very nice design by HP.

For the same era design, the OSA (telecom) module made other choices. When
turning off CS, they turn off power to the output module and the efc
tuning circuit.

So even if there is a nice and warm BVA inside - without burning CS - the
standard output is not working and also its off any manual tuning.

--

Björn




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

[Tom Van Baak]

I agree with some of what Donald and Rick are saying.

But does anyone actually use a locked Cs standard for its short-term stability 
(e.g., tau < 10 s)? If that's your goal then what you do is run the standard in 
Cs-Off (free-run, standby) mode. Or just use best old OCXO you can find and 
forget the cesium entirely. I don't use a 5061/5071 as a short-term ref. For 
that a hand-picked FTS 1000/1200-series, or hp 10811, or Wenzel ULN, or BVA is 
much better. It's rare that you need both extreme long-term accuracy and 
extreme short-term stability at the same time, so this approach works well.

So while I'm eager to see Donald's results, I question their merit. The 5061 
standards already have a very convenient Cs-Off switch right on the front 
panel. It is there so you get the pure 10811 performance when you need it. Use 
it. In fact there's lots of people run their precious 5061 in Cs-Off mode 23.9 
hours a day and just turn on the Cs once a day, or once a week, to re-cal the 
oscillator. It's not there just to conserve cesium; you also get full 10811 
short-term performance. Note also some 5061 have a short/long time-constant 
switch which also helps you tailor the ADEV you want out of the instrument.

/tvb

- Original Message - 
From: "Richard (Rick) Karlquist" <rich...@karlquist.com>
To: "Discussion of precise time and frequency measurement" 
<time-nuts@febo.com>; "Donald E. Pauly" <trojancow...@gmail.com>
Sent: Saturday, May 27, 2017 5:15 PM
Subject: Re: [time-nuts] Fwd: HP5061B Versus HP5071 Cesium Line Frequencies


On 5/27/2017 2:08 PM, Donald E. Pauly wrote:

> I am investigating the total redesign of the HP5061B lock system for
> vastly improved performance.  It looks like the performance of the
> HP5071A can be beaten by 10 to 1 for averaging times on the order of a
> few seconds.
> 
> πθ°μΩω±√·Γλ
> WB0KV
> 

That's an interesting claim, but it could be valid.
The 5071A flywheel is a 10811 selected for performance
and modified to have additional electronic tuning
range (I was involved in that) but otherwise it is
plain vanilla 10811.  At a few seconds averaging time,
this oscillator is basically open loop.  It might be
possible to improve a 5071A by simply finding a 10811
with exceptional short term stability.  The tail of
the distribution curve went down at least an order of
magnitude, according to Jack Kusters at HP.

In any event, you could use an unmodified 5071A or maybe
a 5061B high performance option and discipline some
really good XO.  Certainly, the 10811 isn't the world's best
XO.  You'll need to prevent your XO from getting bothered
by microphonics, stray magnetic fields, 2G turnover, temperature
fluctuations, and humidity if not hermetic , etc.  The 5071A is
impervious to all that as it is.

Is that what you had in mind?

I remember before I worked for HP visiting JPL's Goldstone
tracking station.  They had a 5061A that disciplined a
hydrogen maser for VLBI.  They said a plain 5061A was useless for their
work.  OTOH, a hydrogen maser without drift correction was
also useless for their work.  They had a huge room with 100's
of racks of equipment, but the 5061A and H maser had their
own dedicated room.

Rick Karlquist N6RK
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Re: [time-nuts] Fwd: HP5061B Versus HP5071 Cesium Line Frequencies

[Richard (Rick) Karlquist]

On 5/27/2017 2:08 PM, Donald E. Pauly wrote:


I am investigating the total redesign of the HP5061B lock system for
vastly improved performance.  It looks like the performance of the
HP5071A can be beaten by 10 to 1 for averaging times on the order of a
few seconds.

πθ°μΩω±√·Γλ
WB0KV



That's an interesting claim, but it could be valid.
The 5071A flywheel is a 10811 selected for performance
and modified to have additional electronic tuning
range (I was involved in that) but otherwise it is
plain vanilla 10811.  At a few seconds averaging time,
this oscillator is basically open loop.  It might be
possible to improve a 5071A by simply finding a 10811
with exceptional short term stability.  The tail of
the distribution curve went down at least an order of
magnitude, according to Jack Kusters at HP.

In any event, you could use an unmodified 5071A or maybe
a 5061B high performance option and discipline some
really good XO.  Certainly, the 10811 isn't the world's best
XO.  You'll need to prevent your XO from getting bothered
by microphonics, stray magnetic fields, 2G turnover, temperature
fluctuations, and humidity if not hermetic , etc.  The 5071A is
impervious to all that as it is.

Is that what you had in mind?

I remember before I worked for HP visiting JPL's Goldstone
tracking station.  They had a 5061A that disciplined a
hydrogen maser for VLBI.  They said a plain 5061A was useless for their
work.  OTOH, a hydrogen maser without drift correction was
also useless for their work.  They had a huge room with 100's
of racks of equipment, but the 5061A and H maser had their
own dedicated room.

Rick Karlquist N6RK
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[time-nuts] Fwd: HP5061B Versus HP5071 Cesium Line Frequencies

[Donald E. Pauly]

Tom:

The Greek letters are my pallet for common electronic letters.  I
transposed two items in my last post and here they are corrected.
Note that the √(frequency error)=ratio of Zeeman frequencies as well
as ratio of C fields.

model/freq error cps/Zeeman freq kc/C field/(milliGauss)

5061A 1.59 42.82 61 mG
5061B 2.50 53.53 76 mG
5062C 4.30 70.40 (100 mG?)

I am investigating the total redesign of the HP5061B lock system for
vastly improved performance.  It looks like the performance of the
HP5071A can be beaten by 10 to 1 for averaging times on the order of a
few seconds.

πθ°μΩω±√·Γλ
WB0KV

-- Forwarded message --
From: Tom Van Baak 
Date: Fri, May 26, 2017 at 5:36 PM
Subject: Re: HP5061B Versus HP5071 Cesium Line Frequencies
To: "Donald E. Pauly" 

Donald,

I'm enjoying many of your 5061 posts the past few months. Fun isn't
is? Thanks for taking the time sharing them with the group.

Question...

> πθ°μΩω±√·Γλ

What's that Greek mean (70 3F B0 B5 4F 3F B1 76 B7 47 3F)?

Thanks,
/tvb
Moderator, http://leapsecond.com/time-nuts.htm
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[time-nuts] Fwd: HP5061B Versus HP5071 Cesium Line Frequencies

[Donald E. Pauly]

https://www.febo.com/pipermail/time-nuts/2017-May/105298.html

Those were interesting links. C field levels are a small fraction of
the earth's field of 700 milliGauss.  The C field winding is a few
turns inside the beam tube.  They are driven by several different
possible currents depending upon the desired frequency correction.
For the HP5061B it is 24.5 mA for the standard tube at 100%.  At the
0% point of the C field, the cesium resonance is unaffected.  At the
50% point, it is shifted upward by the amount of error in the
microwave frequency.  This varies depending on synthesizer design.  At
the 100% point, the error is reversed to give a reverse adjustment
range equal to the original error.

An electron orbits in a magnetic field with frequency f=qB/(2πm).
(q=charge, B=field strength, m=electron mass)  The Zeeman frequency is
the same as the frequency of an electron orbit in a field equal to 25%
of C field listed.  The square of the C field gives the frequency
shift in the cesium line.  I saw 90 mG listed for the 5062C but I
think that it should be 100 mG.

There is a test for the beam tube when the rf drive is removed and the
LF coil is driven with a frequency equal to half the Zeeman frequency.
It induces a peak that checks the operation of the tube without rf.
Does anyone know what is actually going on then?  We had a bad beam
tube that failed this test.

model|freq error cps|Zeeman freq kc|C field|(milliGauss)
5061A 2.50 53.53 76 mG
5061B 1.59 42.82 61 mG
5062C 4.30 70.40 (100 mG?)

πθ°μΩω±√·Γλ
WB0KV


-- Forwarded message --
From: Tom Van Baak 
Date: Thu, May 25, 2017 at 9:23 PM
Subject: Re: [time-nuts] HP5061B Versus HP5071 Cesium Line Frequencies
To: Discussion of precise time and frequency measurement 


Donald,

You're familiar with the 9,192,631,770 Hz definition of the SI second;
but that's only for an "unperturbed" atom. The bad news is that in
order to make the cesium beam operate at the central resonance peak
one actually has to violate the SI definition and perturb it -- by
applying a magnetic field (the so-called C-field), as well as other
factors. This cannot be avoided. The good news is that the shift can
be calculated.

In other words, because a magnetic field must be applied the actual
cesium resonance frequency is not 9192.631770 MHz. The synthesizer
locks to the peak, but the peak is at a slightly higher frequency than
the nominal book value. This detailed note from hp may help:

http://leapsecond.com/museum/hp5062c/theory.htm

Different model beam tubes use different field strength / Zeeman
frequency. Search the archives for lots of good postings about all
these magic frequencies -- google: site:febo.com zeeman

If you want to see what the resonance peaks (all 7 of them) actually
look after the C-field is applied see:

http://leapsecond.com/pages/cspeak/
and (poster size):
http://leapsecond.com/pages/cfield/

See also John's version:

http://www.ke5fx.com/cs.htm

One final comment -- the perturbed vs. unperturbed issue is far more
complex than a single correction. To get an idea of the math and
physics complexity of a laboratory Cs beam standard read some of
these:

http://tf.nist.gov/general/pdf/1497.pdf
http://tf.nist.gov/general/pdf/65.pdf
http://tf.boulder.nist.gov/general/pdf/101.pdf

/tvb

- Original Message -
From: "Donald E. Pauly" 
To: "time-nuts" ; "Donald E. Pauly" 
Sent: Thursday, May 25, 2017 7:55 PM
Subject: [time-nuts] HP5061B Versus HP5071 Cesium Line Frequencies


https://www.febo.com/pipermail/time-nuts/2017-May/105298.html

The synthesizer in the HP5061B generates a frequency of about
9,192,631,772.5 cps when the 5 mc oscillator is exactly on frequency.
First the 5 mc oscillator is multiplied by 18 to 90 mc on the A1
board.  That in turn is multiplied by 102 in the A4 board to give
9,180 mc.

The 5 mc is also divided by 4079 to produce 1,225.790635 cps.  That in
turn is multiplied by 10,305 to produce 12,631,772.5 cps.  This is
added to the 9180 mc in the A4 mixer to produce the final frequency of
9,192,631,772.5 cps approximately.  This is higher than the defined
frequency of 9,192,631,770 cps by about 2.5 cps or 271·10^-12.  If I
figured it right, the C field adjustment only has a range of
40·10^-12.  This seems to be insufficient to put the standard on
frequency.

Can anyone explain these mysteries?  Does anyone know why this
frequency was chosen?  Does anyone know the choice for the frequency
of the HP5071 cesium?

πθ°μΩω±√·Γλ
WB0KV
4,079=prime
10,305=5x9x229
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