So what’s inside that Cs Beam Tube anyway?
More eye candy for the cesium nuts -- the center of a cesium beam tube is the large copper Ramsey microwave cavity. Each generation of cesium standard uses a different design. The 5 specimens seen here came from Corby Dawson, who's probably hacked open more Cs tubes than all of us put together.
http://www.leapsecond.com/pages/cspeak/cesium-tube-ramsey-cavity-collection.jpg
So, Skip, if you have the time, break open another dead tube and keep removing layers until you expose the copper cavity itself.
The first commercial cesium standard was the Atomichron, made by the National Company in the late 50's. It's 10x larger than a 5061A. Some photos here, including visible parts of the monster beam tube:
http://www.leapsecond.com/museum/nc2001/
http://www.ieee-uffc.org/main/history-atomichron.asp
/tvb
On 10/31/16 3:28 PM, Richard (Rick) Karlquist wrote:
The ghost of Jack Kusters is now spinning in his grave on
this Halloween night. Jack was a fairly opinionated
guy and it didn't take much to get him excited.
Jack used to rail against people who asked this naive
question. There are any number of reasons why this
doesn't make sense. One major one is that everything
in the tube is thoroughly "cesiated" as Jack put it.
Another is: how do you determine which parts to replace?
Another is: is this economically feasible?
This is a classic question on small volume manufacturing (which I'm sure
these tubes are)..
The only "rebuildable" (vacuum) tubes I've seen are things like very
high power transmitting tubes, high voltage rectifiers, and high power
ignitrons or mercury arc rectifiers. All in the "hundreds of kV" or
"hundreds of kW" kind of range. I think they can rebuild smaller
transmitting tubes (10-20 kW), too.
I've seen a 1930s-40s era Cockroft Walton generator with not just
rebuildable rectifiers, but it's not even sealed: you run the
(diffusion) vacuum pump when you're operating it. The other things are
not exactly a tube, but things like pelletrons, dynamitrons, and
febetrons also tend to have a vacuum pump associated with them.
In this case, there are "user serviceable" parts inside - either because
they're mechanical devices, or because there's a fairly high probability
of internal localized and repairable damage from a flashover.
Skip
I added the pix to your fine commentary. Plus Toms pix. But its now a 3MB
file. Yes above the oven is the first state selector magnet. Never ever
thought I would see this clarity and level of detail. Not sure there is any
way to see the photo multiplier. I believe that would be a set of elements
that were in the same vacuum as the rest of the tub. Some place close to
the ionizer. I know what normal photo multipliers look like but suspect
this will not look like those.
Thanks for making my day. Now I know how to work on Frankenstein's brain.
Well maybe not right now.
Regards
Paul
WB8TSL
On Mon, Oct 31, 2016 at 7:41 PM, jimlux jimlux@earthlink.net wrote:
On 10/31/16 3:28 PM, Richard (Rick) Karlquist wrote:
The ghost of Jack Kusters is now spinning in his grave on
this Halloween night. Jack was a fairly opinionated
guy and it didn't take much to get him excited.
Jack used to rail against people who asked this naive
question. There are any number of reasons why this
doesn't make sense. One major one is that everything
in the tube is thoroughly "cesiated" as Jack put it.
Another is: how do you determine which parts to replace?
Another is: is this economically feasible?
This is a classic question on small volume manufacturing (which I'm sure
these tubes are)..
The only "rebuildable" (vacuum) tubes I've seen are things like very high
power transmitting tubes, high voltage rectifiers, and high power ignitrons
or mercury arc rectifiers. All in the "hundreds of kV" or "hundreds of
kW" kind of range. I think they can rebuild smaller transmitting tubes
(10-20 kW), too.
I've seen a 1930s-40s era Cockroft Walton generator with not just
rebuildable rectifiers, but it's not even sealed: you run the (diffusion)
vacuum pump when you're operating it. The other things are not exactly a
tube, but things like pelletrons, dynamitrons, and febetrons also tend to
have a vacuum pump associated with them.
In this case, there are "user serviceable" parts inside - either because
they're mechanical devices, or because there's a fairly high probability of
internal localized and repairable damage from a flashover.
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/m
ailman/listinfo/time-nuts
and follow the instructions there.
On Mon, 31 Oct 2016 14:50:51 -0700
ed breya eb@telight.com wrote:
It's a shame that they're not built in such a way that just the wear-out
parts could be replaced, and not wasting all the rest of the design and
craftsmanship that's probably just fine.
Because it's not that easy. We are talking about a high vacuum system
here. While you can get a vacuum tube working with a simple rotary
pump. You can even have something like an ion pump to make the vacuum
a bit cleaner and make it perform better. But this will not work with
the level of vacuum you need for a Cs standard. A small finger print
left somewhere on something, will outgas for many months and make
the whole system perform an order of magnitude or two worse than speced.
Yes, Cs beam standards are not as finicky as the modern Cs fountains
or even worse the optical clocks, but they are still very sensitive.
It would be possible to make the tube such that you could change the
"consumables". But it would still take a skilled technician in a clean
lab with special equipment to do the maintenance. But I am not sure
whether it would be that much cheaper than a new tube. And you always
have the risk that something goes wrong and you have the scrap the
tube for good.
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
I remember when they made tubes in Santa Clara, they
would assemble them and do some tests without breaking
the Cs ampule. A fair percentage would fail and would
go to a machinist using a big lathe to cut
them open to be rebuilt. It was very important that
the Cs had not been released yet.
Rick
Hi
Quite literally 10’s of millions of dollars (back in the good old days) was
put into the idea of a rebuildable Cs tube or rebuilding ones that already
exist. The result was more people in the tube business for a while. They
never did come up with a rebuildable tube or a salvage process. Since the
“prize” was a few hundred million (US government refurbishments over
years and years) if it worked, economics was not the issue.
Bob
On Nov 1, 2016, at 6:51 AM, Attila Kinali attila@kinali.ch wrote:
On Mon, 31 Oct 2016 14:50:51 -0700
ed breya eb@telight.com wrote:
It's a shame that they're not built in such a way that just the wear-out
parts could be replaced, and not wasting all the rest of the design and
craftsmanship that's probably just fine.
Because it's not that easy. We are talking about a high vacuum system
here. While you can get a vacuum tube working with a simple rotary
pump. You can even have something like an ion pump to make the vacuum
a bit cleaner and make it perform better. But this will not work with
the level of vacuum you need for a Cs standard. A small finger print
left somewhere on something, will outgas for many months and make
the whole system perform an order of magnitude or two worse than speced.
Yes, Cs beam standards are not as finicky as the modern Cs fountains
or even worse the optical clocks, but they are still very sensitive.
It would be possible to make the tube such that you could change the
"consumables". But it would still take a skilled technician in a clean
lab with special equipment to do the maintenance. But I am not sure
whether it would be that much cheaper than a new tube. And you always
have the risk that something goes wrong and you have the scrap the
tube for good.
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.
In message 20161101115121.998d1e1b073c5a9d1658be30@kinali.ch, Attila Kinali writes:
It would be possible to make the tube such that you could change the
"consumables".
Wasn't PTB's long Cs advertised on them being able to replenish the
Cs reservoir while it was running ?
--
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.