4:35 PM
Subject: Re: [time-nuts] Improving the stability of crystal oscillators
Don Collie wrote:
Dear Dr Bruce,
I am partially depantsed [*only* partially]. Do I have your
permission to respond to your points on group? This way either you, or
I will be fully depantsed.
All the best
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Enough speculation on ground temperatures.
The attenuation of cyclic variations of surface temperature die away
at an exponential rate with depth.
The thermal diffusivity of soils does vary but not so you can not
generalise.
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In a message dated 10/14/2007 23:07:04 Pacific Daylight Time,
[EMAIL PROTECTED] writes:
Thermal transients propagate into the ground on a different law,
Gauss' Error Function.
If the ground is cleared of trees, one
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Dear all,
the major problem for the use of a Peltier cell with
a quartz oscillator is that the cell maximum operating
temperature is of the order of 80 degrees Celsius.
This is due to the low melting point of the metal pairs
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The resonator inversion temperature occurs at 70-80 degrees Celsius,
depending on the cut angles.
Is there something magic about quartz that has a turnover in the region that
just happens to be handy for OCXOs? Or is it
,Don C.
- Original Message -
From: Hal Murray [EMAIL PROTECTED]
To: Discussion of precise time and frequency measurement
time-nuts@febo.com
Sent: Tuesday, October 16, 2007 5:49 AM
Subject: Re: [time-nuts] Improving the stability of crystal oscillators
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, October 15, 2007 10:12 PM
Subject: Re: [time-nuts] Improving the stability of crystal oscillators
As far as I can tell, temperature curve plots for quartz typically
show both an upper and a lower turnover point (for example,
see the pages below). Since the upper is well above maximum
ambient
Don Collie wrote:
Hi Hal,
I was thinking of attaching a temparature sensor [AKA Star Treck] to the
cold side of a Peltier [what`s the other type? Are they available/better?]
pile. and driving the pile from the output of some sort of servo loop to
maintain a temparature of ,say , 0
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The required depth depends on the soil diffusivity and the temperature
stability required.
It is instructive to install thermometers at depth intervals of a foot
or so and record the temperature fluctuations experienced by
From: John Miles [EMAIL PROTECTED]
Subject: Re: [time-nuts] Improving the stability of crystal oscillators
Date: Sun, 14 Oct 2007 14:15:10 -0700
Message-ID: [EMAIL PROTECTED]
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The required depth depends on the soil
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Hi Bruce:
All the papers are for depths on the order of a few feet, aimed at plant
growth, nevertheless in all cases the temperature was changing by at least 1
deg c at the deepest depth recorded.
I've heard there is some
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I've heard there is some depth that building foundations need to be so
they don't get winter frost heave that might be on the order of a
couple of feet, but that's far different from an constant temperature
depth.
That
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Has anyone concidered using a small Peltier pile to maintain the crystal`s
temparature. I understand that these devices will heat or cool, so it would
be possible to maintain the crystal temparature at , say, 25 degrees
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Hi Don:
They are very inefficient to the point that a system that's supposed to cool
something may heat it because of all the heat generated by the module.
It takes a huge amount of heat sinking or liquid cooling to get them
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Hi:
Something I've been thinking about is attaching a large thermal mass of
aluminum to the crystal and it's oscillator then surrounding that with
insulation. Then surround that with a thin copper layer. Temperature
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Brooke Clarke wrote:
Hi:
Something I've been thinking about is attaching a large thermal mass of
aluminum to the crystal and it's oscillator then surrounding that with
insulation. Then surround that with a thin copper
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Nah, not for this application. A Peltier module typically has a COP of 1.
That is,
it moves a watt of energy for each watt consumed. Thus, for each watt moved,
two
watts have to be dissipated to air.
I can't imagine a
Brooke Clarke wrote:
Hi Don:
They are very inefficient to the point that a system that's supposed to cool
something may heat it because of all the heat generated by the module.
It takes a huge amount of heat sinking or liquid cooling to get them to work.
Have Fun,
Brooke Clarke
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Don Collie [EMAIL PROTECTED] wrote:
Has anyone concidered using a small Peltier pile to maintain the crystal`s
temparature. I understand that these devices will heat or cool, so it would
be possible to maintain the crystal
time-nuts@febo.com
Subject: Re: [time-nuts] Improving the stability of crystal oscillators
Brooke Clarke wrote:
Hi:
Something I've been thinking about is attaching a large thermal mass of
aluminum to the crystal and it's oscillator then surrounding that with
insulation. Then surround
I doug up and included below a time-nuts email from a couple of years
ago on improving oscillator stability, with some thoughts from Jack
Kusters, Tom Clark, and Brooke Clarke.
Also, there's a good history of high precision oscillators at:
http://www.ieee-uffc.org/fc_history/norton.html
PROTECTED]
Sent: Oct 13, 2007 2:44 PM
To: Discussion of precise time and frequency measurement time-nuts@febo.com
Subject: Re: [time-nuts] Improving the stability of crystal oscillators
Brooke Clarke wrote:
Hi:
Something I've been thinking about is attaching a large thermal mass of
aluminum
time and frequency measurement
time-nuts@febo.com
Sent: Sunday, October 14, 2007 11:19 AM
Subject: Re: [time-nuts] Improving the stability of crystal oscillators
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Nah, not for this application. A Peltier module typically
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Brooke Clarke wrote:
Hi Bruce:
I've also looked into drilling a hole (garden hose, 90 deg fitting pipe
with
end smashed flat to make a nozzle will easily drill as deep as the pipe is
long). Then using a short length
Hi Bruce:
Details on your experiment please.
Hole/pipe diameter, material?
Depth?
Delta T at different depths vs surface ambient?
Soil type?
Have Fun,
Brooke Clarke
http://www.PRC68.com
http://www.precisionclock.com
http://www.prc68.com/I/WebCam2.shtml 24/7 Sky-Weather-Astronomy Cam
Bruce
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Brooke Clarke wrote:
Hi Bruce:
Details on your experiment please.
Hole/pipe diameter, material?
Depth?
Delta T at different depths vs surface ambient?
Soil type?
Have Fun,
Brooke Clarke
Booke
I will try to find
Brooke Clarke wrote:
Hi Bruce:
Details on your experiment please.
Hole/pipe diameter, material?
Depth?
Delta T at different depths vs surface ambient?
Soil type?
Have Fun,
Brooke Clarke
Brooke
Unable as yet to find my data, it was published in some very obscure
publication if I
stability for 134GHz local
oscillator usage
Dave
Message: 1
Date: Wed, 10 Oct 2007 10:14:28 -0700 (PDT)
From: Tom Clifton [EMAIL PROTECTED]
Subject: [time-nuts] Improving the stability of crystal oscillators
To: time-nuts@febo.com
Message-ID: [EMAIL PROTECTED]
Content-Type: text/plain
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Hi All,
I am not trying to start an argument, but I would like to point out
that PID controllers are only
good at controlling a certain class of system.
For a system that has a coal truck that must dump its coal down a
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Maybe because it was written back in 1930's, but one of the better
discussions of quartz temperature control, including considerations
of insulation and isothermal layers (attenuation and conduction)
are in the patents for the
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Neville Michie wrote:
Hi All,
I am not trying to start an argument, but I would like to point out
that PID controllers are only
good at controlling a certain class of system.
For a system that has a coal truck that must
Neville Michie wrote:
I am not trying to start an argument, but I would like to point out
that PID controllers are only
good at controlling a certain class of system.
The thermal block controllers work well because of the dominant
integrating effect of the block,
the time delay for a
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The 10811 has an ANALOG oven control loop. The gain is set
to be just below the oscillation point. This is due to the
stability limits dictated by the oven mass and (believe it
or not) the size of integrator capacitor that
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At HP, in the 90's, we did a lot of brainstorming about vacuum ovens.
This never seemed to make sense to us. If you actually
achieve high amounts of thermal resistance, then you can't
get the heat out of the oven. And if you
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Hi Tom:
Very interesting. How about building a circuit to drive those GR crystals?
The same man is the inventor of all four of the early GR patents, James Kilton
Clapp, of Clapp Oscillator fame.
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On 11/10/2007, at 10:23 PM, Bruce Griffiths wrote:
If one uses resistive heating then some linearisation improves the
performance as the heat from the heating element is proportional to
the
square of the voltage across
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Neville Michie wrote:
If you use a transistor as a heater, the full supply voltage is
across the
element all the time, so heating is proportional to the current flowing.
Neville
Neville
However using a transistor
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[EMAIL PROTECTED] wrote:
Hi Rick,
thanks for the pointers to the E1938A oven quality.
Today there are some interesting new technologies which allow small double,
or even tripple (not sure if that makes sense) ovens
We went through this tradeoff on the E1938A. Resistive heaters
can be distributed. However, it is very inefficient to drive
them with transistors, because then you waste a lot of power
heating the transistors, which is waste heat if resistive heating
is used. Prior to the 10544, they just put
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Rick Karlquist N6RK wrote:
If you want to soup up at 10811 oven, externally wire in a
larger capacitor in parallel and change the resistors to increase
the gain. The 10811 designers did the best they could with
what they
From: Bruce Griffiths [EMAIL PROTECTED]
Subject: Re: [time-nuts] Improving the stability of crystal oscillators
Date: Fri, 12 Oct 2007 10:08:34 +1300
Message-ID: [EMAIL PROTECTED]
Hej Bruce and Neville,
Neville Michie wrote:
If you use a transistor as a heater, the full supply voltage
In a message dated 10/11/2007 14:31:04 Pacific Daylight Time,
[EMAIL PROTECTED] writes:
The lack of radiation shields and an isothermal block enclosing the
oscillator components within the vacuum will surely reduce the
performance somewhat.
Bruce
Hi Bruce,
yes I would agree, the spec
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In a message dated 10/11/2007 11:52:37 Pacific Daylight Time,
[EMAIL PROTECTED] writes:
Maybe Vectron has figured out something we didn't think of or
has sufficiently difference constraints that a vacuum makes
sense for
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While the website is not explicitly about frequency
measurement, there is an interesting bit on improving
the stability of crystal oscillators with external
heater controllers. While it may not be suitable for
long term high
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Hi Tom:
That's a cleaver improvement to a non ovenized crystal. Usually crystals are
ground to have a temp vs freq turnover point occur at a specified temperature.
The common one is to be on frequency at room temperature.
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This is getting off topic (because it's far to practical!) but hanging
heaters on crystals is a time-honored activity for hams. Many of the
surplus FM rigs for VHF and UHF that we obtained from the likes of
Motorola, GE, RCA,
In a message dated 10/10/2007 11:13:21 Pacific Daylight Time, [EMAIL PROTECTED]
writes:
We first built a small proportional heater circuit that we could shove
in next to the crystal, and that worked OK. We finally found a source
for thermistors spot welded to a spring clip that would mount
[EMAIL PROTECTED] said the following on 10/10/2007 02:17 PM:
In a message dated 10/10/2007 11:13:21 Pacific Daylight Time, [EMAIL
PROTECTED]
writes:
We first built a small proportional heater circuit that we could shove
in next to the crystal, and that worked OK. We finally found a
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[EMAIL PROTECTED] said the following on 10/10/2007 02:39 PM:
BTW: I wonder how much effect thermistor and resistor-bridge aging as well
as opamp offset drift has on the long term aging of typical OCXO's since it
will
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In a message dated 10/10/2007 11:34:43 Pacific Daylight Time, [EMAIL PROTECTED]
writes:
heater design: http://www.febo.com/hamdocs/d4art.html. The quality of
the heater schematic isn't very good, but it's all I have.
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Try DigiKey pn: 235-1123-ND for a simple PTC Thermistor that can be
soldered to the xtal case if one were so inclined. Do so at your own
risk to the xtal!
-Brian
-- Original message --
From:
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In a message dated 10/10/2007 19:34:55 GMT Daylight Time, [EMAIL PROTECTED]
writes:
We bought them as a replacement part from Yaesu USA. This data is 10
years or more old, but here you go:
Part NameYaesu Part Number
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Hi Brian:
I used to use Balco (as far as I can remember) positive coefficient resistors
that had specs similar to the Digikey units you linked to. These were only
available in values under 200 Ohms and have a positive
From: [EMAIL PROTECTED]
Subject: Re: [time-nuts] Improving the stability of crystal oscillators
Date: Wed, 10 Oct 2007 14:17:24 EDT
Message-ID: [EMAIL PROTECTED]
John,
In a message dated 10/10/2007 11:13:21 Pacific Daylight Time, [EMAIL
PROTECTED]
writes:
We first built a small
...) for about 15 years.
Didier KO4BB
-Original Message-
From: [EMAIL PROTECTED]
[mailto:[EMAIL PROTECTED] On Behalf Of [EMAIL PROTECTED]
Sent: Wednesday, October 10, 2007 1:17 PM
To: time-nuts@febo.com
Subject: Re: [time-nuts] Improving the stability of crystal
oscillators
-nuts@febo.com
Subject: Re: [time-nuts] Improving the stability of crystal
oscillators
In a message dated 10/10/2007 11:13:21 Pacific Daylight Time,
[EMAIL PROTECTED]
writes:
We first built a small proportional heater circuit that we
could shove
in next to the crystal, and that worked OK
Neville Michie wrote:
I have made several ovens for oscillators over the years.
The recipe is:
get a piece of aluminium big enough to contain the oscillator,
voltage regulator and first stage amplifier.
With a mill remove the shapes of each component.
Bolt a large power transistor, large
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