Re: [time-nuts] hm H Maser

[Bruce Griffiths]

An entire room kept near to absolute zero with a simple door access???Unlikely, 
likely the writer is unfamiliar with science/engineering.
Bruce 

On Saturday, 14 January 2017 11:39 AM, Gary Woods 
 wrote:
 

 Hydrogen maser in radio astronomy to sync worldwide systems:

http://flip.it/rmbdRQ

(Lifted from the Albany, NY astronomy group).



-- 
Gary Woods O- K2AHC  Public keys at home.earthlink.net/~garygarlic, or get 
0x1D64A93D via keyserver
fingerprint =  E2 6F 50 93 7B C7 F3 CA  1F 8B 3C C0 B0 28 68 0B
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Re: [time-nuts] hm H Maser

[Gary Woods]

Hydrogen maser in radio astronomy to sync worldwide systems:

http://flip.it/rmbdRQ

(Lifted from the Albany, NY astronomy group).



-- 
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Re: [time-nuts] hm H Maser

[Bob Camp]

Hi

The obvious question would be: What does it cost to set up a line to make a 
proper
set of spherical Rb cells? Doing this as a glassblowing project is a dead end. 
You
need it properly tooled ….

Bob

> On Jan 11, 2017, at 7:05 PM, Bruce Griffiths  
> wrote:
> 
> Angus
> Read the paper I posted on the current state of the art.
> ADEV ~ 2E-13/SQRT(Tau) is feasible with large cells and using a laser instead 
> of rubidium lamp.In principle, one can use the same cell to lock the laser to 
> the rubidium absorption line and lock the microwave signal.Suitable laser 
> diodes are readily available.
> Increasing the contrast of the signal used for locking reduces the noise 
> significantly.One approach is to use an integrating sphere cell and use an 
> optical fibre to bring the laser signal into the cell.Since random scattering 
> in an integrating sphere depolarises the light and virtually eliminates any 
> effect of spatial coherence a multimode fibre should suffice.Laser speckle 
> can be reduced significantly by using a colloidal suspension of titanium 
> dioxide if the colloidal suspension fills another integrating sphere or 
> equivalent.I've tried the latter using plastic optical fibres to transport 
> the laser light into and out of the colloid. Its extremely effective in 
> eliminating speckle in an optical interferometer.
> Bruce 
> 
>On Thursday, 12 January 2017 12:19 PM, Angus  
> wrote:
> 
> 
> On Tue, 10 Jan 2017 21:43:07 -0500, you wrote:
> 
>> 
>> This does get back to state of the art Rb and what that means. In my 
>> suggested case thats measured in terms of ADEV for Tau = 1 to 1,000,000 
>> seconds. If you wanted an Rb with (only) state of the art phase noise at 1 
>> MHz offset … thats a different thing. State of the art for 
>> power consumption and size is also not what Im suggesting in this case. Why 
>> the choice of spec? … this is TimeNuts. 
> 
> Hi,
> 
> Some discussions on the performance that might be practically achieved
> with different designs may be a useful start - as long as it's done in
> the context of a practical unit that could actually get built, rather
> than just a theoretical wish list.
> 
> It would also be good to have some idea of the cost of any special
> parts like cells too. Without that info, it's hard to know how
> practical particular designs would be. 
> 
> Looking at export/technology controls might be useful early on too,
> since we're going for high performance.
> 
> I've often wondered how a 21st century version of a 5065 would
> perform, so it's great to see that I'm not completely alone in my
> insanity!
> 
> Angus.
> 
> 
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> 
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Re: [time-nuts] hm H Maser

[Bruce Griffiths]

Angus
Read the paper I posted on the current state of the art.
ADEV ~ 2E-13/SQRT(Tau) is feasible with large cells and using a laser instead 
of rubidium lamp.In principle, one can use the same cell to lock the laser to 
the rubidium absorption line and lock the microwave signal.Suitable laser 
diodes are readily available.
Increasing the contrast of the signal used for locking reduces the noise 
significantly.One approach is to use an integrating sphere cell and use an 
optical fibre to bring the laser signal into the cell.Since random scattering 
in an integrating sphere depolarises the light and virtually eliminates any 
effect of spatial coherence a multimode fibre should suffice.Laser speckle can 
be reduced significantly by using a colloidal suspension of titanium dioxide if 
the colloidal suspension fills another integrating sphere or equivalent.I've 
tried the latter using plastic optical fibres to transport the laser light into 
and out of the colloid. Its extremely effective in eliminating speckle in an 
optical interferometer.
Bruce 

On Thursday, 12 January 2017 12:19 PM, Angus  
wrote:
 

 On Tue, 10 Jan 2017 21:43:07 -0500, you wrote:

>
>This does get back to state of the art Rb and what that means. In my suggested 
>case thats measured in terms of ADEV for Tau = 1 to 1,000,000 
>seconds. If you wanted an Rb with (only) state of the art phase noise at 1 MHz 
>offset … thats a different thing. State of the art for 
>power consumption and size is also not what Im suggesting in this case. Why 
>the choice of spec? … this is TimeNuts. 

Hi,

Some discussions on the performance that might be practically achieved
with different designs may be a useful start - as long as it's done in
the context of a practical unit that could actually get built, rather
than just a theoretical wish list.

It would also be good to have some idea of the cost of any special
parts like cells too. Without that info, it's hard to know how
practical particular designs would be. 

Looking at export/technology controls might be useful early on too,
since we're going for high performance.

I've often wondered how a 21st century version of a 5065 would
perform, so it's great to see that I'm not completely alone in my
insanity!

Angus.


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Re: [time-nuts] hm H Maser

[Bob Camp]

Hi

> On Jan 11, 2017, at 6:07 PM, Angus  wrote:
> 
> On Tue, 10 Jan 2017 21:43:07 -0500, you wrote:
> 
>> 
>> This does get back to “state of the art Rb” and what that means. In my 
>> suggested case that’s measured in terms of ADEV for Tau = 1 to 1,000,000 
>> seconds. If you wanted an Rb with (only) state of the art phase noise at 1 
>> MHz offset 
> that’s a different thing. State of the art for 
>> power consumption and size is also not what I’m suggesting in this case. Why 
>> the choice of spec? 
> this is TimeNuts. 
> 
> Hi,
> 
> Some discussions on the performance that might be practically achieved
> with different designs may be a useful start - as long as it's done in
> the context of a practical unit that could actually get built, rather
> than just a theoretical wish list.
> 

The biggest issue with doing this is that *if* there is a magic formula that 
tells you 
“these parts give you that ADEV” …. it’s in the same vault as the formula for 
Coke. 
That sort of thing (if it even exists) would be the gold standard of corporate 
IP for
a company making atomic clocks. 

About all you can really say is “they did this and the units the shipped did 
that”. There
are some obvious thing like “bigger cells work better”. Coming up with an 
equation that
correctly predicts a cell of this odd geometry functioning at these dimensions 
for 10,000
second ADEV ….not so much. 

> It would also be good to have some idea of the cost of any special
> parts like cells too. Without that info, it's hard to know how
> practical particular designs would be. 

The most likely course would be to cut out a major chunk of cost and find 
somebody
who is willing to make up a couple hundred sets of cells. There has already been
a proposal to do this floated on the list. I don’t recall the exact numbers, 
but $2,000
is what comes to mind. Apologies if this is a bogus number. 

> 
> Looking at export/technology controls might be useful early on too,
> since we're going for high performance.

Indeed, if you get to crazy you could get in trouble. My guess is that a 
standard the 
size of a 5065 or larger is unlikely to set off alarm bells. 


> 
> I've often wondered how a 21st century version of a 5065 would
> perform, so it's great to see that I'm not completely alone in my
> insanity!

Which obviously is an itch many of us share. The gotcha of course is that each 
of 
us has (likely incompatible) ideas about how to do it. We may even have 
incompatible goals in terms of “what’s good”. Based on many decades of 
designing 
things like this, feature creep and elastic goals will kill a project dead 
(usually after
a lot of money has been spent). 

Lots of Fun

Bob

> 
> Angus.
> 
> 
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Re: [time-nuts] hm H Maser

[Angus]

On Tue, 10 Jan 2017 21:43:07 -0500, you wrote:

>
>This does get back to “state of the art Rb” and what that means. In my 
>suggested case that’s measured in terms of ADEV for Tau = 1 to 1,000,000 
>seconds. If you wanted an Rb with (only) state of the art phase noise at 1 MHz 
>offset … that’s a different thing. State of the art for 
>power consumption and size is also not what I’m suggesting in this case. Why 
>the choice of spec? … this is TimeNuts. 

Hi,

Some discussions on the performance that might be practically achieved
with different designs may be a useful start - as long as it's done in
the context of a practical unit that could actually get built, rather
than just a theoretical wish list.

It would also be good to have some idea of the cost of any special
parts like cells too. Without that info, it's hard to know how
practical particular designs would be. 

Looking at export/technology controls might be useful early on too,
since we're going for high performance.

I've often wondered how a 21st century version of a 5065 would
perform, so it's great to see that I'm not completely alone in my
insanity!

Angus.


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Re: [time-nuts] hm H Maser

[Bob Camp]

Hi

A spherical set of cells is going to be a massive pain to fabricate. I believe 
you can hit < 5x10^-12 / sqrt(tau) with 
a fairly normal cell design and cavity design. There are some very basic issues 
with the photo detector’s S/N that
also tip things towards a coaxial approach.

Bob

> On Jan 10, 2017, at 10:43 PM, Bruce Griffiths  
> wrote:
> 
> A  spherical cavity resonator with a spherical Rubidium cell configured as an 
> integrating sphere (to enhance the SNR of the optical absorption signal) is a 
> potential option. Its also possible to use the same cell to lock a 795 nm 
> laser to the desired wavelength. Fiber coupling the laser light could also be 
> useful.Note that with an integrating sphere (or any other random scattering 
> process eg scattering from colloidal particles undergoing Brownian motion) 
> laser polarisation isn't preserved which may be convenient.One potential 
> issue with an  integrating sphere is the longevity of the diffusing coating 
> (typically Barium sulphate with an organic binder). Roughening (fine grind  
> followed by HF etch for stress relief) the outer surface of the cell is also 
> advisable to eliminate light pipe effects in the cell wall.
> Bruce 
> 
>On Wednesday, 11 January 2017 3:54 PM, Bruce Griffiths 
>  wrote:
> 
> 
> A goal with ADEV ~ 1E-13/Tau (for Tau <1000sec) may be feasible as its 
> already been done as part of a PhD thesis.Using as large a cavity as possible 
> is probably useful so that a large cell can be employed.What resonant mode is 
> desirable in the cavity?Do we need to avoid field reversal as in the hydrogen 
> maser?
> Bruce  
> 
>On Wednesday, 11 January 2017 3:43 PM, Bob Camp  wrote:
> 
> 

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Re: [time-nuts] hm H Maser

[Bob Camp]

Hi

A cryo pump will get you into reliability issues if run 24/7. It also is 
doubtful 
that you will be able to maintain the vacuum level over long periods.

Bob

> On Jan 11, 2017, at 12:09 AM, Bruce Griffiths  
> wrote:
> 
> One could always use a cryo pump.
> The following paper is a summary of the current state of the art for rubidium 
> vapour frequency 
> standards:http://www.euramet.org/Media/docs/Repository/A169/IND55/micalizio_02182015.pdf
> 
> Bruce 
> 
>On Wednesday, 11 January 2017 5:15 PM, Ole Petter Ronningen 
>  wrote:
> 
> 
> Add to this ion-pumps (in the case of EFOS type masers 2 every ~2 years),
> plus substantial tooling (turbomolecular vacuum pump, anyone?) to service
> the thing - unless you want the manufacturer to do so..
> 
> Ole
> 
> On Tue, Jan 10, 2017 at 11:12 PM, Dr. David Kirkby (Kirkby Microwave Ltd) <
> drkir...@kirkbymicrowave.co.uk> wrote:
> 
>> On 10 January 2017 at 15:35, Ole Petter Rønningen 
>> wrote:
>> 
>>> ... having said that, I for one think I'm with Bob on this one. The thing
>>> about masers are that they are big. At least active masers. And they
>>> require a substantial volume be kept at ultra high vacuum - which is not
>>> trivial, especially not in a homeshop. The cavity needs to be kept at a
>>> temperature stable to 0.001 degree C. With 4-5 magnetic shields. Add to
>>> this costly pumps to keep the vacuum this low even if you succeed at
>>> reaching that vacuum.. There's easily 1-2KUSD running cost per year just
>> to
>>> keep the maser running.
>>> 
>> 
>> Looking at the Microsemi MHM 2010 Active Hydogen Maser data sheet, the
>> maser has a peak power of 150 W and an operating power of 75 W.  Based on a
>> power consumption of 75 W, that is 657 kW hr / year of energy. I pay around
>> £0.20 (GBP) per kW hr for electricity, so that's £131 (GBP) annually. I
>> believe electricity is cheaper in the USA than here in the UK, but
>> converting £131 (GBP) to USD, that's around $161/year in electricity.. So
>> running costs don't seem to be an issue.
>> 
>> But I must admit, the thought of spending a lot of time/money to build
>> something I could have bought for a lot less with higher performance is not
>> that attractive, although of course there would be a satisfaction from
>> building it yourself.
>> 
>> Dave
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Re: [time-nuts] hm H Maser

[Poul-Henning Kamp]

In message <619617e1-aa26-4eb7-b73e-042f22912...@n1k.org>, Bob Camp writes:

>I guess the question then would be: 
>
>Is a H Maser that runs 6.6 x 10^-12 at 1 second worth the trouble? 

I would say absolutely not.

All things considered, I think a trapped-ion type standard would
be both much more feasible and much more worth it.

Heck, just getting an optical comb working would be awesome...

-- 
Poul-Henning Kamp   | UNIX since Zilog Zeus 3.20
p...@freebsd.org | TCP/IP since RFC 956
FreeBSD committer   | BSD since 4.3-tahoe
Never attribute to malice what can adequately be explained by incompetence.
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Re: [time-nuts] hm H Maser

[Poul-Henning Kamp]

In message <0C641805E0824C499D3C15F67F0B880B@pc52>, "Tom Van Baak" writes:

>To keep a maser room within 1 C or 0.1 C takes much more power [...]

Forget the power:  Look at the installation costs.

If you want to be able to go in and pat your maser, the air volume
and flow has to be big enough that the 100W heating and increased
humidity you bring does not throw your environment system off balance.

For +/- .5K, you can do that in an existing room.

You need something like 20-40 square meters with about 20cm thermal
insulation in all directions, and a two level 10:1 heat/cool
ventilation kit, capable of handling your local climatic excursions.


For +/- 50mK, building-in-building design is required.

You probably need at least 100 square meters in the interior building
if you want to be able to go in there and stay in tolerance and you
can only stand downwind from the maser at all times.

You will need to think a lot about power fluctuations.  Lightning
must be permanent ON and you may need voltage regulation.  Sunlight
through windows are VerBoten.

You will need a three level 100:10:1 heat/cool A/C setup, and the
":1" level is too big for TECs.  You'll need very competent mixing
(I hope your wife likes the look of the Pompidou center) and even
more competent measurement and regulation.

Building-in-building-in-existing-barn is probably the cheapest you
can do this, and the maser is certainly going to be cheaper.

-- 
Poul-Henning Kamp   | UNIX since Zilog Zeus 3.20
p...@freebsd.org | TCP/IP since RFC 956
FreeBSD committer   | BSD since 4.3-tahoe
Never attribute to malice what can adequately be explained by incompetence.
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Re: [time-nuts] hm H Maser

[Bruce Griffiths]

One could always use a cryo pump.
The following paper is a summary of the current state of the art for rubidium 
vapour frequency 
standards:http://www.euramet.org/Media/docs/Repository/A169/IND55/micalizio_02182015.pdf

Bruce 

On Wednesday, 11 January 2017 5:15 PM, Ole Petter Ronningen 
 wrote:
 

 Add to this ion-pumps (in the case of EFOS type masers 2 every ~2 years),
plus substantial tooling (turbomolecular vacuum pump, anyone?) to service
the thing - unless you want the manufacturer to do so..

Ole

On Tue, Jan 10, 2017 at 11:12 PM, Dr. David Kirkby (Kirkby Microwave Ltd) <
drkir...@kirkbymicrowave.co.uk> wrote:

> On 10 January 2017 at 15:35, Ole Petter Rønningen 
> wrote:
>
> > ... having said that, I for one think I'm with Bob on this one. The thing
> > about masers are that they are big. At least active masers. And they
> > require a substantial volume be kept at ultra high vacuum - which is not
> > trivial, especially not in a homeshop. The cavity needs to be kept at a
> > temperature stable to 0.001 degree C. With 4-5 magnetic shields. Add to
> > this costly pumps to keep the vacuum this low even if you succeed at
> > reaching that vacuum.. There's easily 1-2KUSD running cost per year just
> to
> > keep the maser running.
> >
>
> Looking at the Microsemi MHM 2010 Active Hydogen Maser data sheet, the
> maser has a peak power of 150 W and an operating power of 75 W.  Based on a
> power consumption of 75 W, that is 657 kW hr / year of energy. I pay around
> £0.20 (GBP) per kW hr for electricity, so that's £131 (GBP) annually. I
> believe electricity is cheaper in the USA than here in the UK, but
> converting £131 (GBP) to USD, that's around $161/year in electricity.. So
> running costs don't seem to be an issue.
>
> But I must admit, the thought of spending a lot of time/money to build
> something I could have bought for a lot less with higher performance is not
> that attractive, although of course there would be a satisfaction from
> building it yourself.
>
> Dave
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Re: [time-nuts] hm H Maser

[Ole Petter Ronningen]

Add to this ion-pumps (in the case of EFOS type masers 2 every ~2 years),
plus substantial tooling (turbomolecular vacuum pump, anyone?) to service
the thing - unless you want the manufacturer to do so..

Ole

On Tue, Jan 10, 2017 at 11:12 PM, Dr. David Kirkby (Kirkby Microwave Ltd) <
drkir...@kirkbymicrowave.co.uk> wrote:

> On 10 January 2017 at 15:35, Ole Petter Rønningen 
> wrote:
>
> > ... having said that, I for one think I'm with Bob on this one. The thing
> > about masers are that they are big. At least active masers. And they
> > require a substantial volume be kept at ultra high vacuum - which is not
> > trivial, especially not in a homeshop. The cavity needs to be kept at a
> > temperature stable to 0.001 degree C. With 4-5 magnetic shields. Add to
> > this costly pumps to keep the vacuum this low even if you succeed at
> > reaching that vacuum.. There's easily 1-2KUSD running cost per year just
> to
> > keep the maser running.
> >
>
> Looking at the Microsemi MHM 2010 Active Hydogen Maser data sheet, the
> maser has a peak power of 150 W and an operating power of 75 W.  Based on a
> power consumption of 75 W, that is 657 kW hr / year of energy. I pay around
> £0.20 (GBP) per kW hr for electricity, so that's £131 (GBP) annually. I
> believe electricity is cheaper in the USA than here in the UK, but
> converting £131 (GBP) to USD, that's around $161/year in electricity. So
> running costs don't seem to be an issue.
>
> But I must admit, the thought of spending a lot of time/money to build
> something I could have bought for a lot less with higher performance is not
> that attractive, although of course there would be a satisfaction from
> building it yourself.
>
> Dave
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Re: [time-nuts] hm H Maser

[Bruce Griffiths]

A  spherical cavity resonator with a spherical Rubidium cell configured as an 
integrating sphere (to enhance the SNR of the optical absorption signal) is a 
potential option. Its also possible to use the same cell to lock a 795 nm laser 
to the desired wavelength. Fiber coupling the laser light could also be 
useful.Note that with an integrating sphere (or any other random scattering 
process eg scattering from colloidal particles undergoing Brownian motion) 
laser polarisation isn't preserved which may be convenient.One potential issue 
with an  integrating sphere is the longevity of the diffusing coating 
(typically Barium sulphate with an organic binder). Roughening (fine grind  
followed by HF etch for stress relief) the outer surface of the cell is also 
advisable to eliminate light pipe effects in the cell wall.
Bruce 

On Wednesday, 11 January 2017 3:54 PM, Bruce Griffiths 
 wrote:
 

 A goal with ADEV ~ 1E-13/Tau (for Tau <1000sec) may be feasible as its already 
been done as part of a PhD thesis.Using as large a cavity as possible is 
probably useful so that a large cell can be employed.What resonant mode is 
desirable in the cavity?Do we need to avoid field reversal as in the hydrogen 
maser?
Bruce  

On Wednesday, 11 January 2017 3:43 PM, Bob Camp  wrote:
 

 Hi

I suspect that there are (or will be) some other cheaper / easier ways to do 
the same thing. The signal to noise requirements 
in the RF chain are sensitive to a couple of things, but not to an absurd 
level. You do need good close in noise. I would not even bother to 
go for a “final” RF section until the physics stuff had been worked out. 
Designing today vs designing in a couple
of years will always be the more expensive approach. For the lash up, I might 
well gut parts out of an existing
cheap Rb simply to get things going …. who knows. Maybe we would need a chain 
like the one in the paper to figure out 
what is going on.  In four  years take a look at what is on the market and make 
some decisions about the “final” RF chain. 
Even then you might revisit it several years after that due to cost or 
performance issues….

This does get back to “state of the art Rb” and what that means. In my 
suggested case that’s measured in terms of ADEV for Tau = 1 to 1,000,000 
seconds. If you wanted an Rb with (only) state of the art phase noise at 1 MHz 
offset … that’s a different thing. State of the art for 
power consumption and size is also not what I’m suggesting in this case. Why 
the choice of spec? … this is TimeNuts. 

For some guidance on what state of the art in Rb’s *is* in this area, check out 
the many papers on the GPS Rb’s published in in the ION conference proceedings. 
Can a bunch of hackers do quite that well? … likely not. They have been 
fiddling with that design for many decades. They also have a pretty healthy 
budget to 
produce each one they build. We certainly can try to get as close as we can.. 
Testing ours in orbit *might* put a strain on the budget though :)

Bob

> On Jan 10, 2017, at 9:15 PM, Bruce Griffiths  
> wrote:
> 
> A possible RF chain for a Rubidium standard using off the shelf parts plus a 
> couple of custom microwave filters:https://arxiv.org/pdf/1204.4215.pdf
> 
> Bruce 
> 
>    On Wednesday, 11 January 2017 2:10 PM, Bob Camp  wrote:
> 
> 
> Hi
> 


   

   
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Re: [time-nuts] hm H Maser

[Bob Camp]

Hi

I suspect that there are (or will be) some other cheaper / easier ways to do 
the same thing. The signal to noise requirements 
in the RF chain are sensitive to a couple of things, but not to an absurd 
level. You do need good close in noise. I would not even bother to 
go for a “final” RF section until the physics stuff had been worked out. 
Designing today vs designing in a couple
of years will always be the more expensive approach. For the lash up, I might 
well gut parts out of an existing
cheap Rb simply to get things going …. who knows. Maybe we would need a chain 
like the one in the paper to figure out 
what is going on.  In four  years take a look at what is on the market and make 
some decisions about the “final” RF chain. 
Even then you might revisit it several years after that due to cost or 
performance issues….

This does get back to “state of the art Rb” and what that means. In my 
suggested case that’s measured in terms of ADEV for Tau = 1 to 1,000,000 
seconds. If you wanted an Rb with (only) state of the art phase noise at 1 MHz 
offset … that’s a different thing. State of the art for 
power consumption and size is also not what I’m suggesting in this case. Why 
the choice of spec? … this is TimeNuts. 

For some guidance on what state of the art in Rb’s *is* in this area, check out 
the many papers on the GPS Rb’s published in in the ION conference proceedings. 
Can a bunch of hackers do quite that well? … likely not. They have been 
fiddling with that design for many decades. They also have a pretty healthy 
budget to 
produce each one they build. We certainly can try to get as close as we can. 
Testing ours in orbit *might* put a strain on the budget though :)

Bob

> On Jan 10, 2017, at 9:15 PM, Bruce Griffiths  
> wrote:
> 
> A possible RF chain for a Rubidium standard using off the shelf parts plus a 
> couple of custom microwave filters:https://arxiv.org/pdf/1204.4215.pdf
> 
> Bruce 
> 
>On Wednesday, 11 January 2017 2:10 PM, Bob Camp  wrote:
> 
> 
> Hi
> 

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Re: [time-nuts] hm H Maser

[Bruce Griffiths]

A possible RF chain for a Rubidium standard using off the shelf parts plus a 
couple of custom microwave filters:https://arxiv.org/pdf/1204.4215.pdf

Bruce 

On Wednesday, 11 January 2017 2:10 PM, Bob Camp  wrote:
 

 Hi

The gotcha is that 5065’s never were a popular item in HP’s lineup. As a 
result, they are fairly sparse in the surplus market. Those who need them
for this or that application gobble them up on a regular basis. Trying to do 
up a couple hundred “improved” 5065’s just isn’t going to happen (at least 
without driving the current price up by > 10X or 100X). 

Since about the only thing you keep from the 5065 once you are done is the
physics package, that’s a big payout for very few usable parts. You then 
modify (and possibly repair) the physics package. If we ever get into this, you
also replace a few parts in there to improve it’s performance. Now you have
even fewer “keeper” parts. 

Simple approach:

Decide you want a state of the art Rb (what other goal would there be?) 
Organize the team
Work out a first pass design
Find a source for *large* Rb cell sets.
Work with them to get the cells right
Design up a physics package in parallel with this effort
Get it all prototyped multiple times and debugged with lash up electronics
Test for about a year once you have the prototype debugged
Order up the tooling on the long lead stuff (cells and some machined parts)
Get the real electronics working in some form
Debug the electronics against the real cells and parts
Test for about a year once you think it’s working
Do the real layouts and packaging, including shielding and all the other nasty 
stuff
Fit up the first unit 
Test for about a year to be sure you have caught all the issues
Redo what is needed
Start building the hundred or so units on order with the cash on hand from 
those orders.

Lots of fun !!

I’m sure somebody will chime in at this point and claim they can do that all 
for about $100 a unit. If so feel free to try. It’s simply liars poker at that 
point
since nobody ever has to actually do it. Based on having done it and on having
seen others do it … it is not at all cheap to do. Rb *is* cheaper, but it’s 
still not free. 

You might also question the “test for a year” stuff. If you want ADEV style 
data that has
any meaning, you need sample sizes that are in the 10 to 100X tau range. For a 
one
week tau, each run will be > 3 months.  Testing takes time…..You also need to be
testing multiple units to get any confidence. That takes money.

Even more fun.

Bob


> On Jan 10, 2017, at 7:40 PM, Gregory Maxwell  wrote:
> 
> On Wed, Jan 11, 2017 at 12:25 AM, Bob kb8tq  wrote:
>> I have a pile of stuff. You have a pile of stuff. Others each have their 
>> pile of stuff. Doing
>> a design that works only with my pile is possible. Doing a design that works 
>> with my pile
> [...]
>> You have to do it with a fairly standardized
>> design. That means buying (at the very least) kits of parts. Like it or not, 
>> the parts kit for a
>> Rb will be cheaper than the parts kit for any of the other devices…..
> 
> I read the occasional posts by PHK on his efforts to upgrade the
> electronics in his 5065a and Corby's SUPER physics package upgrade
> with great interest.  I have wondered if the end result may be that
> incremental upgrades to someone elses classic design, adding on modern
> synthesizers and digital control, etc. Might eventually result in a
> 'Ship of Theseus' oscillator, which in its final form is buildable
> from relatively easily sourced parts (plus perhaps a rubidium cell
> that could be group bought at non-absurd prices).
> 
> Presumably taking an already established design and improving it
> incrementally has lower risk and costs than a new design. In
> particular, it can start off with 5065a as "my pile" inputs, but by
> the end it doesn't have them anymore... and not just lest risky but
> also a more natural way to divide the effort up into less
> professionally-sized chunks.
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Re: [time-nuts] hm H Maser

[Bob Camp]

Hi

The gotcha is that 5065’s never were a popular item in HP’s lineup. As a 
result, they are fairly sparse in the surplus market. Those who need them
for this or that application gobble them up on a regular basis. Trying to do 
up a couple hundred “improved” 5065’s just isn’t going to happen (at least 
without driving the current price up by > 10X or 100X). 

Since about the only thing you keep from the 5065 once you are done is the
physics package, that’s a big payout for very few usable parts. You then 
modify (and possibly repair) the physics package. If we ever get into this, you
also replace a few parts in there to improve it’s performance. Now you have
even fewer “keeper” parts. 

Simple approach:

Decide you want a state of the art Rb (what other goal would there be?) 
Organize the team
Work out a first pass design
Find a source for *large* Rb cell sets.
Work with them to get the cells right
Design up a physics package in parallel with this effort
Get it all prototyped multiple times and debugged with lash up electronics
Test for about a year once you have the prototype debugged
Order up the tooling on the long lead stuff (cells and some machined parts)
Get the real electronics working in some form
Debug the electronics against the real cells and parts
Test for about a year once you think it’s working
Do the real layouts and packaging, including shielding and all the other nasty 
stuff
Fit up the first unit 
Test for about a year to be sure you have caught all the issues
Redo what is needed
Start building the hundred or so units on order with the cash on hand from 
those orders.

Lots of fun !!

I’m sure somebody will chime in at this point and claim they can do that all 
for about $100 a unit. If so feel free to try. It’s simply liars poker at that 
point
since nobody ever has to actually do it. Based on having done it and on having
seen others do it … it is not at all cheap to do. Rb *is* cheaper, but it’s 
still not free. 

You might also question the “test for a year” stuff. If you want ADEV style 
data that has
any meaning, you need sample sizes that are in the 10 to 100X tau range. For a 
one
week tau, each run will be > 3 months.  Testing takes time…..You also need to be
testing multiple units to get any confidence. That takes money.

Even more fun.

Bob


> On Jan 10, 2017, at 7:40 PM, Gregory Maxwell  wrote:
> 
> On Wed, Jan 11, 2017 at 12:25 AM, Bob kb8tq  wrote:
>> I have a pile of stuff. You have a pile of stuff. Others each have their 
>> pile of stuff. Doing
>> a design that works only with my pile is possible. Doing a design that works 
>> with my pile
> [...]
>> You have to do it with a fairly standardized
>> design. That means buying (at the very least) kits of parts. Like it or not, 
>> the parts kit for a
>> Rb will be cheaper than the parts kit for any of the other devices…..
> 
> I read the occasional posts by PHK on his efforts to upgrade the
> electronics in his 5065a and Corby's SUPER physics package upgrade
> with great interest.  I have wondered if the end result may be that
> incremental upgrades to someone elses classic design, adding on modern
> synthesizers and digital control, etc. Might eventually result in a
> 'Ship of Theseus' oscillator, which in its final form is buildable
> from relatively easily sourced parts (plus perhaps a rubidium cell
> that could be group bought at non-absurd prices).
> 
> Presumably taking an already established design and improving it
> incrementally has lower risk and costs than a new design. In
> particular, it can start off with 5065a as "my pile" inputs, but by
> the end it doesn't have them anymore... and not just lest risky but
> also a more natural way to divide the effort up into less
> professionally-sized chunks.
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Re: [time-nuts] hm H Maser

[Gregory Maxwell]

On Wed, Jan 11, 2017 at 12:25 AM, Bob kb8tq  wrote:
> I have a pile of stuff. You have a pile of stuff. Others each have their pile 
> of stuff. Doing
> a design that works only with my pile is possible. Doing a design that works 
> with my pile
[...]
> You have to do it with a fairly standardized
> design. That means buying (at the very least) kits of parts. Like it or not, 
> the parts kit for a
> Rb will be cheaper than the parts kit for any of the other devices…..

I read the occasional posts by PHK on his efforts to upgrade the
electronics in his 5065a and Corby's SUPER physics package upgrade
with great interest.  I have wondered if the end result may be that
incremental upgrades to someone elses classic design, adding on modern
synthesizers and digital control, etc. Might eventually result in a
'Ship of Theseus' oscillator, which in its final form is buildable
from relatively easily sourced parts (plus perhaps a rubidium cell
that could be group bought at non-absurd prices).

Presumably taking an already established design and improving it
incrementally has lower risk and costs than a new design. In
particular, it can start off with 5065a as "my pile" inputs, but by
the end it doesn't have them anymore... and not just lest risky but
also a more natural way to divide the effort up into less
professionally-sized chunks.
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Re: [time-nuts] hm H Maser

[Bob kb8tq]

Hi

Masers pop up in good (as in new or almost so) condition in the $30 to $70K 
range from time to time. You *do* need to be a bit lucky, but compared to a 
decade
long development process … not very lucky. The biggest issue with Masers is 
that there
isn’t much of a market. They simply are to expensive for what they do. Neat 
devices 
most certainly. I’d love to have several of them. Selling the house to buy 
several, is not
going to go over well with the rest of the family …..

One point about this that is a bit significant:

I have a pile of stuff. You have a pile of stuff. Others each have their pile 
of stuff. Doing
a design that works only with my pile is possible. Doing a design that works 
with my pile
and your pile is unlikely. Doing one that works with all the piles is 
impossible. If I sit here and 
decide that my pile is the only one that matters, I then conclude that others 
should put a few 
(hundred) man-years into making it all work. That’s nonsense. The only rational 
project that
others will toss in a decade of time to is one where they each get a device as 
a result. You
can’t do that with my pile / your pile / all the piles. You have to do it with 
a fairly standardized
design. That means buying (at the very least) kits of parts. Like it or not, 
the parts kit for a
Rb will be cheaper than the parts kit for any of the other devices…..

Bob

> On Jan 10, 2017, at 6:24 PM, paul swed  wrote:
> 
> I have enjoyed reading the thread and learned a bit. But given some of the
> other threads I have read on improving RBs and CS's don't they make more
> sense for most Time Nuts. I mean the conversations in the $100K and above
> and outside of being fun to read doesn't make sense at all.
> If I had $100K I would buy a new CS or slightly worn and save the rest...
> 
> There is a very real aspect of the conversation thats very interesting. Say
> you are building a maser thats as good as a C or maybe not quite. The fact
> that it can be refilled does give the system a very very long life. What
> opportunity does this give you in simplifying the design and cost? What is
> the thing thats driving up the cost?
> Hex pole magnets, the cavity
> 
> Regards
> Paul.
> WB8TSL
> 
> 
> 
> 
> 

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Re: [time-nuts] hm H Maser

[Tom Van Baak]

> Looking at the Microsemi MHM 2010 Active Hydogen Maser data sheet, the
> maser has a peak power of 150 W and an operating power of 75 W.  Based on a
> power consumption of 75 W, that is 657 kW hr / year of energy. I pay around
> £0.20 (GBP) per kW hr for electricity, so that's £131 (GBP) annually. I
> believe electricity is cheaper in the USA than here in the UK, but
> converting £131 (GBP) to USD, that's around $161/year in electricity. So
> running costs don't seem to be an issue.

Dave,

The cost of the lab and the cost of A/C must also be factored in. To keep a 
maser room within 1 C or 0.1 C takes much more power than the maser itself. Add 
to that the power consumed by the UPS(s) and all the other support 
instrumentation required to tend to a maser and it adds up, in both power and 
money.

Ole's estimate of 1-2k/yr is much closer to the truth than your $161/yr.

/tvb
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Re: [time-nuts] hm H Maser

[paul swed]

I have enjoyed reading the thread and learned a bit. But given some of the
other threads I have read on improving RBs and CS's don't they make more
sense for most Time Nuts. I mean the conversations in the $100K and above
and outside of being fun to read doesn't make sense at all.
If I had $100K I would buy a new CS or slightly worn and save the rest...

There is a very real aspect of the conversation thats very interesting. Say
you are building a maser thats as good as a C or maybe not quite. The fact
that it can be refilled does give the system a very very long life. What
opportunity does this give you in simplifying the design and cost? What is
the thing thats driving up the cost?
Hex pole magnets, the cavity

Regards
Paul.
WB8TSL





On Tue, Jan 10, 2017 at 6:02 PM, Bob kb8tq <kb...@n1k.org> wrote:

> Hi
>
> > On Jan 10, 2017, at 5:26 PM, Bob Stewart <b...@evoria.net> wrote:
> >
> > This may be a dumb question, but how much of an H Maser's advantage over
> a Cs Standard, for us mere mortal time-nuts, is down to the output
> oscillator it uses, rather than the reference source (H MASER or Cs beam)?
>
> Pretty much none. You *can* design one with a crummy OCXO, but the
> question becomes - why would you do that? Putting a $10,000 OCXO into a
> $150K device is not that big a deal. If you put the same OCXO into a Cs
> standard, it would run a bit better out to the cross over point (a few 100
> seconds or so). Indeed *some* Cs standards have such OCXO’s in them and
> that’s what they do.
>
> Bob
>
> > Bob
> >
> >  From: Dr. David Kirkby (Kirkby Microwave Ltd) <
> drkir...@kirkbymicrowave.co.uk>
> > To: Discussion of precise time and frequency measurement <
> time-nuts@febo.com>
> > Sent: Tuesday, January 10, 2017 4:12 PM
> > Subject: Re: [time-nuts] hm H Maser
> >
> > On 10 January 2017 at 15:35, Ole Petter Rønningen <opronnin...@gmail.com
> >
> > wrote:
> >
> >> ... having said that, I for one think I'm with Bob on this one. The
> thing
> >> about masers are that they are big. At least active masers. And they
> >> require a substantial volume be kept at ultra high vacuum - which is not
> >> trivial, especially not in a homeshop. The cavity needs to be kept at a
> >> temperature stable to 0.001 degree C. With 4-5 magnetic shields. Add to
> >> this costly pumps to keep the vacuum this low even if you succeed at
> >> reaching that vacuum.. There's easily 1-2KUSD running cost per year
> just to
> >> keep the maser running.
> >>
> >
> > Looking at the Microsemi MHM 2010 Active Hydogen Maser data sheet, the
> > maser has a peak power of 150 W and an operating power of 75 W.  Based
> on a
> > power consumption of 75 W, that is 657 kW hr / year of energy. I pay
> around
> > £0.20 (GBP) per kW hr for electricity, so that's £131 (GBP) annually. I
> > believe electricity is cheaper in the USA than here in the UK, but
> > converting £131 (GBP) to USD, that's around $161/year in electricity. So
> > running costs don't seem to be an issue.
> >
> > But I must admit, the thought of spending a lot of time/money to build
> > something I could have bought for a lot less with higher performance is
> not
> > that attractive, although of course there would be a satisfaction from
> > building it yourself.
> >
> > Dave
> > ___
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> > 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] hm H Maser

[Bob kb8tq]

Hi

> On Jan 10, 2017, at 5:26 PM, Bob Stewart <b...@evoria.net> wrote:
> 
> This may be a dumb question, but how much of an H Maser's advantage over a Cs 
> Standard, for us mere mortal time-nuts, is down to the output oscillator it 
> uses, rather than the reference source (H MASER or Cs beam)?

Pretty much none. You *can* design one with a crummy OCXO, but the question 
becomes - why would you do that? Putting a $10,000 OCXO into a $150K device is 
not that big a deal. If you put the same OCXO into a Cs standard, it would run 
a bit better out to the cross over point (a few 100 seconds or so). Indeed 
*some* Cs standards have such OCXO’s in them and that’s what they do. 

Bob

> Bob
> 
>  From: Dr. David Kirkby (Kirkby Microwave Ltd) 
> <drkir...@kirkbymicrowave.co.uk>
> To: Discussion of precise time and frequency measurement <time-nuts@febo.com> 
> Sent: Tuesday, January 10, 2017 4:12 PM
> Subject: Re: [time-nuts] hm H Maser
> 
> On 10 January 2017 at 15:35, Ole Petter Rønningen <opronnin...@gmail.com>
> wrote:
> 
>> ... having said that, I for one think I'm with Bob on this one. The thing
>> about masers are that they are big. At least active masers. And they
>> require a substantial volume be kept at ultra high vacuum - which is not
>> trivial, especially not in a homeshop. The cavity needs to be kept at a
>> temperature stable to 0.001 degree C. With 4-5 magnetic shields. Add to
>> this costly pumps to keep the vacuum this low even if you succeed at
>> reaching that vacuum.. There's easily 1-2KUSD running cost per year just to
>> keep the maser running.
>> 
> 
> Looking at the Microsemi MHM 2010 Active Hydogen Maser data sheet, the
> maser has a peak power of 150 W and an operating power of 75 W.  Based on a
> power consumption of 75 W, that is 657 kW hr / year of energy. I pay around
> £0.20 (GBP) per kW hr for electricity, so that's £131 (GBP) annually. I
> believe electricity is cheaper in the USA than here in the UK, but
> converting £131 (GBP) to USD, that's around $161/year in electricity. So
> running costs don't seem to be an issue.
> 
> But I must admit, the thought of spending a lot of time/money to build
> something I could have bought for a lot less with higher performance is not
> that attractive, although of course there would be a satisfaction from
> building it yourself.
> 
> Dave
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> 
> 
> 
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Re: [time-nuts] hm H Maser

[Bob Stewart]

This may be a dumb question, but how much of an H Maser's advantage over a Cs 
Standard, for us mere mortal time-nuts, is down to the output oscillator it 
uses, rather than the reference source (H MASER or Cs beam)?
Bob

  From: Dr. David Kirkby (Kirkby Microwave Ltd) 
<drkir...@kirkbymicrowave.co.uk>
 To: Discussion of precise time and frequency measurement <time-nuts@febo.com> 
 Sent: Tuesday, January 10, 2017 4:12 PM
 Subject: Re: [time-nuts] hm H Maser
   
On 10 January 2017 at 15:35, Ole Petter Rønningen <opronnin...@gmail.com>
wrote:

> ... having said that, I for one think I'm with Bob on this one. The thing
> about masers are that they are big. At least active masers. And they
> require a substantial volume be kept at ultra high vacuum - which is not
> trivial, especially not in a homeshop. The cavity needs to be kept at a
> temperature stable to 0.001 degree C. With 4-5 magnetic shields. Add to
> this costly pumps to keep the vacuum this low even if you succeed at
> reaching that vacuum.. There's easily 1-2KUSD running cost per year just to
> keep the maser running.
>

Looking at the Microsemi MHM 2010 Active Hydogen Maser data sheet, the
maser has a peak power of 150 W and an operating power of 75 W.  Based on a
power consumption of 75 W, that is 657 kW hr / year of energy. I pay around
£0.20 (GBP) per kW hr for electricity, so that's £131 (GBP) annually. I
believe electricity is cheaper in the USA than here in the UK, but
converting £131 (GBP) to USD, that's around $161/year in electricity. So
running costs don't seem to be an issue.

But I must admit, the thought of spending a lot of time/money to build
something I could have bought for a lot less with higher performance is not
that attractive, although of course there would be a satisfaction from
building it yourself.

Dave
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Re: [time-nuts] hm H Maser

[Dr. David Kirkby (Kirkby Microwave Ltd)]

On 10 January 2017 at 15:35, Ole Petter Rønningen 
wrote:

> ... having said that, I for one think I'm with Bob on this one. The thing
> about masers are that they are big. At least active masers. And they
> require a substantial volume be kept at ultra high vacuum - which is not
> trivial, especially not in a homeshop. The cavity needs to be kept at a
> temperature stable to 0.001 degree C. With 4-5 magnetic shields. Add to
> this costly pumps to keep the vacuum this low even if you succeed at
> reaching that vacuum.. There's easily 1-2KUSD running cost per year just to
> keep the maser running.
>

Looking at the Microsemi MHM 2010 Active Hydogen Maser data sheet, the
maser has a peak power of 150 W and an operating power of 75 W.  Based on a
power consumption of 75 W, that is 657 kW hr / year of energy. I pay around
£0.20 (GBP) per kW hr for electricity, so that's £131 (GBP) annually. I
believe electricity is cheaper in the USA than here in the UK, but
converting £131 (GBP) to USD, that's around $161/year in electricity. So
running costs don't seem to be an issue.

But I must admit, the thought of spending a lot of time/money to build
something I could have bought for a lot less with higher performance is not
that attractive, although of course there would be a satisfaction from
building it yourself.

Dave
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Re: [time-nuts] hm H Maser

[Javier Herrero]

Hello,

Two kind of clocks were developed and qualified, a Rb and the PHM, and 
it seems that this is the cost for the development of both (since it 
mentions two on-board clock technologies). And this includes the 
development of breadboards (EBBs, really full-fledged prototypes with no 
qualified parts) and of qualification models ( 
http://www.spectratime.com/uploads/documents/ispace/PTTI_FCS_RAFS_PHM_2005.pdf 
), designed and manufactured with flight-quality components since the 
EQMs are submitted to all testing (thermal vacuum, vibration, life, 
EMC...) to levels a lot more estringent than those applicable for a 
commercial-use maser.


Taking into account that GIOVE-B (used as the in-flight test bed for the 
PHM) cost was 72M€, surely excluding launch and deployment costs, I 
suppose that excluding the PHM itself, it seem that 100M€ is the order 
of magnitude for the development including in-flight testing platform.


Regards,

Javier


On 10/01/2017 17:22, Ole Petter Rønningen wrote:

"The European Commission and the European Space Agency have approved the Galileo 
GNSS programme. Two experimental satellites will be launched in late 2005 or early 2006. 
Atomic clocks are critical for satellite navigation. After more than ten years of 
development and an overall budget of € 30M, two onboard clock technologies have been 
qualified. The author considers their current status and performance."

https://www.gim-international.com/content/article/onboard-galileo-atomic-clocks

Ole


Den 10. jan. 2017 kl. 14.18 skrev ewkehren via time-nuts :

Do we know what the PHM development for Galileo cost?




Sent from Samsung tabletBob Camp  wrote:Hi


On Jan 10, 2017, at 2:45 AM, Dr. David Kirkby (Kirkby Microwave Ltd) 
 wrote:

Once 9 Jan 2017 12:59, "Bob Camp"  wrote:

Hi

Ok here are some rough numbers:


On Jan 9, 2017, at 4:35 AM, Dr. David Kirkby (Kirkby Microwave Ltd) <

drkir...@kirkbymicrowave.co.uk> wrote:


It would be interesting to see your breakdown of the costs and man hours
for an H2 maser. I suspect that others would find cheaper/faster

solutions.

$100M for the H2

$25M for the Rb

With all due respect,  and I apprectiate you have a good knowledge of this
field, but that's not a breakdown of costs or man hours I wanted to see,
but a cost which appears to be plucked from the air.

Hardly plucked from the air. The last Rb design that I was involved with was
roughly 5X that expensive.


There's a BIG difference between a volunteer effort where

* Salaries are not paid
* Items of test equipment are likely to be borrowed or people provide
access to them for no charge etc,
* Academics are likely to provide consultancy for free, in return for being
on papers published.
* Software licenses could probably be obtained free,  or enough people get
trials.

That’s where the 5:1 cost reduction comes from.


compared to a commercial company building a maser where

* Salaries are paid
* All equipment is purchased new
* Bench power supplies with 3.5 digit displays are sent out for calibration
each year.
*  No outside body will do anything except at a commercial rate.
* Flights are booked for meetings which could be done over the Internet.
* High end software licenses are huge.


$500M for the fountain.

But on what basis do you arrive at that figure?

The numbers that the people who have done it come up with when you talk to them.


To get sponsorship for anything remotely close to those numbers, you
need to have some massively good credentials.

Bob

Yes agreed at $500M. But someone like Tom, who does have massively good
credentials, could perhaps get $500,000, and perhaps that wisely spent
could get a fountain built.  Without knowing how you arrive at $500M, it is
not possible for anyone to look at ways of shaving that cost.


This is *not* a cheap field to be doing things in ….

Bob


The Lovell Telescope at Jodrell Bank in the UK was built on a shoestring
budget. It was at the time the world's  largest steerable radio telephone.
Half a century later only 2 larger ones have been built.

Maybe I am too nieve.

Dave.
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Re: [time-nuts] hm H Maser

[William H. Fite]

On Tuesday, January 10, 2017, jimlux  wrote:



>
> This fits in the bucket of a cross-disciplinary project, like building a
> fusor, or a pulsed TEA laser, a Bose-Einstein Condensate generator, or any
> of a variety of similar projects.


Or a Lazar gravity warp generator.

>
> You can almost always find a commercial solution that can do it
> better/cheaper/more reliably - but the learning experience is valuable. I
> have almost zero desire to fool with high vacuum systems again, but the
> time I did it, I learned a lot.
>
>
>
> And t
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-- 
If you gaze long into an abyss, your coffee will get cold.
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Re: [time-nuts] hm H Maser

[jimlux]

On 1/10/17 7:35 AM, Ole Petter Rønningen wrote:

... having said that, I for one think I'm with Bob on this one. The
thing about masers are that they are big. At least active masers. And
they require a substantial volume be kept at ultra high vacuum -
which is not trivial, especially not in a homeshop. The cavity needs
to be kept at a temperature stable to 0.001 degree C. With 4-5
magnetic shields. Add to this costly pumps to keep the vacuum this
low even if you succeed at reaching that vacuum.. There's easily
1-2KUSD running cost per year just to keep the maser running.


Lots of people spend $4/day on coffee.. that's $1200/yr..
I'd give up a cup of coffee to run a AHM 




Granted, I've never built a maser, but personally I think the
problems that would need to solving (and lead to learning) would be
much more on the vacuum-systems, shielding and temperature long
before electronics becomes a major factor.


This fits in the bucket of a cross-disciplinary project, like building a 
fusor, or a pulsed TEA laser, a Bose-Einstein Condensate generator, or 
any of a variety of similar projects.


You can almost always find a commercial solution that can do it 
better/cheaper/more reliably - but the learning experience is valuable. 
I have almost zero desire to fool with high vacuum systems again, but 
the time I did it, I learned a lot.




And the chance of

actually get a result comparable to a commercial maser (or even just
better than what you could realistically pick up from ebay for a few
K) are pretty slim. And LOT of time and cash would be burned before
you are even close to getting some sort of oscillation.

A rubidium does look like a more realistic project..

Dont get me wrong - it would be beyond cool if someone built a
homemade maser. The first ones were built by regular people in
regular labs, so sure it can be done.


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Re: [time-nuts] hm H Maser

[Ole Petter Rønningen]

"The European Commission and the European Space Agency have approved the 
Galileo GNSS programme. Two experimental satellites will be launched in late 
2005 or early 2006. Atomic clocks are critical for satellite navigation. After 
more than ten years of development and an overall budget of € 30M, two onboard 
clock technologies have been qualified. The author considers their current 
status and performance."

https://www.gim-international.com/content/article/onboard-galileo-atomic-clocks

Ole

> Den 10. jan. 2017 kl. 14.18 skrev ewkehren via time-nuts :
> 
> Do we know what the PHM development for Galileo cost?
> 
> 
> 
> 
> Sent from Samsung tabletBob Camp  wrote:Hi
> 
>> On Jan 10, 2017, at 2:45 AM, Dr. David Kirkby (Kirkby Microwave Ltd) 
>>  wrote:
>> 
>> Once 9 Jan 2017 12:59, "Bob Camp"  wrote:
>>> 
>>> Hi
>>> 
>>> Ok here are some rough numbers:
>>> 
 On Jan 9, 2017, at 4:35 AM, Dr. David Kirkby (Kirkby Microwave Ltd) <
>> drkir...@kirkbymicrowave.co.uk> wrote:
>> 
 It would be interesting to see your breakdown of the costs and man hours
 for an H2 maser. I suspect that others would find cheaper/faster
>> solutions.
>>> 
>>> $100M for the H2
>>> 
>>> $25M for the Rb
>> 
>> With all due respect,  and I apprectiate you have a good knowledge of this
>> field, but that's not a breakdown of costs or man hours I wanted to see,
>> but a cost which appears to be plucked from the air.
> 
> Hardly plucked from the air. The last Rb design that I was involved with was 
> roughly 5X that expensive. 
> 
>> 
>> There's a BIG difference between a volunteer effort where
>> 
>> * Salaries are not paid
>> * Items of test equipment are likely to be borrowed or people provide
>> access to them for no charge etc,
>> * Academics are likely to provide consultancy for free, in return for being
>> on papers published.
>> * Software licenses could probably be obtained free,  or enough people get
>> trials.
> 
> That’s where the 5:1 cost reduction comes from. 
> 
>> 
>> compared to a commercial company building a maser where
>> 
>> * Salaries are paid
>> * All equipment is purchased new
>> * Bench power supplies with 3.5 digit displays are sent out for calibration
>> each year.
>> *  No outside body will do anything except at a commercial rate.
>> * Flights are booked for meetings which could be done over the Internet.
>> * High end software licenses are huge.
>> 
>>> $500M for the fountain.
>> 
>> But on what basis do you arrive at that figure?
> 
> The numbers that the people who have done it come up with when you talk to 
> them. 
> 
>> 
>>> To get sponsorship for anything remotely close to those numbers, you
>>> need to have some massively good credentials.
>>> 
>>> Bob
>> 
>> Yes agreed at $500M. But someone like Tom, who does have massively good
>> credentials, could perhaps get $500,000, and perhaps that wisely spent
>> could get a fountain built.  Without knowing how you arrive at $500M, it is
>> not possible for anyone to look at ways of shaving that cost.
> 
> 
> This is *not* a cheap field to be doing things in ….
> 
> Bob
> 
>> 
>> The Lovell Telescope at Jodrell Bank in the UK was built on a shoestring
>> budget. It was at the time the world's  largest steerable radio telephone.
>> Half a century later only 2 larger ones have been built.
>> 
>> Maybe I am too nieve.
>> 
>> Dave.
>> ___
>> 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] hm H Maser

[Ole Petter Rønningen]

... having said that, I for one think I'm with Bob on this one. The thing about 
masers are that they are big. At least active masers. And they require a 
substantial volume be kept at ultra high vacuum - which is not trivial, 
especially not in a homeshop. The cavity needs to be kept at a temperature 
stable to 0.001 degree C. With 4-5 magnetic shields. Add to this costly pumps 
to keep the vacuum this low even if you succeed at reaching that vacuum.. 
There's easily 1-2KUSD running cost per year just to keep the maser running.

Granted, I've never built a maser, but personally I think the problems that 
would need to solving (and lead to learning) would be much more on the 
vacuum-systems, shielding and temperature long before electronics becomes a 
major factor. And the chance of  actually get a result comparable to a 
commercial maser (or even just better than what you could realistically pick up 
from ebay for a few K) are pretty slim. And LOT of time and cash would be 
burned before you are even close to getting some sort of oscillation.

A rubidium does look like a more realistic project.. 

Dont get me wrong - it would be beyond cool if someone built a homemade maser. 
The first ones were built by regular people in regular labs, so sure it can be 
done.

Well, my $0.02 has been spent..
Ole

> Den 10. jan. 2017 kl. 15.15 skrev Ole Petter Ronningen 
> :
> 
> Not sure how relevant that particular example is. PHM on Galileo was new 
> science (at least the sapphire loaded cavity), and *very* different 
> reliability engineering.
> 
> AHM's are nothing new, the science hace been done, the construction is known, 
> down to exact drawings and circuit diagrams. There are numbers from 1982 that 
> can possibly be used as a startingpoint for estimating an amateur project in 
> https://library.nrao.edu/public/memos/vlba/main/VLBA_65.pdf
> 
> As a side note, I am also not convinced that sourcing the fused quartz teflon 
> coated bulbs would be a show stopper for a limited number (<5) of masers, I 
> for one have one on my shelf. It is quite possible that old bulbs for 
> previous designs exists with the current manufacturers that they might be 
> willing to part with.
> 
> They are also still manufactured, Vremya or one of the others might be 
> willing to sell them - although I have no idea about the cost.
> 
> As another side note, on a trip to Switzerland I was allowed a glimpse of a 
> couple of the PHM's for Galileo in person. Impressive. 
> 
> Ole
> 
>> On Tue, Jan 10, 2017 at 2:18 PM, ewkehren via time-nuts  
>> wrote:
>> Do we know what the PHM development for Galileo cost?
>> 
>> 
>> 
>> 
>> Sent from Samsung tabletBob Camp  wrote:Hi
>> 
>> > On Jan 10, 2017, at 2:45 AM, Dr. David Kirkby (Kirkby Microwave Ltd) 
>> >  wrote:
>> >
>> > Once 9 Jan 2017 12:59, "Bob Camp"  wrote:
>> >>
>> >> Hi
>> >>
>> >> Ok here are some rough numbers:
>> >>
>> >>> On Jan 9, 2017, at 4:35 AM, Dr. David Kirkby (Kirkby Microwave Ltd) <
>> > drkir...@kirkbymicrowave.co.uk> wrote:
>> >
>> >>> It would be interesting to see your breakdown of the costs and man hours
>> >>> for an H2 maser. I suspect that others would find cheaper/faster
>> > solutions.
>> >>
>> >> $100M for the H2
>> >>
>> >> $25M for the Rb
>> >
>> > With all due respect,  and I apprectiate you have a good knowledge of this
>> > field, but that's not a breakdown of costs or man hours I wanted to see,
>> > but a cost which appears to be plucked from the air.
>> 
>> Hardly plucked from the air. The last Rb design that I was involved with was
>> roughly 5X that expensive.
>> 
>> >
>> > There's a BIG difference between a volunteer effort where
>> >
>> > * Salaries are not paid
>> > * Items of test equipment are likely to be borrowed or people provide
>> > access to them for no charge etc,
>> > * Academics are likely to provide consultancy for free, in return for being
>> > on papers published.
>> > * Software licenses could probably be obtained free,  or enough people get
>> > trials.
>> 
>> That’s where the 5:1 cost reduction comes from.
>> 
>> >
>> > compared to a commercial company building a maser where
>> >
>> > * Salaries are paid
>> > * All equipment is purchased new
>> > * Bench power supplies with 3.5 digit displays are sent out for calibration
>> > each year.
>> > *  No outside body will do anything except at a commercial rate.
>> > * Flights are booked for meetings which could be done over the Internet.
>> > * High end software licenses are huge.
>> >
>> >> $500M for the fountain.
>> >
>> > But on what basis do you arrive at that figure?
>> 
>> The numbers that the people who have done it come up with when you talk to 
>> them.
>> 
>> >
>> >> To get sponsorship for anything remotely close to those numbers, you
>> >> need to have some massively good credentials.
>> >>
>> >> Bob
>> >
>> > Yes agreed at $500M. But someone like Tom, who does have 

Re: [time-nuts] hm H Maser

[Ole Petter Ronningen]

Not sure how relevant that particular example is. PHM on Galileo was new
science (at least the sapphire loaded cavity), and *very* different
reliability engineering.

AHM's are nothing new, the science hace been done, the construction is
known, down to exact drawings and circuit diagrams. There are numbers from
1982 that can possibly be used as a startingpoint for estimating an amateur
project in https://library.nrao.edu/public/memos/vlba/main/VLBA_65.pdf

As a side note, I am also not convinced that sourcing the fused quartz
teflon coated bulbs would be a show stopper for a limited number (<5) of
masers, I for one have one on my shelf. It is quite possible that old bulbs
for previous designs exists with the current manufacturers that they might
be willing to part with.

They are also still manufactured, Vremya or one of the others might be
willing to sell them - although I have no idea about the cost.

As another side note, on a trip to Switzerland I was allowed a glimpse of a
couple of the PHM's for Galileo in person. Impressive.

Ole

On Tue, Jan 10, 2017 at 2:18 PM, ewkehren via time-nuts 
wrote:

> Do we know what the PHM development for Galileo cost?
>
>
>
>
> Sent from Samsung tabletBob Camp  wrote:Hi
>
> > On Jan 10, 2017, at 2:45 AM, Dr. David Kirkby (Kirkby Microwave Ltd) <
> drkir...@kirkbymicrowave.co.uk> wrote:
> >
> > Once 9 Jan 2017 12:59, "Bob Camp"  wrote:
> >>
> >> Hi
> >>
> >> Ok here are some rough numbers:
> >>
> >>> On Jan 9, 2017, at 4:35 AM, Dr. David Kirkby (Kirkby Microwave Ltd) <
> > drkir...@kirkbymicrowave.co.uk> wrote:
> >
> >>> It would be interesting to see your breakdown of the costs and man
> hours
> >>> for an H2 maser. I suspect that others would find cheaper/faster
> > solutions.
> >>
> >> $100M for the H2
> >>
> >> $25M for the Rb
> >
> > With all due respect,  and I apprectiate you have a good knowledge of
> this
> > field, but that's not a breakdown of costs or man hours I wanted to see,
> > but a cost which appears to be plucked from the air.
>
> Hardly plucked from the air. The last Rb design that I was involved with
> was
> roughly 5X that expensive.
>
> >
> > There's a BIG difference between a volunteer effort where
> >
> > * Salaries are not paid
> > * Items of test equipment are likely to be borrowed or people provide
> > access to them for no charge etc,
> > * Academics are likely to provide consultancy for free, in return for
> being
> > on papers published.
> > * Software licenses could probably be obtained free,  or enough people
> get
> > trials.
>
> That’s where the 5:1 cost reduction comes from.
>
> >
> > compared to a commercial company building a maser where
> >
> > * Salaries are paid
> > * All equipment is purchased new
> > * Bench power supplies with 3.5 digit displays are sent out for
> calibration
> > each year.
> > *  No outside body will do anything except at a commercial rate.
> > * Flights are booked for meetings which could be done over the Internet.
> > * High end software licenses are huge.
> >
> >> $500M for the fountain.
> >
> > But on what basis do you arrive at that figure?
>
> The numbers that the people who have done it come up with when you talk to
> them.
>
> >
> >> To get sponsorship for anything remotely close to those numbers, you
> >> need to have some massively good credentials.
> >>
> >> Bob
> >
> > Yes agreed at $500M. But someone like Tom, who does have massively good
> > credentials, could perhaps get $500,000, and perhaps that wisely spent
> > could get a fountain built.  Without knowing how you arrive at $500M, it
> is
> > not possible for anyone to look at ways of shaving that cost.
>
>
> This is *not* a cheap field to be doing things in ….
>
> Bob
>
> >
> > The Lovell Telescope at Jodrell Bank in the UK was built on a shoestring
> > budget. It was at the time the world's  largest steerable radio
> telephone.
> > Half a century later only 2 larger ones have been built.
> >
> > Maybe I am too nieve.
> >
> > Dave.
> > ___
> > 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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> mailman/listinfo/time-nuts
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Re: [time-nuts] hm H Maser

[ewkehren via time-nuts]

Do we know what the PHM development for Galileo cost?




Sent from Samsung tabletBob Camp  wrote:Hi

> On Jan 10, 2017, at 2:45 AM, Dr. David Kirkby (Kirkby Microwave Ltd) 
>  wrote:
> 
> Once 9 Jan 2017 12:59, "Bob Camp"  wrote:
>> 
>> Hi
>> 
>> Ok here are some rough numbers:
>> 
>>> On Jan 9, 2017, at 4:35 AM, Dr. David Kirkby (Kirkby Microwave Ltd) <
> drkir...@kirkbymicrowave.co.uk> wrote:
> 
>>> It would be interesting to see your breakdown of the costs and man hours
>>> for an H2 maser. I suspect that others would find cheaper/faster
> solutions.
>> 
>> $100M for the H2
>> 
>> $25M for the Rb
> 
> With all due respect,  and I apprectiate you have a good knowledge of this
> field, but that's not a breakdown of costs or man hours I wanted to see,
> but a cost which appears to be plucked from the air.

Hardly plucked from the air. The last Rb design that I was involved with was 
roughly 5X that expensive. 

> 
> There's a BIG difference between a volunteer effort where
> 
> * Salaries are not paid
> * Items of test equipment are likely to be borrowed or people provide
> access to them for no charge etc,
> * Academics are likely to provide consultancy for free, in return for being
> on papers published.
> * Software licenses could probably be obtained free,  or enough people get
> trials.

That’s where the 5:1 cost reduction comes from. 

> 
> compared to a commercial company building a maser where
> 
> * Salaries are paid
> * All equipment is purchased new
> * Bench power supplies with 3.5 digit displays are sent out for calibration
> each year.
> *  No outside body will do anything except at a commercial rate.
> * Flights are booked for meetings which could be done over the Internet.
> * High end software licenses are huge.
> 
>> $500M for the fountain.
> 
> But on what basis do you arrive at that figure?

The numbers that the people who have done it come up with when you talk to 
them. 

> 
>> To get sponsorship for anything remotely close to those numbers, you
>> need to have some massively good credentials.
>> 
>> Bob
> 
> Yes agreed at $500M. But someone like Tom, who does have massively good
> credentials, could perhaps get $500,000, and perhaps that wisely spent
> could get a fountain built.  Without knowing how you arrive at $500M, it is
> not possible for anyone to look at ways of shaving that cost.


This is *not* a cheap field to be doing things in ….

Bob

> 
> The Lovell Telescope at Jodrell Bank in the UK was built on a shoestring
> budget. It was at the time the world's  largest steerable radio telephone.
> Half a century later only 2 larger ones have been built.
> 
> Maybe I am too nieve.
> 
> Dave.
> ___
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Re: [time-nuts] hm H Maser

[Bob Camp]

Hi

> On Jan 10, 2017, at 2:45 AM, Dr. David Kirkby (Kirkby Microwave Ltd) 
>  wrote:
> 
> Once 9 Jan 2017 12:59, "Bob Camp"  wrote:
>> 
>> Hi
>> 
>> Ok here are some rough numbers:
>> 
>>> On Jan 9, 2017, at 4:35 AM, Dr. David Kirkby (Kirkby Microwave Ltd) <
> drkir...@kirkbymicrowave.co.uk> wrote:
> 
>>> It would be interesting to see your breakdown of the costs and man hours
>>> for an H2 maser. I suspect that others would find cheaper/faster
> solutions.
>> 
>> $100M for the H2
>> 
>> $25M for the Rb
> 
> With all due respect,  and I apprectiate you have a good knowledge of this
> field, but that's not a breakdown of costs or man hours I wanted to see,
> but a cost which appears to be plucked from the air.

Hardly plucked from the air. The last Rb design that I was involved with was 
roughly 5X that expensive. 

> 
> There's a BIG difference between a volunteer effort where
> 
> * Salaries are not paid
> * Items of test equipment are likely to be borrowed or people provide
> access to them for no charge etc,
> * Academics are likely to provide consultancy for free, in return for being
> on papers published.
> * Software licenses could probably be obtained free,  or enough people get
> trials.

That’s where the 5:1 cost reduction comes from. 

> 
> compared to a commercial company building a maser where
> 
> * Salaries are paid
> * All equipment is purchased new
> * Bench power supplies with 3.5 digit displays are sent out for calibration
> each year.
> *  No outside body will do anything except at a commercial rate.
> * Flights are booked for meetings which could be done over the Internet.
> * High end software licenses are huge.
> 
>> $500M for the fountain.
> 
> But on what basis do you arrive at that figure?

The numbers that the people who have done it come up with when you talk to 
them. 

> 
>> To get sponsorship for anything remotely close to those numbers, you
>> need to have some massively good credentials.
>> 
>> Bob
> 
> Yes agreed at $500M. But someone like Tom, who does have massively good
> credentials, could perhaps get $500,000, and perhaps that wisely spent
> could get a fountain built.  Without knowing how you arrive at $500M, it is
> not possible for anyone to look at ways of shaving that cost.


This is *not* a cheap field to be doing things in ….

Bob

> 
> The Lovell Telescope at Jodrell Bank in the UK was built on a shoestring
> budget. It was at the time the world's  largest steerable radio telephone.
> Half a century later only 2 larger ones have been built.
> 
> Maybe I am too nieve.
> 
> Dave.
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Re: [time-nuts] hm H Maser

[Dr. David Kirkby (Kirkby Microwave Ltd)]

Once 9 Jan 2017 12:59, "Bob Camp"  wrote:
>
> Hi
>
> Ok here are some rough numbers:
>
> > On Jan 9, 2017, at 4:35 AM, Dr. David Kirkby (Kirkby Microwave Ltd) <
drkir...@kirkbymicrowave.co.uk> wrote:

> > It would be interesting to see your breakdown of the costs and man hours
> > for an H2 maser. I suspect that others would find cheaper/faster
solutions.
>
> $100M for the H2
>
> $25M for the Rb

With all due respect,  and I apprectiate you have a good knowledge of this
field, but that's not a breakdown of costs or man hours I wanted to see,
but a cost which appears to be plucked from the air.

There's a BIG difference between a volunteer effort where

* Salaries are not paid
* Items of test equipment are likely to be borrowed or people provide
access to them for no charge etc,
* Academics are likely to provide consultancy for free, in return for being
on papers published.
* Software licenses could probably be obtained free,  or enough people get
trials.

compared to a commercial company building a maser where

* Salaries are paid
* All equipment is purchased new
* Bench power supplies with 3.5 digit displays are sent out for calibration
each year.
*  No outside body will do anything except at a commercial rate.
* Flights are booked for meetings which could be done over the Internet.
* High end software licenses are huge.

> $500M for the fountain.

But on what basis do you arrive at that figure?

> To get sponsorship for anything remotely close to those numbers, you
> need to have some massively good credentials.
>
> Bob

Yes agreed at $500M. But someone like Tom, who does have massively good
credentials, could perhaps get $500,000, and perhaps that wisely spent
could get a fountain built.  Without knowing how you arrive at $500M, it is
not possible for anyone to look at ways of shaving that cost.

The Lovell Telescope at Jodrell Bank in the UK was built on a shoestring
budget. It was at the time the world's  largest steerable radio telephone.
Half a century later only 2 larger ones have been built.

Maybe I am too nieve.

Dave.
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Re: [time-nuts] hm H Maser

[Bob Camp]

Hi 

Ok here are some rough numbers:

> On Jan 9, 2017, at 4:35 AM, Dr. David Kirkby (Kirkby Microwave Ltd) 
>  wrote:
> 
> On 8 Jan 2017 17:34, "Bob Camp"  wrote:
> 
>> You are talking about a project that will take many years and likely
>> more money than the price of a new home. If that is “fun money”, then
>> fine. For most people that sort of commitment is a bit outside the range
>> of do it for fun.
> 
> It would be interesting to see your breakdown of the costs and man hours
> for an H2 maser. I suspect that others would find cheaper/faster solutions.

$100M for the H2

$25M for the Rb

> 
>> Even as a “fun project”, I question the bang for the buck. If cost and
> time
>> are no object, why not do an optical ion standard or a Cesium fountain?
>> I would suggest that both are more cool than than a maser and likely
>> have a lot more fun aspects to them. You then would have something
>> truly unique and not simply a more expensive / poorer performing example
>> of something you could have bought.
> 
> You raise an interesting point.
> 
> I suspect that if a serious attempt was made at a caesium fountain by a
> *group* of people, they might end up with donated parts from places like
> NIST, NPL etc.
> 
> Commercial sponsorship  could conceivability be an option to funding such a
> project, as could wealthy individuals like Richard Branson or James Dyson,
> both of whom are interested in technically challenging projects.
> 
> $100 would not go far, but I personally would be willing to donate $100
> towards the cost of such a project, just to feel part of it.

$500M for the fountain. 

To get sponsorship for anything remotely close to those numbers, you 
need to have some massively good credentials. 

Bob

> 
>> Bob
> 
> Dave
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Re: [time-nuts] hm H Maser

[Bob Camp]

Hi

> On Jan 9, 2017, at 1:05 AM, Bruce Griffiths  
> wrote:
> 
> For a rubidium vpour standard a cavity is essential, one could always use a 
> microwave horn to illuminate the cell in an anechoic chamber.


The cavity in an Rb is not the ultra high Q monster that you have in a Maser. 
There is 
no magic “minimum Q” requirement to get the beast to work. That’s by no means 
saying
that the cavity is unimportant or trivial. The point is only that it’s about 2 
orders of magnitude
easier to make up the required cavity for the Rb.

It should be noted that cavity != shielding and that cavity != temperature 
control. It is simply 
the microwave resonant structure that gets the electromagnetic doing the right 
thing. In both
cases you still need (very) good magnetic shielding, pressure shielding, and 
temperature 
control. In the Rb case, you need to set up specific temperatures to get things 
to work in
each cell. In the Maser case you simply need the “right” temperature for your 
setup. 

Traditionally one of the big deals about both devices was the synthesizer 
required to convert
the physics based frequency to something useful. With the Maser the frequency 
is pretty
much always the same number. That gives a simpler synthesizer in terms of 
tuning. A whole
raft of this and that give you a range of answers for the Rb. That used to make 
the synthesizer
a bit of  a pain to design. These days, the synthesizer tuning the Rb requires 
is easily done with
a cheap DDS chip. Take a look at the 5065 manual if you want to see how much 
fun that
used to be …

Indeed the whole electronics side of both standards is easier than it once was. 
The temperature
probes in the compact Maser still are $1K each, but most of the parts you need 
on the electronics
side are pretty common items. Again, common parts != trivial design. You still 
need to get the
details right. Signal to noise *does* matter. You need to use the right design 
with the right parts. 

So how do you do this? The normal approach is to get a dozen or so people 
together and work 
on it 40 hours a week for about 5 years. You build up a series of batches of 
prototypes and 
get to the point you believe you have a design (1 in 10 sort of works). You 
then spend roughly 
another three to five years knocking the rough edges off of that design and 
making the first 
batch of real units. Beyond time and people there is the cost of parts, 
software licenses, normal
test gear, really weird test gear, and all the other stuff.  This assumes it is 
run as a business with
somebody managing the whole thing. Try to run it as a committee of the whole, 
both the cost
and the time will go up. Try to do it without the right tools, at lest the time 
will go up. I’d bet
the cost will go up as well…

Bob

> Using an integrating sphere can enhance the contrast of the optical signal 
> significantly.
> 
> http://www.princeton.edu/physics/graduate-program/theses/theses-from-2011-1/bmcguyer_dissertation.pdf
> 
> https://infoscience.epfl.ch/record/178228/files/IFCS_Invited_Talk_Finalpdf.pdf
> 
> https://doc.rero.ch/record/32317/files/2318.pdf
> 
> http://tf.nist.gov/general/pdf/1154.pdf
> 
> http://tf.boulder.nist.gov/general/pdf/1663.pdf
> 
> 
> Bruce
> On Sunday, January 08, 2017 10:20:33 PM Bruce Griffiths wrote:
>> Possible sources of Rubium vapour
>> 
> cells:https://www.thorlabs.com/newgrouppage9.cfm?objectgroup_id=1470
>> 
>> http://www.precisionglassblowing.com/custom-solutions/optical-glassware/vapo
>> r-wavelength-reference-cells/
>> 
>> https://www.sacher-laser.com/home/lab-equipment/spectroscopy/reference_gas_a
>> nd_vapor_cells/reference_gas_and_vapor_cells.html
>> 
>> 
>> Bruce
>> 
>>On Monday, 9 January 2017 11:14 AM, Bruce Griffiths
>>  wrote:
>> 
>> 
>> Bob
>> As long as one stays away from CPT and merely uses the laser as a
>> replacement for the traditional rubidium lamp plus filters it should be
>> easy enough as one doesnt need to modulate the laser at 3.4 GHz.I was
>> thinking something along the lines of the recent PhD thesis that gave all
>> the detail required to duplicate their low noise rubidium standard that 
> was
>> quieter than am HP5065.One could easily substitute ones own ECDL 
> (These can
>> easily be constructed from commercially available parts) and improve
>> somewhat on the performance (The oven design of most commercial 
> ECDLs seems
>> suboptimal). Bruce
>> 
>>On Monday, 9 January 2017 10:23 AM, Bob Camp  
> wrote:
>> 
>> 
>> Hi
>> 
>> The large diameter Rb cells are a bit harder to come by than the more
>> generic telecom sized cells. I suspect you are correct and they are out
>> there from somebody.. The real advantage you would have with an Rb is 
> that
>> the design you do is gigantic compared to what everybody is doing 
> today.
>> Their constraints are not your constraints.
>> 
>> Based on the laser driven Rb on my bench …. don’t bother with that part 
> 

Re: [time-nuts] hm H Maser

[timeok]

   Bob, Dave,
The most big problem is to find a group of relatively close people with the 
will to spend many hours, months for this project.
Here in Italy I found some people who work in public university who are 
available to give external help, for example they were
given a Pirani sensor and they are available to provide a turbo-molecular pump.
I've found who I could also realize the resonant cavity and the necessary 
mechanical parts but not the team..
The main problem is to find three or four helpful people who have the courage 
to start this adventure.
Luciano
www.timeok.it


   From "time-nuts" time-nuts-boun...@febo.com
   To "Discussion of precise time and frequency measurement" time-nuts@febo.com
   Cc
   Date Mon, 9 Jan 2017 09:35:32 +0000
   Subject Re: [time-nuts] hm H Maser
   On 8 Jan 2017 17:34, "Bob Camp" <kb...@n1k.org> wrote:

   > You are talking about a project that will take many years and likely
   > more money than the price of a new home. If that is “fun money”, then
   > fine. For most people that sort of commitment is a bit outside the range
   > of do it for fun.

   It would be interesting to see your breakdown of the costs and man hours
   for an H2 maser. I suspect that others would find cheaper/faster solutions.

   > Even as a “fun project”, I question the bang for the buck. If cost and
   time
   > are no object, why not do an optical ion standard or a Cesium fountain?
   > I would suggest that both are more cool than than a maser and likely
   > have a lot more fun aspects to them. You then would have something
   > truly unique and not simply a more expensive / poorer performing example
   > of something you could have bought.

   You raise an interesting point.

   I suspect that if a serious attempt was made at a caesium fountain by a
   *group* of people, they might end up with donated parts from places like
   NIST, NPL etc.

   Commercial sponsorship could conceivability be an option to funding such a
   project, as could wealthy individuals like Richard Branson or James Dyson,
   both of whom are interested in technically challenging projects.

   $100 would not go far, but I personally would be willing to donate $100
   towards the cost of such a project, just to feel part of it.

   > Bob

   Dave
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Re: [time-nuts] hm H Maser

[Dr. David Kirkby (Kirkby Microwave Ltd)]

On 8 Jan 2017 17:34, "Bob Camp"  wrote:

> You are talking about a project that will take many years and likely
> more money than the price of a new home. If that is “fun money”, then
> fine. For most people that sort of commitment is a bit outside the range
> of do it for fun.

It would be interesting to see your breakdown of the costs and man hours
for an H2 maser. I suspect that others would find cheaper/faster solutions.

> Even as a “fun project”, I question the bang for the buck. If cost and
time
> are no object, why not do an optical ion standard or a Cesium fountain?
> I would suggest that both are more cool than than a maser and likely
> have a lot more fun aspects to them. You then would have something
> truly unique and not simply a more expensive / poorer performing example
> of something you could have bought.

You raise an interesting point.

I suspect that if a serious attempt was made at a caesium fountain by a
*group* of people, they might end up with donated parts from places like
NIST, NPL etc.

Commercial sponsorship  could conceivability be an option to funding such a
project, as could wealthy individuals like Richard Branson or James Dyson,
both of whom are interested in technically challenging projects.

$100 would not go far, but I personally would be willing to donate $100
towards the cost of such a project, just to feel part of it.

> Bob

Dave
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Re: [time-nuts] hm H Maser

[Bruce Griffiths]

For a rubidium vpour standard a cavity is essential, one could always use a 
microwave horn to illuminate the cell in an anechoic chamber.
Using an integrating sphere can enhance the contrast of the optical signal 
significantly.

http://www.princeton.edu/physics/graduate-program/theses/theses-from-2011-1/bmcguyer_dissertation.pdf

https://infoscience.epfl.ch/record/178228/files/IFCS_Invited_Talk_Finalpdf.pdf

https://doc.rero.ch/record/32317/files/2318.pdf

http://tf.nist.gov/general/pdf/1154.pdf

http://tf.boulder.nist.gov/general/pdf/1663.pdf


Bruce
On Sunday, January 08, 2017 10:20:33 PM Bruce Griffiths wrote:
> Possible sources of Rubium vapour
> 
cells:https://www.thorlabs.com/newgrouppage9.cfm?objectgroup_id=1470
> 
> http://www.precisionglassblowing.com/custom-solutions/optical-glassware/vapo
> r-wavelength-reference-cells/
> 
> https://www.sacher-laser.com/home/lab-equipment/spectroscopy/reference_gas_a
> nd_vapor_cells/reference_gas_and_vapor_cells.html
> 
> 
> Bruce
> 
> On Monday, 9 January 2017 11:14 AM, Bruce Griffiths
>  wrote:
> 
> 
>  Bob
> As long as one stays away from CPT and merely uses the laser as a
> replacement for the traditional rubidium lamp plus filters it should be
> easy enough as one doesnt need to modulate the laser at 3.4 GHz.I was
> thinking something along the lines of the recent PhD thesis that gave all
> the detail required to duplicate their low noise rubidium standard that 
was
> quieter than am HP5065.One could easily substitute ones own ECDL 
(These can
> easily be constructed from commercially available parts) and improve
> somewhat on the performance (The oven design of most commercial 
ECDLs seems
> suboptimal). Bruce
> 
> On Monday, 9 January 2017 10:23 AM, Bob Camp  
wrote:
> 
> 
>  Hi
> 
> The large diameter Rb cells are a bit harder to come by than the more
> generic telecom sized cells. I suspect you are correct and they are out
> there from somebody.. The real advantage you would have with an Rb is 
that
> the design you do is gigantic compared to what everybody is doing 
today.
> Their constraints are not your constraints.
> 
> Based on the laser driven Rb on my bench …. don’t bother with that part 
of
> it. It is indeed doable. Doing it in a fashion that gives you a better
> standard …. not really easy at all.
> 
> Bob
> 
> > On Jan 8, 2017, at 3:55 PM, Bruce Griffiths 

> > wrote:
> > 
> > The rubidium standard appears much more manageable given that 
the cavity
> > dimensions are somewhat more compact and rubidium vapour cells 
are
> > readily available. Substituting a laser for the lamp should also help in
> > improving the reliability. However an ECDL laser locked to a rubidium
> > line is required for a double resonance setup. Building ones own ECDL
> > doesn't appear to be particularly daunting, however low noise drive
> > electronics will be required. All the necessary optics are off the shelf
> > items. One still has the issue of  the frequency pulling due to the
> > presence of the vapour cell. Bruce
> > 
> > On Sunday, January 08, 2017 10:22:54 AM you wrote:
> > > Hi
> > > 
> > > I guess the question then would be:
> > > 
> > > Is a H Maser that runs 6.6 x 10^-12 at 1 second worth the trouble?
> > > 
> > > With 100 KHz / C temperature coefficients running around, getting
> > > good stability in a real world setting at 1 day will be “interesting”.
> > > 
> > > Just for reference:  The MH-2010 data sheet shows 1.5x10^-13 at
> > > 1 second for the “cheap” version and 8x10^-14 at one second for
> > > the low noise version.  Data showing the 5065 Rb at 1x10^-12 at
> > > 1 second is running around on various web sites.
> > > 
> > > The NIST paper suggests that they made several prototypes before
> > > they got one good one working. That’s a lot of “fun and games” with
> > > ceramic machine lathes and Rb magnetometers…..
> > > 
> > > The punch line being - would the same effort / cost / many years of 
time
> > > be
> > > more fruitful (ADEV wise) doing a large package Rb (like a 5065) ? 
> > > Based
> > > on the number of people making them in volume over the years, 
Rb’s
> > > appear
> > > to be the easier item to debug, design, and build.
> > > 
> > > Bob
> > > 
> > > > On Jan 8, 2017, at 6:01 AM, Bruce Griffiths
> > > > 
> > > > wrote:
> > > > 
> > > > You could try a cavity like the one
> > > > in;http://tf.nist.gov/general/pdf/156.pdf
> > > > 
> > > > This avoids the requirement for a fused quartz storage bulb.
> > > > Bruce
> > > >
> > > >On Sunday, 8 January 2017 11:33 PM, timeok 
 wrote:
> > > > Hi,
> > > > the thought of being able to work on building a H Maser has 
always
> > > > accompanied me in recent years. I fully understand the many
> > > > difficulties
> > > > of this project and also the necessity of a work team. Maybe a 
Passive
> > > > Maser would be easiest to implement, but I do not know in detail 

Re: [time-nuts] hm H Maser

[Bruce Griffiths]

Bob
As long as one stays away from CPT and merely uses the laser as a replacement 
for the traditional rubidium lamp plus filters it should be easy enough as one 
doesnt need to modulate the laser at 3.4 GHz.I was thinking something along the 
lines of the recent PhD thesis that gave all the detail required to duplicate 
their low noise rubidium standard that was quieter than am HP5065.One could 
easily substitute ones own ECDL (These can easily be constructed from 
commercially available parts) and improve somewhat on the performance (The oven 
design of most commercial ECDLs seems suboptimal).
Bruce 

On Monday, 9 January 2017 10:23 AM, Bob Camp  wrote:
 

 Hi

The large diameter Rb cells are a bit harder to come by than the more generic 
telecom 
sized cells. I suspect you are correct and they are out there from somebody.. 
The real 
advantage you would have with an Rb is that the design you do is gigantic 
compared to
what everybody is doing today. Their constraints are not your constraints. 

Based on the laser driven Rb on my bench …. don’t bother with that part of it. 
It is indeed
doable. Doing it in a fashion that gives you a better standard …. not really 
easy at all.

Bob


> On Jan 8, 2017, at 3:55 PM, Bruce Griffiths  
> wrote:
> 
> The rubidium standard appears much more manageable given that the cavity 
> dimensions are somewhat more compact and rubidium vapour cells are readily 
> available. Substituting a laser for the lamp should also help in improving 
> the reliability. However an ECDL laser locked to a rubidium line is required 
> for a double resonance setup. Building ones own ECDL doesn't appear to be 
> particularly daunting, however low noise drive electronics will be required. 
> All the necessary optics are off the shelf items.
> One still has the issue of  the frequency pulling due to the presence of the 
> vapour cell.
> Bruce
> On Sunday, January 08, 2017 10:22:54 AM you wrote:
> > Hi
> > 
> > I guess the question then would be:
> > 
> > Is a H Maser that runs 6.6 x 10^-12 at 1 second worth the trouble?
> > 
> > With 100 KHz / C temperature coefficients running around, getting
> > good stability in a real world setting at 1 day will be “interesting”.
> > 
> > Just for reference:  The MH-2010 data sheet shows 1.5x10^-13 at
> > 1 second for the “cheap” version and 8x10^-14 at one second for
> > the low noise version.  Data showing the 5065 Rb at 1x10^-12 at
> > 1 second is running around on various web sites.
> > 
> > The NIST paper suggests that they made several prototypes before
> > they got one good one working. That’s a lot of “fun and games” with
> > ceramic machine lathes and Rb magnetometers…..
> > 
> > The punch line being - would the same effort / cost / many years of time be
> > more fruitful (ADEV wise) doing a large package Rb (like a 5065) ?  Based
> > on the number of people making them in volume over the years, Rb’s appear
> > to be the easier item to debug, design, and build.
> > 
> > Bob
> > 
> > > On Jan 8, 2017, at 6:01 AM, Bruce Griffiths 
> > > wrote:
> > > 
> > > You could try a cavity like the one
> > > in;http://tf.nist.gov/general/pdf/156.pdf
> > > 
> > > This avoids the requirement for a fused quartz storage bulb.
> > > Bruce
> > > 
> > >    On Sunday, 8 January 2017 11:33 PM, timeok  wrote:
> > > Hi,
> > > the thought of being able to work on building a H Maser has always
> > > accompanied me in recent years. I fully understand the many difficulties
> > > of this project and also the necessity of a work team. Maybe a Passive
> > > Maser would be easiest to implement, but I do not know in detail the
> > > processes of construction of the physical part of the interrogation.
> > > Honestly, I would love to spend My next ten years on a project like this,
> > > but... my curiosity is to know of there are other people with these
> > > mental disorders on earth.
> > > 
> > > If you want to answer me.
> > > Luciano
> > > www.timeok.it
> > > ___


   
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Re: [time-nuts] hm H Maser

[Bob Camp]

Hi

> On Jan 8, 2017, at 11:57 AM, William H. Fite  wrote:
> 
> Bob, I think you're missing the point here. This is not the quest for
> utimate standards of accuracy/precision/resolution, it Is not about
> economic viability, or even attainability, let alone being "worth the
> trouble.".
> 
> It is about a fun project. Fun even if it comes to nothing. Is that
> difficult to understand?

You are talking about a project that will take many years and likely 
more money than the price of a new home. If that is “fun money”, then
fine. For most people that sort of commitment is a bit outside the range
of do it for fun. 

Even as a “fun project”, I question the bang for the buck. If cost and time
are no object, why not do an optical ion standard or a Cesium fountain?
I would suggest that both are more cool than than a maser and likely 
have a lot more fun aspects to them. You then would have something 
truly unique and not simply a more expensive / poorer performing example
of something you could have bought. 

Having been down this road before, there is a *lot* of physics involved
in any of these standards. You may not quite do the work to earn ( possibly 
another) Phd in Physics, but if you do it alone, the learning will be close. 

I’m by no means saying don’t do it. That is very much up to the individual
to decide. What I’m saying is that to have any chance of completing the 
project, you need to face up to the costs (both money and time) up front. 
If you don’t, this will simply become an exercise in thrashing around. 

Bob


> 
> 
> 

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Re: [time-nuts] hm H Maser

[William H. Fite]

Bob, I think you're missing the point here. This is not the quest for
utimate standards of accuracy/precision/resolution, it Is not about
economic viability, or even attainability, let alone being "worth the
trouble.".

It is about a fun project. Fun even if it comes to nothing. Is that
difficult to understand?



On Sunday, January 8, 2017, Bob Camp  wrote:

> Hi
>
> > On Jan 8, 2017, at 11:21 AM, Dr. David Kirkby (Kirkby Microwave Ltd) <
> drkir...@kirkbymicrowave.co.uk > wrote:
> >
> > On 8 January 2017 at 15:22, Bob Camp >
> wrote:
> >
> >> Hi
> >>
> >> I guess the question then would be:
> >>
> >> Is a H Maser that runs 6.6 x 10^-12 at 1 second worth the trouble?
> >>
> >> With 100 KHz / C temperature coefficients running around, getting
> >> good stability in a real world setting at 1 day will be “interesting”.
> >>
> >> Just for reference:  The MH-2010 data sheet shows 1.5x10^-13 at
> >> 1 second for the “cheap” version and 8x10^-14 at one second for
> >> the low noise version.  Data showing the 5065 Rb at 1x10^-12 at
> >> 1 second is running around on various web sites.
> >>
> >> The NIST paper suggests that they made several prototypes before
> >> they got one good one working. That’s a lot of “fun and games” with
> >> ceramic machine lathes and Rb magnetometers…..
> >>
> >> The punch line being - would the same effort / cost / many years of time
> >> be more
> >> fruitful (ADEV wise) doing a large package Rb (like a 5065) ?  Based on
> >> the number of people making them in volume over the years, Rb’s appear
> to
> >> be the easier item to debug, design, and build.
> >>
> >> Bob
> >>
> >
> > If you build a H2 maser, you would learn a lot more than building a bunch
> > of rubidiums. That sounds a good enough reason to me.
>
>
> I’m not sure I agree with that. Both have their own issues. Much of the
> learning
> in both cases involves fiddly mechanical and machining details. Working
> each
> out by a lot of trial and error would be useful for that particular
> standard. It’s hard
> to see how it would be useful for much else …. Yes, there is a bunch of
> obscure
> physics involved in each, but again it’s very use specific stuff.
>
> Bob
>
> >
> > I've been contemplating buying one of the older HP 5061A or 5061B cesium
> > frequency standards from eBay. Almost all are sold as "for spares or
> > repair", and are probably not going to be economically viable to get
> > working due to the fact the tubes are probably useless. But I'd sure
> learn
> > a lot from playing around inside one of the older ones.
> >
> > Dave
> > ___
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> > To unsubscribe, go to https://www.febo.com/cgi-bin/
> mailman/listinfo/time-nuts
> > and follow the instructions there.
>
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>


-- 
If you gaze long into an abyss, your coffee will get cold.
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Re: [time-nuts] hm H Maser

[Bob Camp]

Hi

> On Jan 8, 2017, at 11:21 AM, Dr. David Kirkby (Kirkby Microwave Ltd) 
>  wrote:
> 
> On 8 January 2017 at 15:22, Bob Camp  wrote:
> 
>> Hi
>> 
>> I guess the question then would be:
>> 
>> Is a H Maser that runs 6.6 x 10^-12 at 1 second worth the trouble?
>> 
>> With 100 KHz / C temperature coefficients running around, getting
>> good stability in a real world setting at 1 day will be “interesting”.
>> 
>> Just for reference:  The MH-2010 data sheet shows 1.5x10^-13 at
>> 1 second for the “cheap” version and 8x10^-14 at one second for
>> the low noise version.  Data showing the 5065 Rb at 1x10^-12 at
>> 1 second is running around on various web sites.
>> 
>> The NIST paper suggests that they made several prototypes before
>> they got one good one working. That’s a lot of “fun and games” with
>> ceramic machine lathes and Rb magnetometers…..
>> 
>> The punch line being - would the same effort / cost / many years of time
>> be more
>> fruitful (ADEV wise) doing a large package Rb (like a 5065) ?  Based on
>> the number of people making them in volume over the years, Rb’s appear to
>> be the easier item to debug, design, and build.
>> 
>> Bob
>> 
> 
> If you build a H2 maser, you would learn a lot more than building a bunch
> of rubidiums. That sounds a good enough reason to me.


I’m not sure I agree with that. Both have their own issues. Much of the learning
in both cases involves fiddly mechanical and machining details. Working each
out by a lot of trial and error would be useful for that particular standard. 
It’s hard
to see how it would be useful for much else …. Yes, there is a bunch of obscure
physics involved in each, but again it’s very use specific stuff. 

Bob

> 
> I've been contemplating buying one of the older HP 5061A or 5061B cesium
> frequency standards from eBay. Almost all are sold as "for spares or
> repair", and are probably not going to be economically viable to get
> working due to the fact the tubes are probably useless. But I'd sure learn
> a lot from playing around inside one of the older ones.
> 
> Dave
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Re: [time-nuts] hm H Maser

[Dr. David Kirkby (Kirkby Microwave Ltd)]

On 8 January 2017 at 15:22, Bob Camp  wrote:

> Hi
>
> I guess the question then would be:
>
> Is a H Maser that runs 6.6 x 10^-12 at 1 second worth the trouble?
>
> With 100 KHz / C temperature coefficients running around, getting
> good stability in a real world setting at 1 day will be “interesting”.
>
> Just for reference:  The MH-2010 data sheet shows 1.5x10^-13 at
> 1 second for the “cheap” version and 8x10^-14 at one second for
> the low noise version.  Data showing the 5065 Rb at 1x10^-12 at
> 1 second is running around on various web sites.
>
> The NIST paper suggests that they made several prototypes before
> they got one good one working. That’s a lot of “fun and games” with
> ceramic machine lathes and Rb magnetometers…..
>
> The punch line being - would the same effort / cost / many years of time
> be more
> fruitful (ADEV wise) doing a large package Rb (like a 5065) ?  Based on
> the number of people making them in volume over the years, Rb’s appear to
> be the easier item to debug, design, and build.
>
> Bob
>

If you build a H2 maser, you would learn a lot more than building a bunch
of rubidiums. That sounds a good enough reason to me.

I've been contemplating buying one of the older HP 5061A or 5061B cesium
frequency standards from eBay. Almost all are sold as "for spares or
repair", and are probably not going to be economically viable to get
working due to the fact the tubes are probably useless. But I'd sure learn
a lot from playing around inside one of the older ones.

Dave
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Re: [time-nuts] hm H Maser

[Bob Camp]

Hi

I guess the question then would be: 

Is a H Maser that runs 6.6 x 10^-12 at 1 second worth the trouble? 

With 100 KHz / C temperature coefficients running around, getting 
good stability in a real world setting at 1 day will be “interesting”. 

Just for reference:  The MH-2010 data sheet shows 1.5x10^-13 at 
1 second for the “cheap” version and 8x10^-14 at one second for
the low noise version.  Data showing the 5065 Rb at 1x10^-12 at
1 second is running around on various web sites. 

The NIST paper suggests that they made several prototypes before
they got one good one working. That’s a lot of “fun and games” with
ceramic machine lathes and Rb magnetometers…..

The punch line being - would the same effort / cost / many years of time be more
fruitful (ADEV wise) doing a large package Rb (like a 5065) ?  Based on
the number of people making them in volume over the years, Rb’s appear to 
be the easier item to debug, design, and build. 

Bob


> On Jan 8, 2017, at 6:01 AM, Bruce Griffiths  
> wrote:
> 
> You could try a cavity like the one in;http://tf.nist.gov/general/pdf/156.pdf
> 
> This avoids the requirement for a fused quartz storage bulb.
> Bruce 
> 
>On Sunday, 8 January 2017 11:33 PM, timeok  wrote:
> 
> 
> 
> Hi,
> the thought of being able to work on building a H Maser has always 
> accompanied me in recent years.
> I fully understand the many difficulties of this project and also the 
> necessity of a work team.
> Maybe a Passive Maser would be easiest to implement, but I do not know in 
> detail the processes
> of construction of the physical part of the interrogation.
> Honestly, I would love to spend My next ten years on a project like this, 
> but...
> my curiosity is to know of there are other people with these mental disorders 
> on earth.
> 
> If you want to answer me.
> Luciano
> www.timeok.it
> ___
> 

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Re: [time-nuts] hm H Maser

[Bruce Griffiths]

You could try a cavity like the one in;http://tf.nist.gov/general/pdf/156.pdf

This avoids the requirement for a fused quartz storage bulb.
Bruce 

On Sunday, 8 January 2017 11:33 PM, timeok  wrote:
 

 
Hi,
the thought of being able to work on building a H Maser has always accompanied 
me in recent years.
I fully understand the many difficulties of this project and also the necessity 
of a work team.
Maybe a Passive Maser would be easiest to implement, but I do not know in 
detail the processes
of construction of the physical part of the interrogation.
Honestly, I would love to spend My next ten years on a project like this, but...
my curiosity is to know of there are other people with these mental disorders 
on earth.

If you want to answer me.
Luciano
www.timeok.it
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[time-nuts] hm H Maser

[timeok]

Hi,
the thought of being able to work on building a H Maser has always accompanied 
me in recent years.
I fully understand the many difficulties of this project and also the necessity 
of a work team.
Maybe a Passive Maser would be easiest to implement, but I do not know in 
detail the processes
of construction of the physical part of the interrogation.
Honestly, I would love to spend My next ten years on a project like this, but...
my curiosity is to know of there are other people with these mental disorders 
on earth.

If you want to answer me.
Luciano
www.timeok.it
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