Empathy List Archives

E

EWKehren@aol.com

Wed, Apr 12, 2017 8:55 PM

Looking back at the dialog I started on Rb’s and the repeated returns to
that subject allow me to make some comments, observations and
recommendations.. I stayed on purpose away from participating but learned a lot. It also
resulted in some off list dialogs with members working on the subject off
list.
Rick’s discussion on why to use two frequencies was for me an eye opener
and gives me clear directions on how to proceed on frequency generation. The
single frequency project is dumped. Corby’s work on filters again
influences our future steps. Using a laser diode and its challenges again an eye
opener and a challenge. We have time nuts that have working systems.
Let’s be honest, we have members with super knowledge but very few have
the appetite to do something with it in the form of hardware. Here is my
proposal that is based on walk before run.
FRK and M100 are next to the HP 5065A the most promising Rb’s in what we
like to do. They are easy to work on specially when you are 75/78 and in my
case have a macular hole.
Optical Filter. Corby actually did insert a filter in a M100 did however
not notice an improvement. When we discussed it come to find out he forgot
to change the time constant so the cell did not control the performance.
This was years ago and like many of us has his hands full with projects. He
decided to pass his M100/FRK to an other time nut and focus on HP and Maser.
We all benefit from these efforts.
Back to filter we have dissected a FRK and a M100 and are convinced that
there is a room for a filter, in case of the FRK, very easy. Corby used a
M100, in my opinion more of a challenge. Will not try it. After discussions
with Corby I now understand that the filter does not filter out a particular
wavelength but most the noise that Rb lamps produce as seen on optical
spectrum analyzers. It improves signal noise ratio after all that is what is
all about. Once we have completed our current projects we may do so.
We are also considering to review the frequency generation using Rick’s
postings as guidance. All this needs measuring capabilities which is what we
are working on. I am fortunate to have access to Corby’s Maser but Juerg
does not have that. We are working on a solution.
There are many FRK/M100’s out there some with low output lamps that would
be a natural for a Laser Diode replacement. The mechanical makeup begs for
a Laser solution. The two units have a cell in size only second to HP5065A
Going to laser would also allow to reduce cell temperature again
contributing to an improved signal noise ratio,
This is way off our expertise but it would be nice if some one would take
the ball and run with it. I am convinced from off list conversations that
$1000 is a reasonable goal.
There is no guarantee that we will do the filter depending what our
results will be on our present work so again maybe some one would carry that
ball.
Both can be a first step for future work. WALK
Bert Kehren

In a message dated 4/11/2017 12:02:09 P.M. Eastern Daylight Time,
attila@kinali.ch writes:

On Tue, 11 Apr 2017 07:31:01 +0000
Andre Andre@Lanoe.net wrote:

Has anyone else either built an atomic clock around a bare Rb lamp

module "core" or attempted

to make a hydrogen maser?

Building my own Rb vapor cell standard or H-maser is on my list
of Things-I-have-to-do-before-I-die :-)

If I had to do one of those now, I would go for a Rb vapor cell
with dual-resonance using an external cavity laser diode for pumping.

The electronics for such a thing are relatively easy, if you are not
afraid of Jiga-Hurts and using these pesky QFN packages. But it isn't
cheap either. There was a discussion started by Bert[1] where I ventured
a rough calculation what I think it wold cost. Though I think I have
understimated the cost of an ECLD (it's more like 1k-5k from what I have
read)

Attila Kinali

[1] search for "thinking outside the box" in the archives

--
It is upon moral qualities that a society is ultimately founded. All
the prosperity and technological sophistication in the world is of no
use without that foundation.
-- Miss Matheson, The Diamond Age, Neil Stephenson

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.

Looking back at the dialog I started on Rb’s and the repeated returns to that subject allow me to make some comments, observations and recommendations.. I stayed on purpose away from participating but learned a lot. It also resulted in some off list dialogs with members working on the subject off list. Rick’s discussion on why to use two frequencies was for me an eye opener and gives me clear directions on how to proceed on frequency generation. The single frequency project is dumped. Corby’s work on filters again influences our future steps. Using a laser diode and its challenges again an eye opener and a challenge. We have time nuts that have working systems. Let’s be honest, we have members with super knowledge but very few have the appetite to do something with it in the form of hardware. Here is my proposal that is based on walk before run. FRK and M100 are next to the HP 5065A the most promising Rb’s in what we like to do. They are easy to work on specially when you are 75/78 and in my case have a macular hole. Optical Filter. Corby actually did insert a filter in a M100 did however not notice an improvement. When we discussed it come to find out he forgot to change the time constant so the cell did not control the performance. This was years ago and like many of us has his hands full with projects. He decided to pass his M100/FRK to an other time nut and focus on HP and Maser. We all benefit from these efforts. Back to filter we have dissected a FRK and a M100 and are convinced that there is a room for a filter, in case of the FRK, very easy. Corby used a M100, in my opinion more of a challenge. Will not try it. After discussions with Corby I now understand that the filter does not filter out a particular wavelength but most the noise that Rb lamps produce as seen on optical spectrum analyzers. It improves signal noise ratio after all that is what is all about. Once we have completed our current projects we may do so. We are also considering to review the frequency generation using Rick’s postings as guidance. All this needs measuring capabilities which is what we are working on. I am fortunate to have access to Corby’s Maser but Juerg does not have that. We are working on a solution. There are many FRK/M100’s out there some with low output lamps that would be a natural for a Laser Diode replacement. The mechanical makeup begs for a Laser solution. The two units have a cell in size only second to HP5065A Going to laser would also allow to reduce cell temperature again contributing to an improved signal noise ratio, This is way off our expertise but it would be nice if some one would take the ball and run with it. I am convinced from off list conversations that $1000 is a reasonable goal. There is no guarantee that we will do the filter depending what our results will be on our present work so again maybe some one would carry that ball. Both can be a first step for future work. WALK Bert Kehren In a message dated 4/11/2017 12:02:09 P.M. Eastern Daylight Time, attila@kinali.ch writes: On Tue, 11 Apr 2017 07:31:01 +0000 Andre <Andre@Lanoe.net> wrote: > Has anyone else either built an atomic clock around a bare Rb lamp module "core" or attempted > > to make a hydrogen maser? Building my own Rb vapor cell standard or H-maser is on my list of Things-I-have-to-do-before-I-die :-) If I had to do one of those now, I would go for a Rb vapor cell with dual-resonance using an external cavity laser diode for pumping. The electronics for such a thing are relatively easy, if you are not afraid of Jiga-Hurts and using these pesky QFN packages. But it isn't cheap either. There was a discussion started by Bert[1] where I ventured a rough calculation what I think it wold cost. Though I think I have understimated the cost of an ECLD (it's more like 1k-5k from what I have read) Attila Kinali [1] search for "thinking outside the box" in the archives -- It is upon moral qualities that a society is ultimately founded. All the prosperity and technological sophistication in the world is of no use without that foundation. -- Miss Matheson, The Diamond Age, Neil Stephenson _______________________________________________ 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.

BK

Bob kb8tq

Wed, Apr 12, 2017 11:19 PM

Hi

There are papers from the mid 90’s talking about improving the GPS Rb’s. Those parts are
as far as I know the best “production” Rb’s out there. The main comment seems to be that
phase noise (in it’s various forms) is a major contributor to the stability of the Rb’s….

Bob

On Apr 12, 2017, at 4:55 PM, Bert Kehren via time-nuts time-nuts@febo.com wrote:

Looking back at the dialog I started on Rb’s and the repeated returns to
that subject allow me to make some comments, observations and
recommendations.. I stayed on purpose away from participating but learned a lot. It also
resulted in some off list dialogs with members working on the subject off
list.
Rick’s discussion on why to use two frequencies was for me an eye opener
and gives me clear directions on how to proceed on frequency generation. The
single frequency project is dumped. Corby’s work on filters again
influences our future steps. Using a laser diode and its challenges again an eye
opener and a challenge. We have time nuts that have working systems.
Let’s be honest, we have members with super knowledge but very few have
the appetite to do something with it in the form of hardware. Here is my
proposal that is based on walk before run.
FRK and M100 are next to the HP 5065A the most promising Rb’s in what we
like to do. They are easy to work on specially when you are 75/78 and in my
case have a macular hole.
Optical Filter. Corby actually did insert a filter in a M100 did however
not notice an improvement. When we discussed it come to find out he forgot
to change the time constant so the cell did not control the performance.
This was years ago and like many of us has his hands full with projects. He
decided to pass his M100/FRK to an other time nut and focus on HP and Maser.
We all benefit from these efforts.
Back to filter we have dissected a FRK and a M100 and are convinced that
there is a room for a filter, in case of the FRK, very easy. Corby used a
M100, in my opinion more of a challenge. Will not try it. After discussions
with Corby I now understand that the filter does not filter out a particular
wavelength but most the noise that Rb lamps produce as seen on optical
spectrum analyzers. It improves signal noise ratio after all that is what is
all about. Once we have completed our current projects we may do so.
We are also considering to review the frequency generation using Rick’s
postings as guidance. All this needs measuring capabilities which is what we
are working on. I am fortunate to have access to Corby’s Maser but Juerg
does not have that. We are working on a solution.
There are many FRK/M100’s out there some with low output lamps that would
be a natural for a Laser Diode replacement. The mechanical makeup begs for
a Laser solution. The two units have a cell in size only second to HP5065A
Going to laser would also allow to reduce cell temperature again
contributing to an improved signal noise ratio,
This is way off our expertise but it would be nice if some one would take
the ball and run with it. I am convinced from off list conversations that
$1000 is a reasonable goal.
There is no guarantee that we will do the filter depending what our
results will be on our present work so again maybe some one would carry that
ball.
Both can be a first step for future work. WALK
Bert Kehren

In a message dated 4/11/2017 12:02:09 P.M. Eastern Daylight Time,
attila@kinali.ch writes:

On Tue, 11 Apr 2017 07:31:01 +0000
Andre Andre@Lanoe.net wrote:

Has anyone else either built an atomic clock around a bare Rb lamp

module "core" or attempted

to make a hydrogen maser?

Building my own Rb vapor cell standard or H-maser is on my list
of Things-I-have-to-do-before-I-die :-)

If I had to do one of those now, I would go for a Rb vapor cell
with dual-resonance using an external cavity laser diode for pumping.

The electronics for such a thing are relatively easy, if you are not
afraid of Jiga-Hurts and using these pesky QFN packages. But it isn't
cheap either. There was a discussion started by Bert[1] where I ventured
a rough calculation what I think it wold cost. Though I think I have
understimated the cost of an ECLD (it's more like 1k-5k from what I have
read)

Attila Kinali

[1] search for "thinking outside the box" in the archives

--
It is upon moral qualities that a society is ultimately founded. All
the prosperity and technological sophistication in the world is of no
use without that foundation.
-- Miss Matheson, The Diamond Age, Neil Stephenson

time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to
https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.

time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.

Hi There are papers from the mid 90’s talking about improving the GPS Rb’s. Those parts are as far as I know the best “production” Rb’s out there. The main comment seems to be that phase noise (in it’s various forms) is a major contributor to the stability of the Rb’s…. Bob > On Apr 12, 2017, at 4:55 PM, Bert Kehren via time-nuts <time-nuts@febo.com> wrote: > > Looking back at the dialog I started on Rb’s and the repeated returns to > that subject allow me to make some comments, observations and > recommendations.. I stayed on purpose away from participating but learned a lot. It also > resulted in some off list dialogs with members working on the subject off > list. > Rick’s discussion on why to use two frequencies was for me an eye opener > and gives me clear directions on how to proceed on frequency generation. The > single frequency project is dumped. Corby’s work on filters again > influences our future steps. Using a laser diode and its challenges again an eye > opener and a challenge. We have time nuts that have working systems. > Let’s be honest, we have members with super knowledge but very few have > the appetite to do something with it in the form of hardware. Here is my > proposal that is based on walk before run. > FRK and M100 are next to the HP 5065A the most promising Rb’s in what we > like to do. They are easy to work on specially when you are 75/78 and in my > case have a macular hole. > Optical Filter. Corby actually did insert a filter in a M100 did however > not notice an improvement. When we discussed it come to find out he forgot > to change the time constant so the cell did not control the performance. > This was years ago and like many of us has his hands full with projects. He > decided to pass his M100/FRK to an other time nut and focus on HP and Maser. > We all benefit from these efforts. > Back to filter we have dissected a FRK and a M100 and are convinced that > there is a room for a filter, in case of the FRK, very easy. Corby used a > M100, in my opinion more of a challenge. Will not try it. After discussions > with Corby I now understand that the filter does not filter out a particular > wavelength but most the noise that Rb lamps produce as seen on optical > spectrum analyzers. It improves signal noise ratio after all that is what is > all about. Once we have completed our current projects we may do so. > We are also considering to review the frequency generation using Rick’s > postings as guidance. All this needs measuring capabilities which is what we > are working on. I am fortunate to have access to Corby’s Maser but Juerg > does not have that. We are working on a solution. > There are many FRK/M100’s out there some with low output lamps that would > be a natural for a Laser Diode replacement. The mechanical makeup begs for > a Laser solution. The two units have a cell in size only second to HP5065A > Going to laser would also allow to reduce cell temperature again > contributing to an improved signal noise ratio, > This is way off our expertise but it would be nice if some one would take > the ball and run with it. I am convinced from off list conversations that > $1000 is a reasonable goal. > There is no guarantee that we will do the filter depending what our > results will be on our present work so again maybe some one would carry that > ball. > Both can be a first step for future work. WALK > Bert Kehren > > > In a message dated 4/11/2017 12:02:09 P.M. Eastern Daylight Time, > attila@kinali.ch writes: > > On Tue, 11 Apr 2017 07:31:01 +0000 > Andre <Andre@Lanoe.net> wrote: > >> Has anyone else either built an atomic clock around a bare Rb lamp > module "core" or attempted >> >> to make a hydrogen maser? > > Building my own Rb vapor cell standard or H-maser is on my list > of Things-I-have-to-do-before-I-die :-) > > If I had to do one of those now, I would go for a Rb vapor cell > with dual-resonance using an external cavity laser diode for pumping. > > The electronics for such a thing are relatively easy, if you are not > afraid of Jiga-Hurts and using these pesky QFN packages. But it isn't > cheap either. There was a discussion started by Bert[1] where I ventured > a rough calculation what I think it wold cost. Though I think I have > understimated the cost of an ECLD (it's more like 1k-5k from what I have > read) > > > Attila Kinali > > [1] search for "thinking outside the box" in the archives > > -- > It is upon moral qualities that a society is ultimately founded. All > the prosperity and technological sophistication in the world is of no > use without that foundation. > -- Miss Matheson, The Diamond Age, Neil Stephenson > _______________________________________________ > time-nuts mailing list -- time-nuts@febo.com > To unsubscribe, go to > https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. > > _______________________________________________ > time-nuts mailing list -- time-nuts@febo.com > To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there.

BG

Bruce Griffiths

Thu, Apr 13, 2017 12:23 AM

Typically External Cavity diode lasers use either the Littrow or the Littman-Metcalf configurations.

A typical Littrow configuration is:

http://www.moglabs.com/uploads/2/4/2/1/24212474/manual_ecd_rev4.20.pdf

Alternatively a cat eye external cavity can be used:

http://www.moglabs.com/uploads/2/4/2/1/24212474/moglabs_cel002_manual_rev108.pdf

To assist with tuning the laser a wavemeter is helpful:

http://www.iaea.org/inis/collection/NCLCollectionStore/_Public/31/004/31004208.pdf

Other variants based on optical wedges or even a simple grating can also be used together with a CCD camera or equivalent to achieve an accuracy approaching a few pm.

Whilst AR coated laser diodes work best its also possible to use uncoated laser diodes.

Such diodes have been successfully used for atomic spectroscopy of rubidium vapour by several groups.

Temperature control of the laser diode and cavity are the most critical issues.

One can easily adapt standard optical mounts to make one's own ECDL but temperature control is critical for use in a rubidium standard.

Locking the laser to the absorption line of interest relaxes the required long term stability of the ECDL itself.

Bruce

 On 13 April 2017 at 08:55 Bert Kehren via time-nuts <time-nuts@febo.com> wrote:

 Looking back at the dialog I started on Rb’s and the repeated returns to
 that subject allow me to make some comments, observations and
 recommendations.. I stayed on purpose away from participating but learned a lot. It also
 resulted in some off list dialogs with members working on the subject off
 list.
 Rick’s discussion on why to use two frequencies was for me an eye opener
 and gives me clear directions on how to proceed on frequency generation. The
 single frequency project is dumped. Corby’s work on filters again
 influences our future steps. Using a laser diode and its challenges again an eye
 opener and a challenge. We have time nuts that have working systems.
 Let’s be honest, we have members with super knowledge but very few have
 the appetite to do something with it in the form of hardware. Here is my
 proposal that is based on walk before run.
 FRK and M100 are next to the HP 5065A the most promising Rb’s in what we
 like to do. They are easy to work on specially when you are 75/78 and in my
 case have a macular hole.
 Optical Filter. Corby actually did insert a filter in a M100 did however
 not notice an improvement. When we discussed it come to find out he forgot
 to change the time constant so the cell did not control the performance.
 This was years ago and like many of us has his hands full with projects. He
 decided to pass his M100/FRK to an other time nut and focus on HP and Maser.
 We all benefit from these efforts.
 Back to filter we have dissected a FRK and a M100 and are convinced that
 there is a room for a filter, in case of the FRK, very easy. Corby used a
 M100, in my opinion more of a challenge. Will not try it. After discussions
 with Corby I now understand that the filter does not filter out a particular
 wavelength but most the noise that Rb lamps produce as seen on optical
 spectrum analyzers. It improves signal noise ratio after all that is what is
 all about. Once we have completed our current projects we may do so.
 We are also considering to review the frequency generation using Rick’s
 postings as guidance. All this needs measuring capabilities which is what we
 are working on. I am fortunate to have access to Corby’s Maser but Juerg
 does not have that. We are working on a solution.
 There are many FRK/M100’s out there some with low output lamps that would
 be a natural for a Laser Diode replacement. The mechanical makeup begs for
 a Laser solution. The two units have a cell in size only second to HP5065A
 Going to laser would also allow to reduce cell temperature again
 contributing to an improved signal noise ratio,
 This is way off our expertise but it would be nice if some one would take
 the ball and run with it. I am convinced from off list conversations that
 $1000 is a reasonable goal.
 There is no guarantee that we will do the filter depending what our
 results will be on our present work so again maybe some one would carry that
 ball.
 Both can be a first step for future work. WALK
 Bert Kehren

 In a message dated 4/11/2017 12:02:09 P.M. Eastern Daylight Time,
 attila@kinali.ch writes:

 On Tue, 11 Apr 2017 07:31:01 +0000
 Andre <Andre@Lanoe.net> wrote:

     Has anyone else either built an atomic clock around a bare Rb lamp
     module "core" or attempted

     to make a hydrogen maser?

 Building my own Rb vapor cell standard or H-maser is on my list
 of Things-I-have-to-do-before-I-die :-)

 If I had to do one of those now, I would go for a Rb vapor cell
 with dual-resonance using an external cavity laser diode for pumping.

 The electronics for such a thing are relatively easy, if you are not
 afraid of Jiga-Hurts and using these pesky QFN packages. But it isn't
 cheap either. There was a discussion started by Bert[1] where I ventured
 a rough calculation what I think it wold cost. Though I think I have
 understimated the cost of an ECLD (it's more like 1k-5k from what I have
 read)

 Attila Kinali

 [1] search for "thinking outside the box" in the archives

 --
 It is upon moral qualities that a society is ultimately founded. All
 the prosperity and technological sophistication in the world is of no
 use without that foundation.
 -- Miss Matheson, The Diamond Age, Neil Stephenson

 _______________________________________________
 time-nuts mailing list -- time-nuts@febo.com
 To unsubscribe, go to
 https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
 and follow the instructions there.

 _______________________________________________
 time-nuts mailing list -- time-nuts@febo.com
 To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
 and follow the instructions there.

Typically External Cavity diode lasers use either the Littrow or the Littman-Metcalf configurations. A typical Littrow configuration is: http://www.moglabs.com/uploads/2/4/2/1/24212474/manual_ecd_rev4.20.pdf Alternatively a cat eye external cavity can be used: http://www.moglabs.com/uploads/2/4/2/1/24212474/moglabs_cel002_manual_rev108.pdf To assist with tuning the laser a wavemeter is helpful: http://www.iaea.org/inis/collection/NCLCollectionStore/_Public/31/004/31004208.pdf Other variants based on optical wedges or even a simple grating can also be used together with a CCD camera or equivalent to achieve an accuracy approaching a few pm. Whilst AR coated laser diodes work best its also possible to use uncoated laser diodes. Such diodes have been successfully used for atomic spectroscopy of rubidium vapour by several groups. Temperature control of the laser diode and cavity are the most critical issues. One can easily adapt standard optical mounts to make one's own ECDL but temperature control is critical for use in a rubidium standard. Locking the laser to the absorption line of interest relaxes the required long term stability of the ECDL itself. Bruce > > On 13 April 2017 at 08:55 Bert Kehren via time-nuts <time-nuts@febo.com> wrote: > > Looking back at the dialog I started on Rb’s and the repeated returns to > that subject allow me to make some comments, observations and > recommendations.. I stayed on purpose away from participating but learned a lot. It also > resulted in some off list dialogs with members working on the subject off > list. > Rick’s discussion on why to use two frequencies was for me an eye opener > and gives me clear directions on how to proceed on frequency generation. The > single frequency project is dumped. Corby’s work on filters again > influences our future steps. Using a laser diode and its challenges again an eye > opener and a challenge. We have time nuts that have working systems. > Let’s be honest, we have members with super knowledge but very few have > the appetite to do something with it in the form of hardware. Here is my > proposal that is based on walk before run. > FRK and M100 are next to the HP 5065A the most promising Rb’s in what we > like to do. They are easy to work on specially when you are 75/78 and in my > case have a macular hole. > Optical Filter. Corby actually did insert a filter in a M100 did however > not notice an improvement. When we discussed it come to find out he forgot > to change the time constant so the cell did not control the performance. > This was years ago and like many of us has his hands full with projects. He > decided to pass his M100/FRK to an other time nut and focus on HP and Maser. > We all benefit from these efforts. > Back to filter we have dissected a FRK and a M100 and are convinced that > there is a room for a filter, in case of the FRK, very easy. Corby used a > M100, in my opinion more of a challenge. Will not try it. After discussions > with Corby I now understand that the filter does not filter out a particular > wavelength but most the noise that Rb lamps produce as seen on optical > spectrum analyzers. It improves signal noise ratio after all that is what is > all about. Once we have completed our current projects we may do so. > We are also considering to review the frequency generation using Rick’s > postings as guidance. All this needs measuring capabilities which is what we > are working on. I am fortunate to have access to Corby’s Maser but Juerg > does not have that. We are working on a solution. > There are many FRK/M100’s out there some with low output lamps that would > be a natural for a Laser Diode replacement. The mechanical makeup begs for > a Laser solution. The two units have a cell in size only second to HP5065A > Going to laser would also allow to reduce cell temperature again > contributing to an improved signal noise ratio, > This is way off our expertise but it would be nice if some one would take > the ball and run with it. I am convinced from off list conversations that > $1000 is a reasonable goal. > There is no guarantee that we will do the filter depending what our > results will be on our present work so again maybe some one would carry that > ball. > Both can be a first step for future work. WALK > Bert Kehren > > In a message dated 4/11/2017 12:02:09 P.M. Eastern Daylight Time, > attila@kinali.ch writes: > > On Tue, 11 Apr 2017 07:31:01 +0000 > Andre <Andre@Lanoe.net> wrote: > > > > > > Has anyone else either built an atomic clock around a bare Rb lamp > > module "core" or attempted > > > > to make a hydrogen maser? > > > > > > Building my own Rb vapor cell standard or H-maser is on my list > of Things-I-have-to-do-before-I-die :-) > > If I had to do one of those now, I would go for a Rb vapor cell > with dual-resonance using an external cavity laser diode for pumping. > > The electronics for such a thing are relatively easy, if you are not > afraid of Jiga-Hurts and using these pesky QFN packages. But it isn't > cheap either. There was a discussion started by Bert[1] where I ventured > a rough calculation what I think it wold cost. Though I think I have > understimated the cost of an ECLD (it's more like 1k-5k from what I have > read) > > Attila Kinali > > [1] search for "thinking outside the box" in the archives > > -- > It is upon moral qualities that a society is ultimately founded. All > the prosperity and technological sophistication in the world is of no > use without that foundation. > -- Miss Matheson, The Diamond Age, Neil Stephenson > > _______________________________________________ > time-nuts mailing list -- time-nuts@febo.com > To unsubscribe, go to > https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. > > _______________________________________________ > time-nuts mailing list -- time-nuts@febo.com > To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. >

MD

Magnus Danielson

Mon, Apr 17, 2017 11:49 AM

Hi,

On that note we have Rick Karlquists article showing how he replaced the
traditional syntheis chain with an oscillator at the target frequency,
locked to the lower frequency. Benefit is in the phase-noise.
This was from the fine work on the 5071A.

This approach can be used for rubidiums too, if you care about phase
noise going into the cavity.

The traditional chain has essentially only one oscillator, but one leg
in the synthesis chain has a phase-modulation with the modulation
frequency for the sensing of the atomic reference.

Cheers,
Magnus

On 04/13/2017 01:19 AM, Bob kb8tq wrote:

Hi

There are papers from the mid 90’s talking about improving the GPS Rb’s. Those parts are
as far as I know the best “production” Rb’s out there. The main comment seems to be that
phase noise (in it’s various forms) is a major contributor to the stability of the Rb’s….

Bob

On Apr 12, 2017, at 4:55 PM, Bert Kehren via time-nuts time-nuts@febo.com wrote:

Looking back at the dialog I started on Rb’s and the repeated returns to
that subject allow me to make some comments, observations and
recommendations.. I stayed on purpose away from participating but learned a lot. It also
resulted in some off list dialogs with members working on the subject off
list.
Rick’s discussion on why to use two frequencies was for me an eye opener
and gives me clear directions on how to proceed on frequency generation. The
single frequency project is dumped. Corby’s work on filters again
influences our future steps. Using a laser diode and its challenges again an eye
opener and a challenge. We have time nuts that have working systems.
Let’s be honest, we have members with super knowledge but very few have
the appetite to do something with it in the form of hardware. Here is my
proposal that is based on walk before run.
FRK and M100 are next to the HP 5065A the most promising Rb’s in what we
like to do. They are easy to work on specially when you are 75/78 and in my
case have a macular hole.
Optical Filter. Corby actually did insert a filter in a M100 did however
not notice an improvement. When we discussed it come to find out he forgot
to change the time constant so the cell did not control the performance.
This was years ago and like many of us has his hands full with projects. He
decided to pass his M100/FRK to an other time nut and focus on HP and Maser.
We all benefit from these efforts.
Back to filter we have dissected a FRK and a M100 and are convinced that
there is a room for a filter, in case of the FRK, very easy. Corby used a
M100, in my opinion more of a challenge. Will not try it. After discussions
with Corby I now understand that the filter does not filter out a particular
wavelength but most the noise that Rb lamps produce as seen on optical
spectrum analyzers. It improves signal noise ratio after all that is what is
all about. Once we have completed our current projects we may do so.
We are also considering to review the frequency generation using Rick’s
postings as guidance. All this needs measuring capabilities which is what we
are working on. I am fortunate to have access to Corby’s Maser but Juerg
does not have that. We are working on a solution.
There are many FRK/M100’s out there some with low output lamps that would
be a natural for a Laser Diode replacement. The mechanical makeup begs for
a Laser solution. The two units have a cell in size only second to HP5065A
Going to laser would also allow to reduce cell temperature again
contributing to an improved signal noise ratio,
This is way off our expertise but it would be nice if some one would take
the ball and run with it. I am convinced from off list conversations that
$1000 is a reasonable goal.
There is no guarantee that we will do the filter depending what our
results will be on our present work so again maybe some one would carry that
ball.
Both can be a first step for future work. WALK
Bert Kehren

In a message dated 4/11/2017 12:02:09 P.M. Eastern Daylight Time,
attila@kinali.ch writes:

On Tue, 11 Apr 2017 07:31:01 +0000
Andre Andre@Lanoe.net wrote:

Has anyone else either built an atomic clock around a bare Rb lamp

module "core" or attempted

to make a hydrogen maser?

Building my own Rb vapor cell standard or H-maser is on my list
of Things-I-have-to-do-before-I-die :-)

If I had to do one of those now, I would go for a Rb vapor cell
with dual-resonance using an external cavity laser diode for pumping.

The electronics for such a thing are relatively easy, if you are not
afraid of Jiga-Hurts and using these pesky QFN packages. But it isn't
cheap either. There was a discussion started by Bert[1] where I ventured
a rough calculation what I think it wold cost. Though I think I have
understimated the cost of an ECLD (it's more like 1k-5k from what I have
read)

Attila Kinali

[1] search for "thinking outside the box" in the archives

--
It is upon moral qualities that a society is ultimately founded. All
the prosperity and technological sophistication in the world is of no
use without that foundation.
-- Miss Matheson, The Diamond Age, Neil Stephenson

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Hi, On that note we have Rick Karlquists article showing how he replaced the traditional syntheis chain with an oscillator at the target frequency, locked to the lower frequency. Benefit is in the phase-noise. This was from the fine work on the 5071A. This approach can be used for rubidiums too, if you care about phase noise going into the cavity. The traditional chain has essentially only one oscillator, but one leg in the synthesis chain has a phase-modulation with the modulation frequency for the sensing of the atomic reference. Cheers, Magnus On 04/13/2017 01:19 AM, Bob kb8tq wrote: > Hi > > There are papers from the mid 90’s talking about improving the GPS Rb’s. Those parts are > as far as I know the best “production” Rb’s out there. The main comment seems to be that > phase noise (in it’s various forms) is a major contributor to the stability of the Rb’s…. > > Bob > >> On Apr 12, 2017, at 4:55 PM, Bert Kehren via time-nuts <time-nuts@febo.com> wrote: >> >> Looking back at the dialog I started on Rb’s and the repeated returns to >> that subject allow me to make some comments, observations and >> recommendations.. I stayed on purpose away from participating but learned a lot. It also >> resulted in some off list dialogs with members working on the subject off >> list. >> Rick’s discussion on why to use two frequencies was for me an eye opener >> and gives me clear directions on how to proceed on frequency generation. The >> single frequency project is dumped. Corby’s work on filters again >> influences our future steps. Using a laser diode and its challenges again an eye >> opener and a challenge. We have time nuts that have working systems. >> Let’s be honest, we have members with super knowledge but very few have >> the appetite to do something with it in the form of hardware. Here is my >> proposal that is based on walk before run. >> FRK and M100 are next to the HP 5065A the most promising Rb’s in what we >> like to do. They are easy to work on specially when you are 75/78 and in my >> case have a macular hole. >> Optical Filter. Corby actually did insert a filter in a M100 did however >> not notice an improvement. When we discussed it come to find out he forgot >> to change the time constant so the cell did not control the performance. >> This was years ago and like many of us has his hands full with projects. He >> decided to pass his M100/FRK to an other time nut and focus on HP and Maser. >> We all benefit from these efforts. >> Back to filter we have dissected a FRK and a M100 and are convinced that >> there is a room for a filter, in case of the FRK, very easy. Corby used a >> M100, in my opinion more of a challenge. Will not try it. After discussions >> with Corby I now understand that the filter does not filter out a particular >> wavelength but most the noise that Rb lamps produce as seen on optical >> spectrum analyzers. It improves signal noise ratio after all that is what is >> all about. Once we have completed our current projects we may do so. >> We are also considering to review the frequency generation using Rick’s >> postings as guidance. All this needs measuring capabilities which is what we >> are working on. I am fortunate to have access to Corby’s Maser but Juerg >> does not have that. We are working on a solution. >> There are many FRK/M100’s out there some with low output lamps that would >> be a natural for a Laser Diode replacement. The mechanical makeup begs for >> a Laser solution. The two units have a cell in size only second to HP5065A >> Going to laser would also allow to reduce cell temperature again >> contributing to an improved signal noise ratio, >> This is way off our expertise but it would be nice if some one would take >> the ball and run with it. I am convinced from off list conversations that >> $1000 is a reasonable goal. >> There is no guarantee that we will do the filter depending what our >> results will be on our present work so again maybe some one would carry that >> ball. >> Both can be a first step for future work. WALK >> Bert Kehren >> >> >> In a message dated 4/11/2017 12:02:09 P.M. Eastern Daylight Time, >> attila@kinali.ch writes: >> >> On Tue, 11 Apr 2017 07:31:01 +0000 >> Andre <Andre@Lanoe.net> wrote: >> >>> Has anyone else either built an atomic clock around a bare Rb lamp >> module "core" or attempted >>> >>> to make a hydrogen maser? >> >> Building my own Rb vapor cell standard or H-maser is on my list >> of Things-I-have-to-do-before-I-die :-) >> >> If I had to do one of those now, I would go for a Rb vapor cell >> with dual-resonance using an external cavity laser diode for pumping. >> >> The electronics for such a thing are relatively easy, if you are not >> afraid of Jiga-Hurts and using these pesky QFN packages. But it isn't >> cheap either. There was a discussion started by Bert[1] where I ventured >> a rough calculation what I think it wold cost. Though I think I have >> understimated the cost of an ECLD (it's more like 1k-5k from what I have >> read) >> >> >> Attila Kinali >> >> [1] search for "thinking outside the box" in the archives >> >> -- >> It is upon moral qualities that a society is ultimately founded. All >> the prosperity and technological sophistication in the world is of no >> use without that foundation. >> -- Miss Matheson, The Diamond Age, Neil Stephenson >> _______________________________________________ >> time-nuts mailing list -- time-nuts@febo.com >> To unsubscribe, go to >> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts >> and follow the instructions there. >> >> _______________________________________________ >> time-nuts mailing list -- time-nuts@febo.com >> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts >> and follow the instructions there. > > _______________________________________________ > 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] Re. DIY atomic "resonator"