EK
Erik Kaashoek
Tue, Nov 9, 2021 5:26 PM
As far as I understood the ADEV at a Tau of 1 second is a statement
about the amount of variation to be expected over a one second interval.
It would be nice if we would be able to measure a frequency in an
infinite short interval but any frequency measurement takes time.
What if the frequency counter does a complete measurement of a frequency
source every second and all the variation within that second is hidden
because of the "integration" that happens over the second?
This is specially the case with continuous time-stamping counters.
They can provide a precise number by applying statistical methods on
many measurements done during one second but they can not provide
information exactly at the end of a second.
Is this kind of statistical measurement over a period of a second still
valid for determining the ADEV at the Tau of one second of a frequency
source?
Or should there be a correction factor depending on the method used in
the frequency counter?
I tried to read some scientific studies on this subject but I am not
smart enough to understand.
Hope one of you can provide some information.
Erik.
As far as I understood the ADEV at a Tau of 1 second is a statement
about the amount of variation to be expected over a one second interval.
It would be nice if we would be able to measure a frequency in an
infinite short interval but any frequency measurement takes time.
What if the frequency counter does a complete measurement of a frequency
source every second and all the variation within that second is hidden
because of the "integration" that happens over the second?
This is specially the case with continuous time-stamping counters.
They can provide a precise number by applying statistical methods on
many measurements done during one second but they can not provide
information exactly at the end of a second.
Is this kind of statistical measurement over a period of a second still
valid for determining the ADEV at the Tau of one second of a frequency
source?
Or should there be a correction factor depending on the method used in
the frequency counter?
I tried to read some scientific studies on this subject but I am not
smart enough to understand.
Hope one of you can provide some information.
Erik.
BK
Bob kb8tq
Tue, Nov 9, 2021 9:21 PM
Hi
The simple answer is that there are no shortcuts allowed if you are after a proper
ADEV. You take the (single) phase samples at the specified tau and push them into
the math. Anything else you do, will reduce the noise and thus compromise the noise
measuring properties of the approach.
Bob
On Nov 9, 2021, at 12:26 PM, Erik Kaashoek erik@kaashoek.com wrote:
As far as I understood the ADEV at a Tau of 1 second is a statement about the amount of variation to be expected over a one second interval.
It would be nice if we would be able to measure a frequency in an infinite short interval but any frequency measurement takes time.
What if the frequency counter does a complete measurement of a frequency source every second and all the variation within that second is hidden because of the "integration" that happens over the second?
This is specially the case with continuous time-stamping counters.
They can provide a precise number by applying statistical methods on many measurements done during one second but they can not provide information exactly at the end of a second.
Is this kind of statistical measurement over a period of a second still valid for determining the ADEV at the Tau of one second of a frequency source?
Or should there be a correction factor depending on the method used in the frequency counter?
I tried to read some scientific studies on this subject but I am not smart enough to understand.
Hope one of you can provide some information.
Erik.
time-nuts mailing list -- time-nuts@lists.febo.com -- To unsubscribe send an email to time-nuts-leave@lists.febo.com
To unsubscribe, go to and follow the instructions there.
Hi
The simple answer is that there are no shortcuts allowed if you are after a proper
ADEV. You take the (single) phase samples at the specified tau and push them into
the math. Anything else you do, will reduce the noise and thus compromise the noise
measuring properties of the approach.
Bob
> On Nov 9, 2021, at 12:26 PM, Erik Kaashoek <erik@kaashoek.com> wrote:
>
> As far as I understood the ADEV at a Tau of 1 second is a statement about the amount of variation to be expected over a one second interval.
> It would be nice if we would be able to measure a frequency in an infinite short interval but any frequency measurement takes time.
> What if the frequency counter does a complete measurement of a frequency source every second and all the variation within that second is hidden because of the "integration" that happens over the second?
> This is specially the case with continuous time-stamping counters.
> They can provide a precise number by applying statistical methods on many measurements done during one second but they can not provide information exactly at the end of a second.
> Is this kind of statistical measurement over a period of a second still valid for determining the ADEV at the Tau of one second of a frequency source?
> Or should there be a correction factor depending on the method used in the frequency counter?
> I tried to read some scientific studies on this subject but I am not smart enough to understand.
> Hope one of you can provide some information.
> Erik.
> _______________________________________________
> time-nuts mailing list -- time-nuts@lists.febo.com -- To unsubscribe send an email to time-nuts-leave@lists.febo.com
> To unsubscribe, go to and follow the instructions there.
BK
Bob kb8tq
Tue, Nov 9, 2021 10:10 PM
On Nov 9, 2021, at 12:26 PM, Erik Kaashoek erik@kaashoek.com wrote:
As far as I understood the ADEV at a Tau of 1 second is a statement about the amount of variation to be expected over a one second interval.
It would be nice if we would be able to measure a frequency in an infinite short interval but any frequency measurement takes time.
What if the frequency counter does a complete measurement of a frequency source every second and all the variation within that second is hidden because of the "integration" that happens over the second?
This is specially the case with continuous time-stamping counters.
They can provide a precise number by applying statistical methods on many measurements done during one second but they can not provide information exactly at the end of a second.
Is this kind of statistical measurement over a period of a second still valid for determining the ADEV at the Tau of one second of a frequency source?
Or should there be a correction factor depending on the method used in the frequency counter?
I tried to read some scientific studies on this subject but I am not smart enough to understand.
Hope one of you can provide some information.
Erik.
time-nuts mailing list -- time-nuts@lists.febo.com -- To unsubscribe send an email to time-nuts-leave@lists.febo.com
To unsubscribe, go to and follow the instructions there.
> On Nov 9, 2021, at 12:26 PM, Erik Kaashoek <erik@kaashoek.com> wrote:
>
> As far as I understood the ADEV at a Tau of 1 second is a statement about the amount of variation to be expected over a one second interval.
> It would be nice if we would be able to measure a frequency in an infinite short interval but any frequency measurement takes time.
> What if the frequency counter does a complete measurement of a frequency source every second and all the variation within that second is hidden because of the "integration" that happens over the second?
> This is specially the case with continuous time-stamping counters.
> They can provide a precise number by applying statistical methods on many measurements done during one second but they can not provide information exactly at the end of a second.
> Is this kind of statistical measurement over a period of a second still valid for determining the ADEV at the Tau of one second of a frequency source?
> Or should there be a correction factor depending on the method used in the frequency counter?
> I tried to read some scientific studies on this subject but I am not smart enough to understand.
> Hope one of you can provide some information.
> Erik.
> _______________________________________________
> time-nuts mailing list -- time-nuts@lists.febo.com -- To unsubscribe send an email to time-nuts-leave@lists.febo.com
> To unsubscribe, go to and follow the instructions there.
MD
Magnus Danielson
Tue, Nov 9, 2021 10:29 PM
Hi Erik,
On 2021-11-09 18:26, Erik Kaashoek wrote:
As far as I understood the ADEV at a Tau of 1 second is a statement
about the amount of variation to be expected over a one second interval.
Rather, the variation of readings of a frequency estimation done over a
span over 1 second.
It would be nice if we would be able to measure a frequency in an
infinite short interval but any frequency measurement takes time.
Turn out that basic white noise and systematic noise will limit our
frequency resolution to form a 1/tau limit slope, so infinite short
interval will bury it well into that noise whatever we do.
What if the frequency counter does a complete measurement of a
frequency source every second and all the variation within that second
is hidden because of the "integration" that happens over the second?
That is what happens, but that is not what the ADEV is about, it's about
the variations of these measures as we look for a bunch of them. So if
we now have say 1000 of these frequency estimates, how much variations
in these can be contributed to the random noise of the source, and to
analyse that, we need at least a tool like ADEV since standard deviation
will not even converge for white and flicker phase noise modulation.
What ADEV actually aims to do is to provide a low-frequency spectroscopy
method at a time when time-interval counters was about the only tool at
hand, and even those where very rare. We now have a much wider palette
of tools, but ADEV is relevant for how we measure frequency stability
and a few other applications.
This is specially the case with continuous time-stamping counters.
They can provide a precise number by applying statistical methods on
many measurements done during one second but they can not provide
information exactly at the end of a second.
Is this kind of statistical measurement over a period of a second
still valid for determining the ADEV at the Tau of one second of a
frequency source?
Not for ADEV, but if you use averaging counter you get the result of
MDEV and for linear regression / least square counter you get the
response of PDEV. That is the result of various statistical measures and
then applying the ADEV processing on these frequency estimates. The
upcoming IEEE Std 1139 revision, which is in approval process now
include language to reflect that.
Or should there be a correction factor depending on the method used in
the frequency counter?
Yes, you then need to use the appropriate bias function for ADEV/MDEV
and ADEV/PDEV to convert between these scales. Knowing the response of
ADEV, MDEV and PDEV for a particular noise-type which is dominant at the
tau of interest, you can readily convert between them by forming the
bias functions.
You may find NIST SP-1065 a useful and handy tool, even if it does not
cover the more recent work such as PDEV.
https://www.nist.gov/publications/handbook-frequency-stability-analysis
I tried to read some scientific studies on this subject but I am not
smart enough to understand.
Hope one of you can provide some information.
It is scattered over a large number of articles, and quite a lot of
folks get confused. Hopefully the updated IEEE Std 1139 will be of aid
to you. It also has lots of useful references.
Cheers,
Magnus
Hi Erik,
On 2021-11-09 18:26, Erik Kaashoek wrote:
> As far as I understood the ADEV at a Tau of 1 second is a statement
> about the amount of variation to be expected over a one second interval.
Rather, the variation of readings of a frequency estimation done over a
span over 1 second.
> It would be nice if we would be able to measure a frequency in an
> infinite short interval but any frequency measurement takes time.
Turn out that basic white noise and systematic noise will limit our
frequency resolution to form a 1/tau limit slope, so infinite short
interval will bury it well into that noise whatever we do.
> What if the frequency counter does a complete measurement of a
> frequency source every second and all the variation within that second
> is hidden because of the "integration" that happens over the second?
That is what happens, but that is not what the ADEV is about, it's about
the variations of these measures as we look for a bunch of them. So if
we now have say 1000 of these frequency estimates, how much variations
in these can be contributed to the random noise of the source, and to
analyse that, we need at least a tool like ADEV since standard deviation
will not even converge for white and flicker phase noise modulation.
What ADEV actually aims to do is to provide a low-frequency spectroscopy
method at a time when time-interval counters was about the only tool at
hand, and even those where very rare. We now have a much wider palette
of tools, but ADEV is relevant for how we measure frequency stability
and a few other applications.
> This is specially the case with continuous time-stamping counters.
> They can provide a precise number by applying statistical methods on
> many measurements done during one second but they can not provide
> information exactly at the end of a second.
> Is this kind of statistical measurement over a period of a second
> still valid for determining the ADEV at the Tau of one second of a
> frequency source?
Not for ADEV, but if you use averaging counter you get the result of
MDEV and for linear regression / least square counter you get the
response of PDEV. That is the result of various statistical measures and
then applying the ADEV processing on these frequency estimates. The
upcoming IEEE Std 1139 revision, which is in approval process now
include language to reflect that.
> Or should there be a correction factor depending on the method used in
> the frequency counter?
Yes, you then need to use the appropriate bias function for ADEV/MDEV
and ADEV/PDEV to convert between these scales. Knowing the response of
ADEV, MDEV and PDEV for a particular noise-type which is dominant at the
tau of interest, you can readily convert between them by forming the
bias functions.
You may find NIST SP-1065 a useful and handy tool, even if it does not
cover the more recent work such as PDEV.
https://www.nist.gov/publications/handbook-frequency-stability-analysis
> I tried to read some scientific studies on this subject but I am not
> smart enough to understand.
> Hope one of you can provide some information.
It is scattered over a large number of articles, and quite a lot of
folks get confused. Hopefully the updated IEEE Std 1139 will be of aid
to you. It also has lots of useful references.
Cheers,
Magnus
R(
Richard (Rick) Karlquist
Wed, Nov 10, 2021 12:53 AM
Let me just mention that when I worked at the HP Santa Clara
Division counters section, they came out with a "feature"
that they called "continuous count". However, it was limited
to something like 3 MHz. So a 100 MHz counter would only
continuously count signals below 3 MHz.
So you need to verify for what bandwidth your specific counter
model is truly doing continuous count.
Rick N6RK
On 11/9/2021 2:29 PM, Magnus Danielson via time-nuts wrote:
Hi Erik,
On 2021-11-09 18:26, Erik Kaashoek wrote:
As far as I understood the ADEV at a Tau of 1 second is a statement
about the amount of variation to be expected over a one second interval.
Rather, the variation of readings of a frequency estimation done over a
span over 1 second.
It would be nice if we would be able to measure a frequency in an
infinite short interval but any frequency measurement takes time.
Turn out that basic white noise and systematic noise will limit our
frequency resolution to form a 1/tau limit slope, so infinite short
interval will bury it well into that noise whatever we do.
What if the frequency counter does a complete measurement of a
frequency source every second and all the variation within that second
is hidden because of the "integration" that happens over the second?
That is what happens, but that is not what the ADEV is about, it's about
the variations of these measures as we look for a bunch of them. So if
we now have say 1000 of these frequency estimates, how much variations
in these can be contributed to the random noise of the source, and to
analyse that, we need at least a tool like ADEV since standard deviation
will not even converge for white and flicker phase noise modulation.
What ADEV actually aims to do is to provide a low-frequency spectroscopy
method at a time when time-interval counters was about the only tool at
hand, and even those where very rare. We now have a much wider palette
of tools, but ADEV is relevant for how we measure frequency stability
and a few other applications.
This is specially the case with continuous time-stamping counters.
They can provide a precise number by applying statistical methods on
many measurements done during one second but they can not provide
information exactly at the end of a second.
Is this kind of statistical measurement over a period of a second
still valid for determining the ADEV at the Tau of one second of a
frequency source?
Not for ADEV, but if you use averaging counter you get the result of
MDEV and for linear regression / least square counter you get the
response of PDEV. That is the result of various statistical measures and
then applying the ADEV processing on these frequency estimates. The
upcoming IEEE Std 1139 revision, which is in approval process now
include language to reflect that.
Or should there be a correction factor depending on the method used in
the frequency counter?
Yes, you then need to use the appropriate bias function for ADEV/MDEV
and ADEV/PDEV to convert between these scales. Knowing the response of
ADEV, MDEV and PDEV for a particular noise-type which is dominant at the
tau of interest, you can readily convert between them by forming the
bias functions.
You may find NIST SP-1065 a useful and handy tool, even if it does not
cover the more recent work such as PDEV.
https://www.nist.gov/publications/handbook-frequency-stability-analysis
I tried to read some scientific studies on this subject but I am not
smart enough to understand.
Hope one of you can provide some information.
It is scattered over a large number of articles, and quite a lot of
folks get confused. Hopefully the updated IEEE Std 1139 will be of aid
to you. It also has lots of useful references.
Cheers,
Magnus
time-nuts mailing list -- time-nuts@lists.febo.com -- To unsubscribe
send an email to time-nuts-leave@lists.febo.com
To unsubscribe, go to and follow the instructions there.
Let me just mention that when I worked at the HP Santa Clara
Division counters section, they came out with a "feature"
that they called "continuous count". However, it was limited
to something like 3 MHz. So a 100 MHz counter would only
continuously count signals below 3 MHz.
So you need to verify for what bandwidth your specific counter
model is truly doing continuous count.
Rick N6RK
On 11/9/2021 2:29 PM, Magnus Danielson via time-nuts wrote:
> Hi Erik,
>
> On 2021-11-09 18:26, Erik Kaashoek wrote:
>> As far as I understood the ADEV at a Tau of 1 second is a statement
>> about the amount of variation to be expected over a one second interval.
> Rather, the variation of readings of a frequency estimation done over a
> span over 1 second.
>> It would be nice if we would be able to measure a frequency in an
>> infinite short interval but any frequency measurement takes time.
> Turn out that basic white noise and systematic noise will limit our
> frequency resolution to form a 1/tau limit slope, so infinite short
> interval will bury it well into that noise whatever we do.
>> What if the frequency counter does a complete measurement of a
>> frequency source every second and all the variation within that second
>> is hidden because of the "integration" that happens over the second?
>
> That is what happens, but that is not what the ADEV is about, it's about
> the variations of these measures as we look for a bunch of them. So if
> we now have say 1000 of these frequency estimates, how much variations
> in these can be contributed to the random noise of the source, and to
> analyse that, we need at least a tool like ADEV since standard deviation
> will not even converge for white and flicker phase noise modulation.
>
> What ADEV actually aims to do is to provide a low-frequency spectroscopy
> method at a time when time-interval counters was about the only tool at
> hand, and even those where very rare. We now have a much wider palette
> of tools, but ADEV is relevant for how we measure frequency stability
> and a few other applications.
>
>> This is specially the case with continuous time-stamping counters.
>> They can provide a precise number by applying statistical methods on
>> many measurements done during one second but they can not provide
>> information exactly at the end of a second.
>> Is this kind of statistical measurement over a period of a second
>> still valid for determining the ADEV at the Tau of one second of a
>> frequency source?
> Not for ADEV, but if you use averaging counter you get the result of
> MDEV and for linear regression / least square counter you get the
> response of PDEV. That is the result of various statistical measures and
> then applying the ADEV processing on these frequency estimates. The
> upcoming IEEE Std 1139 revision, which is in approval process now
> include language to reflect that.
>> Or should there be a correction factor depending on the method used in
>> the frequency counter?
>
> Yes, you then need to use the appropriate bias function for ADEV/MDEV
> and ADEV/PDEV to convert between these scales. Knowing the response of
> ADEV, MDEV and PDEV for a particular noise-type which is dominant at the
> tau of interest, you can readily convert between them by forming the
> bias functions.
>
> You may find NIST SP-1065 a useful and handy tool, even if it does not
> cover the more recent work such as PDEV.
>
> https://www.nist.gov/publications/handbook-frequency-stability-analysis
>
>> I tried to read some scientific studies on this subject but I am not
>> smart enough to understand.
>> Hope one of you can provide some information.
>
> It is scattered over a large number of articles, and quite a lot of
> folks get confused. Hopefully the updated IEEE Std 1139 will be of aid
> to you. It also has lots of useful references.
>
> Cheers,
> Magnus
> _______________________________________________
> time-nuts mailing list -- time-nuts@lists.febo.com -- To unsubscribe
> send an email to time-nuts-leave@lists.febo.com
> To unsubscribe, go to and follow the instructions there.
>
MD
Magnus Danielson
Wed, Nov 10, 2021 8:10 AM
Rick,
"continuous count" as in counting/time-stamping each individual cycle
forms a sample-rate limit. However, this is not what is meant with
continuous conting today, as that is that you have a continuous
time-stamping for some time-base. In that some number of counted cycle
(+/- 1) occurs between each time-stamp. Unless one attempts to use
time-base very near the maximum sample rate per second, it cease to be a
practical concern as one does not want to miss samples.
I have a counter that can time-stamp at 10 MSa/s and 13.333 MSa/s
depending on mode. I extremely rarely use that even close to the
extreme, as continuous counting I normally need is maybe up to 100 Sa/s.
Cheers,
Magnus
On 2021-11-10 01:53, Richard (Rick) Karlquist wrote:
Let me just mention that when I worked at the HP Santa Clara
Division counters section, they came out with a "feature"
that they called "continuous count". However, it was limited
to something like 3 MHz. So a 100 MHz counter would only
continuously count signals below 3 MHz.
So you need to verify for what bandwidth your specific counter
model is truly doing continuous count.
Rick N6RK
On 11/9/2021 2:29 PM, Magnus Danielson via time-nuts wrote:
Hi Erik,
On 2021-11-09 18:26, Erik Kaashoek wrote:
As far as I understood the ADEV at a Tau of 1 second is a statement
about the amount of variation to be expected over a one second
interval.
Rather, the variation of readings of a frequency estimation done over
a span over 1 second.
It would be nice if we would be able to measure a frequency in an
infinite short interval but any frequency measurement takes time.
Turn out that basic white noise and systematic noise will limit our
frequency resolution to form a 1/tau limit slope, so infinite short
interval will bury it well into that noise whatever we do.
What if the frequency counter does a complete measurement of a
frequency source every second and all the variation within that
second is hidden because of the "integration" that happens over the
second?
That is what happens, but that is not what the ADEV is about, it's
about the variations of these measures as we look for a bunch of
them. So if we now have say 1000 of these frequency estimates, how
much variations in these can be contributed to the random noise of
the source, and to analyse that, we need at least a tool like ADEV
since standard deviation will not even converge for white and flicker
phase noise modulation.
What ADEV actually aims to do is to provide a low-frequency
spectroscopy method at a time when time-interval counters was about
the only tool at hand, and even those where very rare. We now have a
much wider palette of tools, but ADEV is relevant for how we measure
frequency stability and a few other applications.
This is specially the case with continuous time-stamping counters.
They can provide a precise number by applying statistical methods on
many measurements done during one second but they can not provide
information exactly at the end of a second.
Is this kind of statistical measurement over a period of a second
still valid for determining the ADEV at the Tau of one second of a
frequency source?
Not for ADEV, but if you use averaging counter you get the result of
MDEV and for linear regression / least square counter you get the
response of PDEV. That is the result of various statistical measures
and then applying the ADEV processing on these frequency estimates.
The upcoming IEEE Std 1139 revision, which is in approval process now
include language to reflect that.
Or should there be a correction factor depending on the method used
in the frequency counter?
Yes, you then need to use the appropriate bias function for ADEV/MDEV
and ADEV/PDEV to convert between these scales. Knowing the response
of ADEV, MDEV and PDEV for a particular noise-type which is dominant
at the tau of interest, you can readily convert between them by
forming the bias functions.
You may find NIST SP-1065 a useful and handy tool, even if it does
not cover the more recent work such as PDEV.
https://www.nist.gov/publications/handbook-frequency-stability-analysis
I tried to read some scientific studies on this subject but I am not
smart enough to understand.
Hope one of you can provide some information.
It is scattered over a large number of articles, and quite a lot of
folks get confused. Hopefully the updated IEEE Std 1139 will be of
aid to you. It also has lots of useful references.
Cheers,
Magnus
time-nuts mailing list -- time-nuts@lists.febo.com -- To unsubscribe
send an email to time-nuts-leave@lists.febo.com
To unsubscribe, go to and follow the instructions there.
Rick,
"continuous count" as in counting/time-stamping each individual cycle
forms a sample-rate limit. However, this is not what is meant with
continuous conting today, as that is that you have a continuous
time-stamping for some time-base. In that some number of counted cycle
(+/- 1) occurs between each time-stamp. Unless one attempts to use
time-base very near the maximum sample rate per second, it cease to be a
practical concern as one does not want to miss samples.
I have a counter that can time-stamp at 10 MSa/s and 13.333 MSa/s
depending on mode. I extremely rarely use that even close to the
extreme, as continuous counting I normally need is maybe up to 100 Sa/s.
Cheers,
Magnus
On 2021-11-10 01:53, Richard (Rick) Karlquist wrote:
> Let me just mention that when I worked at the HP Santa Clara
> Division counters section, they came out with a "feature"
> that they called "continuous count". However, it was limited
> to something like 3 MHz. So a 100 MHz counter would only
> continuously count signals below 3 MHz.
>
> So you need to verify for what bandwidth your specific counter
> model is truly doing continuous count.
>
> Rick N6RK
>
> On 11/9/2021 2:29 PM, Magnus Danielson via time-nuts wrote:
>> Hi Erik,
>>
>> On 2021-11-09 18:26, Erik Kaashoek wrote:
>>> As far as I understood the ADEV at a Tau of 1 second is a statement
>>> about the amount of variation to be expected over a one second
>>> interval.
>> Rather, the variation of readings of a frequency estimation done over
>> a span over 1 second.
>>> It would be nice if we would be able to measure a frequency in an
>>> infinite short interval but any frequency measurement takes time.
>> Turn out that basic white noise and systematic noise will limit our
>> frequency resolution to form a 1/tau limit slope, so infinite short
>> interval will bury it well into that noise whatever we do.
>>> What if the frequency counter does a complete measurement of a
>>> frequency source every second and all the variation within that
>>> second is hidden because of the "integration" that happens over the
>>> second?
>>
>> That is what happens, but that is not what the ADEV is about, it's
>> about the variations of these measures as we look for a bunch of
>> them. So if we now have say 1000 of these frequency estimates, how
>> much variations in these can be contributed to the random noise of
>> the source, and to analyse that, we need at least a tool like ADEV
>> since standard deviation will not even converge for white and flicker
>> phase noise modulation.
>>
>> What ADEV actually aims to do is to provide a low-frequency
>> spectroscopy method at a time when time-interval counters was about
>> the only tool at hand, and even those where very rare. We now have a
>> much wider palette of tools, but ADEV is relevant for how we measure
>> frequency stability and a few other applications.
>>
>>> This is specially the case with continuous time-stamping counters.
>>> They can provide a precise number by applying statistical methods on
>>> many measurements done during one second but they can not provide
>>> information exactly at the end of a second.
>>> Is this kind of statistical measurement over a period of a second
>>> still valid for determining the ADEV at the Tau of one second of a
>>> frequency source?
>> Not for ADEV, but if you use averaging counter you get the result of
>> MDEV and for linear regression / least square counter you get the
>> response of PDEV. That is the result of various statistical measures
>> and then applying the ADEV processing on these frequency estimates.
>> The upcoming IEEE Std 1139 revision, which is in approval process now
>> include language to reflect that.
>>> Or should there be a correction factor depending on the method used
>>> in the frequency counter?
>>
>> Yes, you then need to use the appropriate bias function for ADEV/MDEV
>> and ADEV/PDEV to convert between these scales. Knowing the response
>> of ADEV, MDEV and PDEV for a particular noise-type which is dominant
>> at the tau of interest, you can readily convert between them by
>> forming the bias functions.
>>
>> You may find NIST SP-1065 a useful and handy tool, even if it does
>> not cover the more recent work such as PDEV.
>>
>> https://www.nist.gov/publications/handbook-frequency-stability-analysis
>>
>>> I tried to read some scientific studies on this subject but I am not
>>> smart enough to understand.
>>> Hope one of you can provide some information.
>>
>> It is scattered over a large number of articles, and quite a lot of
>> folks get confused. Hopefully the updated IEEE Std 1139 will be of
>> aid to you. It also has lots of useful references.
>>
>> Cheers,
>> Magnus
>> _______________________________________________
>> time-nuts mailing list -- time-nuts@lists.febo.com -- To unsubscribe
>> send an email to time-nuts-leave@lists.febo.com
>> To unsubscribe, go to and follow the instructions there.
>>
R(
Richard (Rick) Karlquist
Wed, Nov 10, 2021 10:40 PM
I am looking for help choosing a potting compound that
has the following properties:
- Good for 5,000VAC @ 1 MHz
- Low RF losses.
- Low permittivity is preferred
- Low tempco of permittivity is a want.
- Something I can implement in my home shop
without access to a vacuum pump etc. is a want.
Thanks in advance
Rick Karlquist N6RK
I am looking for help choosing a potting compound that
has the following properties:
1. Good for 5,000VAC @ 1 MHz
2. Low RF losses.
3. Low permittivity is preferred
4. Low tempco of permittivity is a want.
5. Something I can implement in my home shop
without access to a vacuum pump etc. is a want.
Thanks in advance
Rick Karlquist N6RK
LJ
Lux, Jim
Thu, Nov 11, 2021 12:32 AM
On 11/10/21 2:40 PM, Richard (Rick) Karlquist wrote:
I am looking for help choosing a potting compound that
has the following properties:
1. Good for 5,000VAC @ 1 MHz
2. Low RF losses.
3. Low permittivity is preferred
4. Low tempco of permittivity is a want.
5. Something I can implement in my home shop
without access to a vacuum pump etc. is a want.
What about curing? Is temperature cure (put it in an oven) ok? or do you
need room temp cure?
Silicones are usually pretty good, RF wise. But you need to check the
filler and exact composition.
I found a two component silicone that has epsilon 2.5 used for RF
potting, 15kV/mm breakdown.
https://vitrochem.com/wordpress/wp-content/uploads/2020/10/Two-Component-Condensation-Silicone.pdf
they say nothing about the dissipation.
Aha. RTV12 from Momentive - clear - epsilon 3.0, tan d (at 1kHz) is
0.001, 400 V/mil - This stuff is pretty common, but I can't find any
higher frequency permittivity info, which is odd. Someone somewhere
probably built something and measured it.
Diallyl Pthalate is what they use in connectors - it's a thermosetting
resin with good electrical properties.
https://www.cosmicplastics.com/products/dap/
Picking the first one in the list 224 DAP - 360 V/mil, so for your 5kV,
you'd need ~14 mils. (most plastics are in this range)
Epsilon is kind of high 3.5, tan D is 0.01? Is that good enough for you
dissipation wise? There's lots of kinds with various fillers.
A common way to reduce epsilon and tan d is to mix in microspheres.
Some epoxies are also good. Rogers not only makes laminates for
circuitboards they also produce the epoxy from which they are made
We use tons of arathane and solithane at JPL (both are urethanes), but I
don't know if we pot RF circuits in araldite. Huntsman makes the
"ara???" materials
https://huntsman-pimcore.equisolve-dev.com/Documents/US_2019_High_Performance_Components_Selector_Guide.pdf
one thing is that we store this stuff at -80C, but I don't know if
that's after mixing or if it's shipped that way (in dry ice).
masterbond.com -> give them a call or email
EP110F80-1 is a 2 part epoxy with e=2.69@1MHz, so it's probably
reasonably low loss.
On 11/10/21 2:40 PM, Richard (Rick) Karlquist wrote:
> I am looking for help choosing a potting compound that
> has the following properties:
>
> 1. Good for 5,000VAC @ 1 MHz
> 2. Low RF losses.
> 3. Low permittivity is preferred
> 4. Low tempco of permittivity is a want.
> 5. Something I can implement in my home shop
> without access to a vacuum pump etc. is a want.
What about curing? Is temperature cure (put it in an oven) ok? or do you
need room temp cure?
Silicones are usually pretty good, RF wise. But you need to check the
filler and exact composition.
I found a two component silicone that has epsilon 2.5 used for RF
potting, 15kV/mm breakdown.
https://vitrochem.com/wordpress/wp-content/uploads/2020/10/Two-Component-Condensation-Silicone.pdf
they say nothing about the dissipation.
Aha. RTV12 from Momentive - clear - epsilon 3.0, tan d (at 1kHz) is
0.001, 400 V/mil - This stuff is pretty common, but I can't find any
higher frequency permittivity info, which is odd. Someone somewhere
probably built something and measured it.
Diallyl Pthalate is what they use in connectors - it's a thermosetting
resin with good electrical properties.
https://www.cosmicplastics.com/products/dap/
Picking the first one in the list 224 DAP - 360 V/mil, so for your 5kV,
you'd need ~14 mils. (most plastics are in this range)
Epsilon is kind of high 3.5, tan D is 0.01? Is that good enough for you
dissipation wise? There's lots of kinds with various fillers.
A common way to reduce epsilon and tan d is to mix in microspheres.
Some epoxies are also good. Rogers not only makes laminates for
circuitboards they also produce the epoxy from which they are made
We use tons of arathane and solithane at JPL (both are urethanes), but I
don't know if we pot RF circuits in araldite. Huntsman makes the
"ara???" materials
https://huntsman-pimcore.equisolve-dev.com/Documents/US_2019_High_Performance_Components_Selector_Guide.pdf
one thing is that we store this stuff at -80C, but I don't know if
that's after mixing or if it's shipped that way (in dry ice).
masterbond.com -> give them a call or email
EP110F80-1 is a 2 part epoxy with e=2.69@1MHz, so it's probably
reasonably low loss.
BC
Brooke Clarke
Thu, Nov 11, 2021 12:37 AM
Hi Jim:
Be careful with RTVs. Some out gas acid that attacks metal, even gold plated metal. Guess how I know that.
--
Have Fun,
Brooke Clarke
https://www.PRC68.com
axioms:
- The extent to which you can fix or improve something will be limited by how well you understand how it works.
- Everybody, with no exceptions, holds false beliefs.
-------- Original Message --------
On 11/10/21 2:40 PM, Richard (Rick) Karlquist wrote:
I am looking for help choosing a potting compound that
has the following properties:
1. Good for 5,000VAC @ 1 MHz
2. Low RF losses.
3. Low permittivity is preferred
4. Low tempco of permittivity is a want.
5. Something I can implement in my home shop
without access to a vacuum pump etc. is a want.
What about curing? Is temperature cure (put it in an oven) ok? or do you need room temp cure?
Silicones are usually pretty good, RF wise. But you need to check the filler and exact composition.
I found a two component silicone that has epsilon 2.5 used for RF potting, 15kV/mm breakdown.
https://vitrochem.com/wordpress/wp-content/uploads/2020/10/Two-Component-Condensation-Silicone.pdf
they say nothing about the dissipation.
Aha. RTV12 from Momentive - clear - epsilon 3.0, tan d (at 1kHz) is 0.001, 400 V/mil - This stuff is pretty common,
but I can't find any higher frequency permittivity info, which is odd. Someone somewhere probably built something and
measured it.
Diallyl Pthalate is what they use in connectors - it's a thermosetting resin with good electrical properties.
https://www.cosmicplastics.com/products/dap/
Picking the first one in the list 224 DAP - 360 V/mil, so for your 5kV, you'd need ~14 mils. (most plastics are in
this range)
Epsilon is kind of high 3.5, tan D is 0.01? Is that good enough for you dissipation wise? There's lots of kinds with
various fillers.
A common way to reduce epsilon and tan d is to mix in microspheres.
Some epoxies are also good. Rogers not only makes laminates for circuitboards they also produce the epoxy from which
they are made
We use tons of arathane and solithane at JPL (both are urethanes), but I don't know if we pot RF circuits in araldite.
Huntsman makes the "ara???" materials
https://huntsman-pimcore.equisolve-dev.com/Documents/US_2019_High_Performance_Components_Selector_Guide.pdf
one thing is that we store this stuff at -80C, but I don't know if that's after mixing or if it's shipped that way (in
dry ice).
masterbond.com -> give them a call or email
EP110F80-1 is a 2 part epoxy with e=2.69@1MHz, so it's probably reasonably low loss.
time-nuts mailing list -- time-nuts@lists.febo.com -- To unsubscribe send an email to time-nuts-leave@lists.febo.com
To unsubscribe, go to and follow the instructions there.
Hi Jim:
Be careful with RTVs. Some out gas acid that attacks metal, even gold plated metal. Guess how I know that.
--
Have Fun,
Brooke Clarke
https://www.PRC68.com
axioms:
1. The extent to which you can fix or improve something will be limited by how well you understand how it works.
2. Everybody, with no exceptions, holds false beliefs.
-------- Original Message --------
> On 11/10/21 2:40 PM, Richard (Rick) Karlquist wrote:
>> I am looking for help choosing a potting compound that
>> has the following properties:
>>
>> 1. Good for 5,000VAC @ 1 MHz
>> 2. Low RF losses.
>> 3. Low permittivity is preferred
>> 4. Low tempco of permittivity is a want.
>> 5. Something I can implement in my home shop
>> without access to a vacuum pump etc. is a want.
>
> What about curing? Is temperature cure (put it in an oven) ok? or do you need room temp cure?
>
>
> Silicones are usually pretty good, RF wise. But you need to check the filler and exact composition.
>
> I found a two component silicone that has epsilon 2.5 used for RF potting, 15kV/mm breakdown.
>
> https://vitrochem.com/wordpress/wp-content/uploads/2020/10/Two-Component-Condensation-Silicone.pdf
>
> they say nothing about the dissipation.
>
>
> Aha. RTV12 from Momentive - clear - epsilon 3.0, tan d (at 1kHz) is 0.001, 400 V/mil - This stuff is pretty common,
> but I can't find any higher frequency permittivity info, which is odd. Someone somewhere probably built something and
> measured it.
>
>
> Diallyl Pthalate is what they use in connectors - it's a thermosetting resin with good electrical properties.
>
> https://www.cosmicplastics.com/products/dap/
>
> Picking the first one in the list 224 DAP - 360 V/mil, so for your 5kV, you'd need ~14 mils. (most plastics are in
> this range)
>
> Epsilon is kind of high 3.5, tan D is 0.01? Is that good enough for you dissipation wise? There's lots of kinds with
> various fillers.
>
> A common way to reduce epsilon and tan d is to mix in microspheres.
>
>
> Some epoxies are also good. Rogers not only makes laminates for circuitboards they also produce the epoxy from which
> they are made
>
>
> We use tons of arathane and solithane at JPL (both are urethanes), but I don't know if we pot RF circuits in araldite.
> Huntsman makes the "ara???" materials
>
> https://huntsman-pimcore.equisolve-dev.com/Documents/US_2019_High_Performance_Components_Selector_Guide.pdf
>
> one thing is that we store this stuff at -80C, but I don't know if that's after mixing or if it's shipped that way (in
> dry ice).
>
> masterbond.com -> give them a call or email
>
> EP110F80-1 is a 2 part epoxy with e=2.69@1MHz, so it's probably reasonably low loss.
> _______________________________________________
> time-nuts mailing list -- time-nuts@lists.febo.com -- To unsubscribe send an email to time-nuts-leave@lists.febo.com
> To unsubscribe, go to and follow the instructions there.
LJ
Lux, Jim
Thu, Nov 11, 2021 12:38 AM
On 11/10/21 4:37 PM, Brooke Clarke via time-nuts wrote:
Hi Jim:
Be careful with RTVs. Some out gas acid that attacks metal, even gold
plated metal. Guess how I know that.
Oh yes.. one definitely needs to read the data sheets.. RTV12 is 2
part. Most 2 part RTVs don't use acid. And the one part that cure in
an oven at 70C, likewise.
On 11/10/21 4:37 PM, Brooke Clarke via time-nuts wrote:
> Hi Jim:
>
> Be careful with RTVs. Some out gas acid that attacks metal, even gold
> plated metal. Guess how I know that.
>
Oh yes.. one definitely needs to read the data sheets.. RTV12 is 2
part. Most 2 part RTVs don't use acid. And the one part that cure in
an oven at 70C, likewise.
MF
Mike Feher
Thu, Nov 11, 2021 1:09 AM
I too had the same experience Brooke. Back in the late 70's I built a TVRO station and saved up enough money for two GaAs FETs for an LNA. Used RTV to seal it. Sadly it died. Upon taking it apart to troubleshoot I found just about everything was green. 73 - Mike
Mike B. Feher, N4FS
89 Arnold Blvd.
Howell NJ 07731
848-245-9115
-----Original Message-----
From: Brooke Clarke via time-nuts time-nuts@lists.febo.com
Sent: Wednesday, November 10, 2021 7:37 PM
To: Discussion of precise time and frequency measurement time-nuts@lists.febo.com
Cc: Brooke Clarke brooke@pacific.net
Subject: [time-nuts] Re: Potting compound advice needed
Hi Jim:
Be careful with RTVs. Some out gas acid that attacks metal, even gold plated metal. Guess how I know that.
--
Have Fun,
Brooke Clarke
https://www.PRC68.com
axioms:
- The extent to which you can fix or improve something will be limited by how well you understand how it works.
- Everybody, with no exceptions, holds false beliefs.
I too had the same experience Brooke. Back in the late 70's I built a TVRO station and saved up enough money for two GaAs FETs for an LNA. Used RTV to seal it. Sadly it died. Upon taking it apart to troubleshoot I found just about everything was green. 73 - Mike
Mike B. Feher, N4FS
89 Arnold Blvd.
Howell NJ 07731
848-245-9115
-----Original Message-----
From: Brooke Clarke via time-nuts <time-nuts@lists.febo.com>
Sent: Wednesday, November 10, 2021 7:37 PM
To: Discussion of precise time and frequency measurement <time-nuts@lists.febo.com>
Cc: Brooke Clarke <brooke@pacific.net>
Subject: [time-nuts] Re: Potting compound advice needed
Hi Jim:
Be careful with RTVs. Some out gas acid that attacks metal, even gold plated metal. Guess how I know that.
--
Have Fun,
Brooke Clarke
https://www.PRC68.com
axioms:
1. The extent to which you can fix or improve something will be limited by how well you understand how it works.
2. Everybody, with no exceptions, holds false beliefs.
GH
Gerhard Hoffmann
Thu, Nov 11, 2021 1:31 AM
A customer of mine uses Solitane, another one Mupsil.
I just wrote down the names in case I might need it.
Probably more for coating boards in space apps, no idea
if it fits.
Am 10.11.21 um 23:40 schrieb Richard (Rick) Karlquist:
I am looking for help choosing a potting compound that
has the following properties:
A customer of mine uses Solitane, another one Mupsil.
I just wrote down the names in case I might need it.
Probably more for coating boards in space apps, no idea
if it fits.
Am 10.11.21 um 23:40 schrieb Richard (Rick) Karlquist:
> I am looking for help choosing a potting compound that
> has the following properties:
LJ
Lux, Jim
Thu, Nov 11, 2021 4:56 AM
On 11/10/21 5:31 PM, Gerhard Hoffmann wrote:
A customer of mine uses Solitane, another one Mupsil.
I just wrote down the names in case I might need it.
Probably more for coating boards in space apps, no idea
if it fits.
Am 10.11.21 um 23:40 schrieb Richard (Rick) Karlquist:
I am looking for help choosing a potting compound that
has the following properties:
Yeah, the solithane (that's the name we use) is more used to repair
conformal coatings, stake fasteners, stick wires down to the board, glue
components to the board so it will survive vibe (think tall skinny
things, with the vibe in the plane of the board). Fairly fluid, cures
fairly quickly, low outgassing, and most important for space - someone
else used it and it worked without causing a disaster. There probably
is a potting version of it, and I'll ask one of the M&P folks at work
tomorrow what they think about Rick's need.
I've not heard of Mupsil, but we use a lot of Nusil - silicone
elastomers, often with alumina particles in it, as a thermal bonding
material. Say you've got a box with a fairly flat surface that you want
to clamp to another fairly flat surface. The problem is that tightening
the fasteners deforms both surfaces (unless you've got a zillion of
them) so the thermal contact area is just around the fastener, and there
is a perhaps a gap everywhere else. Spaceflight people hate "perhaps" so
they say, ok, put a thermal gasket in there (hey, many of us have used a
mica washer and silicone grease between part and heat sink, right?).
You can get elastomeric thermal gaskets from Chomerics and similar
companies, but they actually have the same problem with clamping force.
You tighten the fasteners, but to get the required clamping force over
the WHOLE gasket, you need a lot of fasteners, or a lot of force, and
you're back to the deformation problem.
So the answer is "thermally conductive glue" - you slather a thin layer
on, tighten the fasteners, which then causes the alumina particles to
poke into the surfaces on both sides, and hey - good thermal
conductivity. Of course, if you need to take it off, you need to get in
there with a wire saw and that's "not fun".
I will say the nifty-est thermal connection was a sort of velvet made of
carbon fibers. Carbon fibers have very high thermal conductivity. You
bond that furry velvet to both surfaces, and when you put it together,
the fibers slide along each other and make good contact along their
length, and there's millions of them. You aren't depending on clamping
force - it's the springyness of the very stiff fibers that provides the
contact force, and as you can imagine, it can tolerate a lot of
misalignment and gaps.
The actual stuff was developed originally to make a very optically
absorbing black coating over wide bandwidths - all those fibers bounce
the light around. And as a laser load (instead of the proverbial stack
of razor blades. It was then was used to coat mannequin forms, for
displaying lingerie for Victoria's Secret, of all places, because it was
very rugged and didn't shed lint. There's a whole exotic trade secret
about how they make the velvet - there's some sort of electrostatic
technique to making the fibers stand on end while they're bonded, and
some other exotic trick to getting them all the same length, and so
forth. I kept trying to use it in space (it is so much easier than
glue, gaskets, or zillions of fasteners), but it never took -> 1) nobody
else had used it before and 2) everyone was worried about little
conductive fibers shedding and floating around into places they
shouldn't be. Again, in the space world, no matter how tedious and
painful, if it worked before, we can do it again. thermally conductive
glue may be a pain, but it's "known to work".
For those of you doing bolted joints.. thermal conductances are around
0.1 to 1 W/K -
You want to google a chapter called "Mountings and Interfaces" by Gluck
and Baturkin - It's in Spacecraft Thermal Control Handbook Volume 1. but
there's tons of copies floating around the web, and it's a great
handbook reference for "just what is the thermal resistance with a 4-40
screw through that TO-220 tab onto an aluminum chassis"
It's one of those references which everyone cites.
On 11/10/21 5:31 PM, Gerhard Hoffmann wrote:
> A customer of mine uses Solitane, another one Mupsil.
> I just wrote down the names in case I might need it.
> Probably more for coating boards in space apps, no idea
> if it fits.
>
>
> Am 10.11.21 um 23:40 schrieb Richard (Rick) Karlquist:
>> I am looking for help choosing a potting compound that
>> has the following properties:
> _
Yeah, the solithane (that's the name we use) is more used to repair
conformal coatings, stake fasteners, stick wires down to the board, glue
components to the board so it will survive vibe (think tall skinny
things, with the vibe in the plane of the board). Fairly fluid, cures
fairly quickly, low outgassing, and most important for space - someone
else used it and it worked without causing a disaster. There probably
is a potting version of it, and I'll ask one of the M&P folks at work
tomorrow what they think about Rick's need.
I've not heard of Mupsil, but we use a lot of Nusil - silicone
elastomers, often with alumina particles in it, as a thermal bonding
material. Say you've got a box with a fairly flat surface that you want
to clamp to another fairly flat surface. The problem is that tightening
the fasteners deforms both surfaces (unless you've got a zillion of
them) so the thermal contact area is just around the fastener, and there
is a perhaps a gap everywhere else. Spaceflight people hate "perhaps" so
they say, ok, put a thermal gasket in there (hey, many of us have used a
mica washer and silicone grease between part and heat sink, right?).
You can get elastomeric thermal gaskets from Chomerics and similar
companies, but they actually have the same problem with clamping force.
You tighten the fasteners, but to get the required clamping force over
the WHOLE gasket, you need a lot of fasteners, or a lot of force, and
you're back to the deformation problem.
So the answer is "thermally conductive glue" - you slather a thin layer
on, tighten the fasteners, which then causes the alumina particles to
poke into the surfaces on both sides, and hey - good thermal
conductivity. Of course, if you need to take it off, you need to get in
there with a wire saw and that's "not fun".
I will say the nifty-est thermal connection was a sort of velvet made of
carbon fibers. Carbon fibers have very high thermal conductivity. You
bond that furry velvet to both surfaces, and when you put it together,
the fibers slide along each other and make good contact along their
length, and there's millions of them. You aren't depending on clamping
force - it's the springyness of the very stiff fibers that provides the
contact force, and as you can imagine, it can tolerate a lot of
misalignment and gaps.
The actual stuff was developed originally to make a very optically
absorbing black coating over wide bandwidths - all those fibers bounce
the light around. And as a laser load (instead of the proverbial stack
of razor blades. It was then was used to coat mannequin forms, for
displaying lingerie for Victoria's Secret, of all places, because it was
very rugged and didn't shed lint. There's a whole exotic trade secret
about how they make the velvet - there's some sort of electrostatic
technique to making the fibers stand on end while they're bonded, and
some other exotic trick to getting them all the same length, and so
forth. I kept trying to use it in space (it is *so* much easier than
glue, gaskets, or zillions of fasteners), but it never took -> 1) nobody
else had used it before and 2) everyone was worried about little
conductive fibers shedding and floating around into places they
shouldn't be. Again, in the space world, no matter how tedious and
painful, if it worked before, we can do it again. thermally conductive
glue may be a pain, but it's "known to work".
For those of you doing bolted joints.. thermal conductances are around
0.1 to 1 W/K -
You want to google a chapter called "Mountings and Interfaces" by Gluck
and Baturkin - It's in Spacecraft Thermal Control Handbook Volume 1. but
there's tons of copies floating around the web, and it's a great
handbook reference for "just what is the thermal resistance with a 4-40
screw through that TO-220 tab onto an aluminum chassis"
It's one of those references which everyone cites.
JH
Javier Herrero
Thu, Nov 11, 2021 9:42 AM
Hello,
Probably Mupsil was a typo. Mapsil 213B is a silicone-based coating also
approved (at least by ESA) for space applications.
Regards,
Javier
On 11/11/21 5:56, Lux, Jim wrote:
On 11/10/21 5:31 PM, Gerhard Hoffmann wrote:
A customer of mine uses Solitane, another one Mupsil.
I just wrote down the names in case I might need it.
Probably more for coating boards in space apps, no idea
if it fits.
Am 10.11.21 um 23:40 schrieb Richard (Rick) Karlquist:
I am looking for help choosing a potting compound that
has the following properties:
Yeah, the solithane (that's the name we use) is more used to repair
conformal coatings, stake fasteners, stick wires down to the board,
glue components to the board so it will survive vibe (think tall
skinny things, with the vibe in the plane of the board). Fairly
fluid, cures fairly quickly, low outgassing, and most important for
space - someone else used it and it worked without causing a
disaster. There probably is a potting version of it, and I'll ask
one of the M&P folks at work tomorrow what they think about Rick's need.
I've not heard of Mupsil, but we use a lot of Nusil - silicone
elastomers, often with alumina particles in it, as a thermal bonding
material. Say you've got a box with a fairly flat surface that you
want to clamp to another fairly flat surface. The problem is that
tightening the fasteners deforms both surfaces (unless you've got a
zillion of them) so the thermal contact area is just around the
fastener, and there is a perhaps a gap everywhere else. Spaceflight
people hate "perhaps" so they say, ok, put a thermal gasket in there
(hey, many of us have used a mica washer and silicone grease between
part and heat sink, right?). You can get elastomeric thermal gaskets
from Chomerics and similar companies, but they actually have the same
problem with clamping force. You tighten the fasteners, but to get the
required clamping force over the WHOLE gasket, you need a lot of
fasteners, or a lot of force, and you're back to the deformation problem.
So the answer is "thermally conductive glue" - you slather a thin
layer on, tighten the fasteners, which then causes the alumina
particles to poke into the surfaces on both sides, and hey - good
thermal conductivity. Of course, if you need to take it off, you need
to get in there with a wire saw and that's "not fun".
I will say the nifty-est thermal connection was a sort of velvet made
of carbon fibers. Carbon fibers have very high thermal conductivity.
You bond that furry velvet to both surfaces, and when you put it
together, the fibers slide along each other and make good contact
along their length, and there's millions of them. You aren't depending
on clamping force - it's the springyness of the very stiff fibers that
provides the contact force, and as you can imagine, it can tolerate a
lot of misalignment and gaps.
The actual stuff was developed originally to make a very optically
absorbing black coating over wide bandwidths - all those fibers bounce
the light around. And as a laser load (instead of the proverbial stack
of razor blades. It was then was used to coat mannequin forms, for
displaying lingerie for Victoria's Secret, of all places, because it
was very rugged and didn't shed lint. There's a whole exotic trade
secret about how they make the velvet - there's some sort of
electrostatic technique to making the fibers stand on end while
they're bonded, and some other exotic trick to getting them all the
same length, and so forth. I kept trying to use it in space (it is
so much easier than glue, gaskets, or zillions of fasteners), but it
never took -> 1) nobody else had used it before and 2) everyone was
worried about little conductive fibers shedding and floating around
into places they shouldn't be. Again, in the space world, no matter
how tedious and painful, if it worked before, we can do it again.
thermally conductive glue may be a pain, but it's "known to work".
For those of you doing bolted joints.. thermal conductances are
around 0.1 to 1 W/K -
You want to google a chapter called "Mountings and Interfaces" by
Gluck and Baturkin - It's in Spacecraft Thermal Control Handbook
Volume 1. but there's tons of copies floating around the web, and it's
a great handbook reference for "just what is the thermal resistance
with a 4-40 screw through that TO-220 tab onto an aluminum chassis"
It's one of those references which everyone cites.
time-nuts mailing list -- time-nuts@lists.febo.com -- To unsubscribe
send an email to time-nuts-leave@lists.febo.com
To unsubscribe, go to and follow the instructions there.
Hello,
Probably Mupsil was a typo. Mapsil 213B is a silicone-based coating also
approved (at least by ESA) for space applications.
Regards,
Javier
On 11/11/21 5:56, Lux, Jim wrote:
> On 11/10/21 5:31 PM, Gerhard Hoffmann wrote:
>> A customer of mine uses Solitane, another one Mupsil.
>> I just wrote down the names in case I might need it.
>> Probably more for coating boards in space apps, no idea
>> if it fits.
>>
>>
>> Am 10.11.21 um 23:40 schrieb Richard (Rick) Karlquist:
>>> I am looking for help choosing a potting compound that
>>> has the following properties:
>> _
>
>
> Yeah, the solithane (that's the name we use) is more used to repair
> conformal coatings, stake fasteners, stick wires down to the board,
> glue components to the board so it will survive vibe (think tall
> skinny things, with the vibe in the plane of the board). Fairly
> fluid, cures fairly quickly, low outgassing, and most important for
> space - someone else used it and it worked without causing a
> disaster. There probably is a potting version of it, and I'll ask
> one of the M&P folks at work tomorrow what they think about Rick's need.
>
> I've not heard of Mupsil, but we use a lot of Nusil - silicone
> elastomers, often with alumina particles in it, as a thermal bonding
> material. Say you've got a box with a fairly flat surface that you
> want to clamp to another fairly flat surface. The problem is that
> tightening the fasteners deforms both surfaces (unless you've got a
> zillion of them) so the thermal contact area is just around the
> fastener, and there is a perhaps a gap everywhere else. Spaceflight
> people hate "perhaps" so they say, ok, put a thermal gasket in there
> (hey, many of us have used a mica washer and silicone grease between
> part and heat sink, right?). You can get elastomeric thermal gaskets
> from Chomerics and similar companies, but they actually have the same
> problem with clamping force. You tighten the fasteners, but to get the
> required clamping force over the WHOLE gasket, you need a lot of
> fasteners, or a lot of force, and you're back to the deformation problem.
>
> So the answer is "thermally conductive glue" - you slather a thin
> layer on, tighten the fasteners, which then causes the alumina
> particles to poke into the surfaces on both sides, and hey - good
> thermal conductivity. Of course, if you need to take it off, you need
> to get in there with a wire saw and that's "not fun".
>
> I will say the nifty-est thermal connection was a sort of velvet made
> of carbon fibers. Carbon fibers have very high thermal conductivity.
> You bond that furry velvet to both surfaces, and when you put it
> together, the fibers slide along each other and make good contact
> along their length, and there's millions of them. You aren't depending
> on clamping force - it's the springyness of the very stiff fibers that
> provides the contact force, and as you can imagine, it can tolerate a
> lot of misalignment and gaps.
>
> The actual stuff was developed originally to make a very optically
> absorbing black coating over wide bandwidths - all those fibers bounce
> the light around. And as a laser load (instead of the proverbial stack
> of razor blades. It was then was used to coat mannequin forms, for
> displaying lingerie for Victoria's Secret, of all places, because it
> was very rugged and didn't shed lint. There's a whole exotic trade
> secret about how they make the velvet - there's some sort of
> electrostatic technique to making the fibers stand on end while
> they're bonded, and some other exotic trick to getting them all the
> same length, and so forth. I kept trying to use it in space (it is
> *so* much easier than glue, gaskets, or zillions of fasteners), but it
> never took -> 1) nobody else had used it before and 2) everyone was
> worried about little conductive fibers shedding and floating around
> into places they shouldn't be. Again, in the space world, no matter
> how tedious and painful, if it worked before, we can do it again.
> thermally conductive glue may be a pain, but it's "known to work".
>
>
> For those of you doing bolted joints.. thermal conductances are
> around 0.1 to 1 W/K -
>
> You want to google a chapter called "Mountings and Interfaces" by
> Gluck and Baturkin - It's in Spacecraft Thermal Control Handbook
> Volume 1. but there's tons of copies floating around the web, and it's
> a great handbook reference for "just what is the thermal resistance
> with a 4-40 screw through that TO-220 tab onto an aluminum chassis"
>
> It's one of those references which everyone cites.
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LJ
Lux, Jim
Thu, Nov 11, 2021 6:50 PM
On 11/10/21 2:40 PM, Richard (Rick) Karlquist wrote:
I am looking for help choosing a potting compound that
has the following properties:
1. Good for 5,000VAC @ 1 MHz
2. Low RF losses.
3. Low permittivity is preferred
4. Low tempco of permittivity is a want.
5. Something I can implement in my home shop
without access to a vacuum pump etc. is a want.
Thanks in advance
Rick Karlquist N6RK
After consulting the experts at work, what they use for this kind of
thing (HVPS, high power RF, etc.) is:
https://www.elantas.com/pdg/products/tooling-composites-materials/gel-encapsulants-sealants.html
Elantas EN-11 (Conap) Casting, Potting and Molding Compound.
epsilon of 2.9 @ 1 MHz
610 V/mil breakdown
tan d of 0.009 at 1 MHz
8 hour cure at 80C, more than a week at 25C. 50 min pot life
your challenge may be finding it in small quantities - a casual search
shows gallon cans at just under $200, and I'm not sure that you don't
need to buy a part a and a part b.
On 11/10/21 2:40 PM, Richard (Rick) Karlquist wrote:
> I am looking for help choosing a potting compound that
> has the following properties:
>
> 1. Good for 5,000VAC @ 1 MHz
> 2. Low RF losses.
> 3. Low permittivity is preferred
> 4. Low tempco of permittivity is a want.
> 5. Something I can implement in my home shop
> without access to a vacuum pump etc. is a want.
>
> Thanks in advance
>
> Rick Karlquist N6RK
After consulting the experts at work, what they use for this kind of
thing (HVPS, high power RF, etc.) is:
https://www.elantas.com/pdg/products/tooling-composites-materials/gel-encapsulants-sealants.html
Elantas EN-11 (Conap) Casting, Potting and Molding Compound.
epsilon of 2.9 @ 1 MHz
610 V/mil breakdown
tan d of 0.009 at 1 MHz
8 hour cure at 80C, more than a week at 25C. 50 min pot life
your challenge may be finding it in small quantities - a casual search
shows gallon cans at just under $200, and I'm not sure that you don't
need to buy a part a and a part b.
