Re: [time-nuts] hm H Maser
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 kb8tq@n1k.org wrote:
Hi
On Jan 10, 2017, at 5:26 PM, Bob Stewart bob@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) <
To: Discussion of precise time and frequency measurement <
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 <opronningen@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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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
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 paulswedb@gmail.com 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
On Wed, Jan 11, 2017 at 12:25 AM, Bob kb8tq kb8tq@n1k.org 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.
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 gmaxwell@gmail.com wrote:
On Wed, Jan 11, 2017 at 12:25 AM, Bob kb8tq kb8tq@n1k.org 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.
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.
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 <kb8tq@n1k.org> 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 gmaxwell@gmail.com wrote:
On Wed, Jan 11, 2017 at 12:25 AM, Bob kb8tq kb8tq@n1k.org 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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To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
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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 bruce.griffiths@xtra.co.nz 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 <kb8tq@n1k.org> wrote:
Hi
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) <
drkirkby@kirkbymicrowave.co.uk> wrote:
On 10 January 2017 at 15:35, Ole Petter Rønningen opronningen@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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and follow the instructions there.
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 <opronningen@gmail.com> 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) <
drkirkby@kirkbymicrowave.co.uk> wrote:
On 10 January 2017 at 15:35, Ole Petter Rønningen <opronningen@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
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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
phk@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.