Cs tube pics
Hello Nuts,
Yes, I originally had the wrong dash in the link names and did fix it
almost immediately. That is why they now work. (Should have put pictures
with both names in the folder so they would have worked for all)
Tom, really like your third link that has the cover over the microwave
innards cut away. I will have to do that, that way the cover won't be
missing but you can see the copper cavity and C-field coil.
Thanks for the other good links as well. Your pictures at HP are archived
in Google somewhere, as I ran across at least one in my preliminary
research.
Regards,
Skip Withrow
Thanks for the other good links as well. Your pictures at HP are archived
in Google somewhere, as I ran across at least one in my preliminary
research.
Hi Skip,
Ah, now I know what you mean. Around 2005 I took a set of cesium beam tube photos within the semi-public viewing area at hp/Agilent, Santa Clara. These are mostly similar to yours, with some additional tear down of the tube to expose pieces on the ends and middle. The link is here:
http://www.leapsecond.com/pages/cesium-tube/
So if you keep hacking on your tube(s) you should get to the same point as they did. If nothing else, you can use my photos of hp's display as a hint of where and where not to cut! Note that the shinny copper will look fantastic at first but may dull over time. The chemists on the list can recommend how to preserve it.
When you're all done you'll realize just how amazing it is that an entire atomic physics laboratory can be reduced to the size of a 2L water bottle, with a 68000 CPU playing the role of the grad student. It can run 24x7 for 10 to 20 years and remain accurate to better than 1e-13. That's why everyone should own a cesium standard after they grow tired of playing with GPSDO.
/tvb
On Mon, 31 Oct 2016 22:18:07 -0700
"Tom Van Baak" tvb@LeapSecond.com wrote:
That's why everyone should own a cesium standard after they grow tired of playing with GPSDO.
I really would like to do that. But they are a tad bit expensive.
Especially on this side of the big pond. If anyone is willing
to part with a Cs standard and want to have it a good home, feel
free to contact me :-)
Attila Kinali
--
It is upon moral qualities that a society is ultimately founded. All
the prosperity and technological sophistication in the world is of no
use without that foundation.
-- Miss Matheson, The Diamond Age, Neil Stephenson
On 10/31/2016 10:18 PM, Tom Van Baak wrote:
So if you keep hacking on your tube(s) you should get to the same point as they did. If nothing else, you can use my photos of hp's display as a hint of where and where not to cut! Note that the shinny copper will look fantastic at first but may dull over time. The chemists on the list can recommend how to preserve it.
When you're all done you'll realize just how amazing it is that an entire atomic physics laboratory can be reduced to the size of a 2L water bottle, with a 68000 CPU playing the role of the grad student. It can run 24x7 for 10 to 20 years and remain accurate to better than 1e-13. That's why everyone should own a cesium standard after they grow tired of playing with GPSDO.
/tvb
Thanks for posting that Tom. You make me feel
like I'm still relevant :-)
Rick
While I've no need for such accuracy in my little home workshop, I
really would like a Cs standard, just because.
The Rb and GPSDO are more than adequate for my needs but I can understand
(and, for now, manage to resist) the addiction to accuracy and find it
fascinating that such results can be achieved.
On 1 Nov 2016 10:39, "Attila Kinali" attila@kinali.ch wrote:
On Mon, 31 Oct 2016 22:18:07 -0700
"Tom Van Baak" tvb@LeapSecond.com wrote:
That's why everyone should own a cesium standard after they grow tired
of playing with GPSDO.
I really would like to do that. But they are a tad bit expensive.
Especially on this side of the big pond. If anyone is willing
to part with a Cs standard and want to have it a good home, feel
free to contact me :-)
Attila Kinali
--
It is upon moral qualities that a society is ultimately founded. All
the prosperity and technological sophistication in the world is of no
use without that foundation.
-- Miss Matheson, The Diamond Age, Neil Stephenson
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/
mailman/listinfo/time-nuts
and follow the instructions there.
On 10/31/16 10:18 PM, Tom Van Baak wrote:
When you're all done you'll realize just how amazing it is that an entire atomic physics laboratory can be reduced to the size of a 2L water bottle, with a 68000 CPU playing the role of the grad student. It can run 24x7 for 10 to 20 years and remain accurate to better than 1e-13. That's why everyone should own a cesium standard after they grow tired of playing with GPSDO.
Indeed.. we've got two projects at JPL that are in this bucket: one is
the Deep Space Atomic Clock - a trapped mercury ion device; the other is
Cold Atom Lab - which creates Bose Einstein Condensates
Both are basically "take a lab bench full of gear and make it a box
where you can push a switch and have it go ping"
(in space, where almost nobody makes service calls)
There's a whole lot of "undocumented" (or just plainly poorly
understood) idiosyncratic behavior in these sorts of things.
/tvb
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.
Clint:
While I've no need for such accuracy in my little home workshop, I
really would like a Cs standard, just because.
The Rb and GPSDO are more than adequate for my needs but I can understand
(and, for now, manage to resist) the addiction to accuracy and find it
fascinating that such results can be achieved.
Attila:
I really would like to do that. But they are a tad bit expensive.
Especially on this side of the big pond. If anyone is willing
to part with a Cs standard and want to have it a good home, feel
free to contact me :-)
It's true that a cheap GPS receiver is more accurate long-term than a surplus cesium standard, but you're right about the "just because" part. To me at least, this time nut hobby is not so much about the pursuit of accuracy as it is an appreciation for the variety, ingenuity and complexity of timekeeping. In some cases "how it works" is far more interesting that "does it work".
A used but known working cesium standard can be expensive, but like most of you almost all my gear comes from eBay via automated daily keyword searches. Many of my mil- or telecom-surplus FTS 4050 and HP 5061 were obtained for just a couple hundred dollars. You may search for months or even years, but amazing bargains show up. Not all of them work, of course, but the op/svc manuals are superb, the design / construction is very repair-friendly, and there's a weird group called time nuts with helpful advice.
Plus once you get more than one unit you can mix parts and create your own Frankenstein. It turns out that many surplus cesium standards are not dead due to tube failures so its a very happy day when a beat up 5061 turns out to have only a failed power supply or a bad OCXO yet the tube is in perfect condition. I remember one person picked up a "dead" FTS cesium standard only to find the reason it didn't work is that the switch on the back was in standby mode! Only one time nut I know ever bought a replacement Cs tube new from the factory. All the rest of us sift through the graveyard looking for the one that cries "I'm not dead yet".
/tvb
In message CAN7ULzQS4bVwTPsp0kPrd8mNyash4pn7Qgf3zODA9puqnHV++Q@mail.gmail.com, Clint Jay wr
ites:
While I've no need for such accuracy in my little home workshop, I
really would like a Cs standard, just because.
The Rb and GPSDO are more than adequate for my needs but I can understand
(and, for now, manage to resist) the addiction to accuracy and find it
fascinating that such results can be achieved.
Many years a go, we installed ethernet over the entire campus of Denmarks
largest engineering company (FLS). At the center of it all, we had the
first Cisco AGS+ sold, fitted with all ethernet ports.
Of course at some point the CEO comes round and wants to see "that new
expensive network box" which had cost so much money.
I will never forget the look on his face when the CIO opened the rackdoor
and showed him a 6U box with a huge Cisco logo and nothing else.
(https://cdn-images-1.medium.com/max/800/1*A1Qt9uU3lRmzfx_5O_QkgA.png)
Cesiums are a lot like that.
--
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.
On Tue, 1 Nov 2016 09:10:25 -0700
"Tom Van Baak" tvb@LeapSecond.com wrote:
I really would like to do that. But they are a tad bit expensive.
Especially on this side of the big pond. If anyone is willing
to part with a Cs standard and want to have it a good home, feel
free to contact me :-)
It's true that a cheap GPS receiver is more accurate long-term than
a surplus cesium standard, but you're right about the "just because" part.
To me at least, this time nut hobby is not so much about the pursuit of
accuracy as it is an appreciation for the variety, ingenuity and complexity
of timekeeping. In some cases "how it works" is far more interesting that
"does it work".
I think, most of us are in it for the "how it works" and
"how far can I push it". :-)
A used but known working cesium standard can be expensive, but like most of
you almost all my gear comes from eBay via automated daily keyword searches.
Many of my mil- or telecom-surplus FTS 4050 and HP 5061 were obtained for
just a couple hundred dollars. You may search for months or even years, but
amazing bargains show up. Not all of them work, of course, but the op/svc
manuals are superb, the design / construction is very repair-friendly, and
there's a weird group called time nuts with helpful advice.
It still is prohibitevly expensive in Europe. There are much fewer
Cs standards going around than in the US in the first place, and there
is also less a tinkering mentality. Ie a lot of companies just say
"it's broken, it's no use for anyone anymore, let's just scrap it" and
thus a lot of stuff ends up in recycling instead of on ebay. Heck, a couple
of years ago i got an 3458 because the company wanted to throw it away.
Mind you, it was in full working condition, only the NVRAM batteries were low.
I still would like to try to build my own atomic clock at some point,
even if it would be a quite costly, and a many years project.
IMHO the easiest to build would be an Rb or Cs vapor cell using either
dual resonance or coherent population trapping. Cells can be bought
for 300-500€. For a bit more you can get them made to spec. Machining
a resonant cavity from aluminium is pretty easy and cheap these days,
if one wants to go for the dual resonance. The biggest issue for both
types would be the laser system. Either getting the laser diodes selected
(makes them expensive) or build an external cavity for them (creates
the need of a complex control system and not so simple mechanically).
Putting all toghether would probably cost something in the order of
1000€ to 5000€.
One up in difficulty would be a passive hydrogen maser. This requires a
vacuum system and things like platinum leaks to generate atomar hydrogen
and state selection magnets. If one knows glass blowing, part of it can
be made using pyrex tubes, which simplifies some stuff (like keeping the
state selection magnets outside the vacuum system). Also, the cavity
needed would be quite big. A normaly used TE011 cavity is huge. One can
load it with aluminia and get it down to 15-20cm diameter, but this requires
crystaline aluminia to maintain low loss. Maybe one could use other resonating
structures that are smaller, TE111 or loop-gap resonators have been proposed.
The biggest cost here is definitely the needed vacuum system. Although
the rough pumps are rather cheap (around 500-1000€ if one does not need
fast pumping) and some of these actually end up on ebay without being
destryoed by "testing", the high vacuum pumps (ion pumps, turbo pumps etc)
are not cheap and need to bought new (the stuff you see on ebay are either
systems that were removed from labs because they don't work anymore, or
were destroyed by "testing" them in free air).
An active hydrogen maser should not be that much more difficult. It mostly
involves a low loss, correctly tuned cavity and low noise detection electronics.
The input stream of hydrogen atoms needs to be more precisely controlled as
well...
Another step up in difficulty would be a system using a magneto optical trap.
Glass cavities with flanges for vacuum system are readily available and
also cheap. Again, the vacuum system is one difficulty, though probably
simpler than for the hydrogen maser (less parts that need to be custom made).
But the requirements for the vacuum are a bit higher. The laser system poses
a similar difficult as with the CPT system above, but now there are more
lasers and all need to be locked to eachother. The traping laser also need
to be directed at the cavity from 6 sides, all meeting in the center of the
cavity, which makes alignment problematic. This is also the first system
that offers to be a primary standard, although it probably does not get to
the stability of a 5071, as the trapping lasers will induce a light shift
that is not so easy to control unless one goes for the expensive laboratory
grade lasers.
Next on the list would be an Hg ion trap. But there are so many parts
in such a system that are not easily bought and require a very good
understanding of the physics involved to design custom parts, that
it becomes almost unrealistic that an amateur could be build one at home.
Same goes for ion and neutral atom optical clocks. Yes, they can be build,
yes the principle is simple, but getting it actually to work needs a lot
of understanding and tinkering.
Ah... I'm dreaming again :-)
Attila Kinali
--
It is upon moral qualities that a society is ultimately founded. All
the prosperity and technological sophistication in the world is of no
use without that foundation.
-- Miss Matheson, The Diamond Age, Neil Stephenson
In message 20161102104103.0c58d35a72b7b36253b3d6b2@kinali.ch, Attila Kinali writes:
I still would like to try to build my own atomic clock at some point,
even if it would be a quite costly, and a many years project.
If you like lasers, build an ion trap.
If you only like lasers a little bit, build an optically pumped standard.
If you really like lasers, build a fountain.
If you are more chemically inclined, there are a ton of gasses you
can work with, methane, amonia, CO2 etc.
The one thing nobody has done or even tried yet, (as far as I know),
is optically excite a solid crystal.
--
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.