On 12/01/11 01:06, scmcgrath@gmail.com wrote:

As it has been pointed out before, the failure of a tube may be from any
number of issues, including the failure of the ionizer of the
masspectrometer for instance. Restoring a tube may require cleaning or
replacement several parts. Another failure may be the ion-pump.

Regardless it may take some effort to clean things up.

It's in the arcives if you search for it.

Cheers,
Magnus

Scott,

Just being a "high vacuum nut" may not be enough.  Most vacuum
devices have "getters" engineered into them.  These are usually
reactive coatings applied to the cavity wall that react with or
absorb trace gasses to maintain the vacuum.  They are made of
evaporated thin-films of exotic mixtures like zirconium and vanadium,
aluminum, cobalt, etc...  If you've ever seen a glass vacuum tube
with a "mirror top" coating, you've seen a getter.

The act of opening them in a high vacuum environment, may not destroy
them, but introducing them to an any kind of atmosphere to perform a
repair may destroy the getters, and render the life of the device
quite short.

Rob
Ex-USGS Isotope branch "Vacuum Nut"

On Jan 11, 2011, at 6:06 PM, scmcgrath@gmail.com wrote:

This is a popular FAQ that Cs engineers hear.

The correct answer (at least for HP/Agilent CBTs)
is that there is plenty of Cs in the tube, and
they don't fail because they ran out of Cs.  Something
else will always wear out first.

Regarding the general idea of rebuilding CBT's:

a used CBT is so "cesiated" that it is not practical
to rebuild it even on the regular CBT line.  Even
if it were, it is unlikely a time nut would have
the necessary high vacuum equipment.  It is pretty
serious stuff.  You also need to be able to laser
weld the case together when you are finished.  Sure
seems like a "don't try this at home thing".

We're still waiting to see if they can figure out
how make 5071 CBT's on the east coast, let alone
someone's garage.

Rick Karlquist N6RK

On 1/11/2011 4:06 PM, scmcgrath@gmail.com wrote:

Oh yes, after I ran into my first dead Cs and found the
price of a replacement tube, you bet I wondered if they
could be refilled. I mean, the same hp also made printers
and you can refill them. What could be more natural. But
a couple of events over the years dashed all my hopes.

First I got my first opened Cs tube, from an 5061A that
Corby had. I have no idea how you'd open one, do the
brain surgery, and put it back together with the same
purity and mechanical precision that it first was.

Second, running out of cesium is not always the problem.
Think about where the cesium goes. When a printer runs
out of ink it's because it has printed tens of thousands of
pages. The pages take the ink with them and the printer
stays fairly clean. But where does the cesium go? It's all
still inside, every single atom of it. On the walls, on the
magnets, in the getter, and stuck on the dynodes of the
electron multiplier. So even if you could add more Cs to
the oven on one end, perhaps the harder job would be to
clean up all the cesium residue that's everywhere else.
It would be like adding more and more fresh oil to a car
but never emptying the oil pan.

Third, I got a tour of the hp factory in Santa Clara where
the tubes were made. I was humbled. The clean room, the
precision, the tiny EM, the vacuum stuff, the oven assembly,
the one-time diaphragm that seals the oven pin hole, the
wiring, the testing, the people, the decades of knowledge,
the infrastructure.

Instead what would be fun is for someone to try to make
their own tube. Save yourself some work and re-use all the
electronics of a 5061A. But make your own tube. Even
re-use as many parts of an existing tube as you want. But
make your own instead of trying to put Humpty Dumpty
back together again.

/tvb

It may not be necessary to open a tube to renew the supply of an
alkali metal.
I remember an experiment where an incandescent light bulb was dipped
into molten sodium chloride in an iron vessel.
The filament was run and a voltage between the filament and the iron
vessel caused sodium ions to migrate through the glass
into the bulb. Sodium accumulated in the bulb.
It is obviously a slow process, but then you did not need to put much
Cs in the bulb.

Why not use it to recharge an alkali metal lamp?

cheers, Neville Michie

On 12/01/2011, at 11:06 AM, scmcgrath@gmail.com wrote:

I suppose that would be possible if a C beam standard worked like a rubidium
reference, but alas, they are different in virtually all respects.

Think of the C beam as having a small kettle full of cesium that is put
on a low simmer.  The kettle keeps the cesium molten, and bubbling up minute
amounts of cesium vapor.

How are you going to refill the kettle when it lives in the middle of
a hard vacuum chamber?  The best you could do with your technique (assuming
it is even possible) is to coat the walls of the vacuum chamber with cesium...

Kind of like trying to fill the gas tank by hosing the car down with gasoline.

Besides, if HP can be believed, the kettle never runs out of cesium before
the receiving end of the tube gets completely choked on waste cesium metal.
That waste cesium needs to be removed, and the electron multiplier needs to
be restored, at a minimum.... and the ion pump is probably full up too.

-Chuck Harris

Neville Michie wrote:

It sounds like you need to dip a corner of the device in liquid nitrogen
and allow the metal to evaporate and condense in the cold corner.
Or is it sublimation.
I do not know how long it would take.
cheers, Neville Michie

On 13/01/2011, at 11:31 PM, Chuck Harris wrote:

Really interesting thread. About a year ago on this thread the same
discussion occurred.
Several thoughts along these lines and frankly I know little accept for what
I read here and online.
I would agree the CS never runs out. Accept for one minor point. We tend to
get these things way beyond HPs end dates by many years. So is it really
true?
This threads a bit different then the last one. The last one described
opening the internals and various effects from trying to refill the kettle.
This would be the first insight that I have in the fact that the systems
polluted perhaps.
Regards

On Thu, Jan 13, 2011 at 7:31 AM, Chuck Harris cfharris@erols.com wrote:

On 1/13/11 4:59 AM, paul swed wrote:

The mfr end date is a "guaranteed to work under all conditions and usage
patterns" date.  I could easily see the various mechanisms leading to
end of life proceeding at different rates depending on use, piece to
piece variation, etc.

You might find it interesting to look up the vapor pressure of
cesium at room temperature.

To get the cesium to transport from where it has deposited to your
cold corner would require heating the whole tube up to where the
cesium would vaporize.  I can't help but think that heating everything
in the tube that hot might cause other collateral damage... and the
cesium would certainly go and plate out on even more exciting places
than it did in normal operation.  That might not be a good thing.

I think this is a pay-to-play sort of thing.  If you want to play
with a C-beam, you are going to have to pay.  If you want one that
works like new, unless you are lucky, you might have to pay a lot.

-Chuck Harris

Neville Michie wrote:

Sure it would be lots of fun making your own tube or rebuilding a bad one.

This, my favorite internet video, is not exactly about caesium beam
tubes, but at least shows some of the required skills, as well as how
much fun it can be.

http://dailymotion.alice.it/video/x3wrzo_fabrication-dune-lampe-triode_tech

Adrian

Tom Van Baak schrieb:

As I said last go-round, I think the chances of rebuilding an HP Cs tube
are slim to none.

BUT, if you were really dedicated, I think you could build up the physics
package from pretty much standard stuff, like the Kimball Physics gun
parts and Conflat SS vacuum hardware, etc.  Check Duniway.

I'd start by reviewing the old, academic papers. Much of the electronics
can be bought on eBay as instruments now.

Yes, it'd be refrigerator size, but it is do-able, IMO.

Best,

-John

==================

]

Hi

I certainly agree with that. The tubes in a "portable" cesium are done so
they fit inside a specific box. In a lot of ways bigger is better if you are
going to do it yourself. It would not at all be a trivial undertaking. It
also would not be cheap.

Cs standards with dead tubes are indeed pretty cheap. I think I'd start with
the electronics from one of them. Being able to do the tube stuff without
having to do the electronics at the same time should make things a bit
easier. You could swap out the electronics for your own once the tube was
doing it's thing.

Bob

-----Original Message-----
From: time-nuts-bounces@febo.com [mailto:time-nuts-bounces@febo.com] On
Behalf Of J. Forster
Sent: Thursday, January 13, 2011 11:24 AM
To: Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] CS reservoir depletion

As I said last go-round, I think the chances of rebuilding an HP Cs tube
are slim to none.

BUT, if you were really dedicated, I think you could build up the physics
package from pretty much standard stuff, like the Kimball Physics gun
parts and Conflat SS vacuum hardware, etc.  Check Duniway.

I'd start by reviewing the old, academic papers. Much of the electronics
can be bought on eBay as instruments now.

Yes, it'd be refrigerator size, but it is do-able, IMO.

Best,

-John

==================

]

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.

huh?

Paul,

What I've heard is that the lifetime of the 5071A high-performance
tube is around 7 years (when the cesium runs out) and the lifetime
of the standard tube is up to 20 years (when the EM fails). There
are other failure modes too so YMMV. Not sure about 5061A and
other tubes. There are variations within the 5071A tube as well
(including the short-lived turbo tube), so take this only as a rough
estimate (but do see the chart in paper10.pdf below).

As you may know the high-perf tubes have higher performance
simply because they use a much higher flux of atoms (beam
clock noise is a simple function of flux) and so they run out of
"gas" proportionally faster. Like a candle burning twice as bright,
or for you Neil fans, it's better to burn out than to fade away.

But there's lots of data on this subject since most of the national
timing laboratories use 5071A in quantity and they collect all
the internal performance data that the 5071A makes available
over the RS232 port. Some papers on the subject include:

End-of-life Indicators for NIMA's High-performance
Cesium Frequency Standards

http://tycho.usno.navy.mil/ptti/ptti2002/paper10.pdf

Maintenance of HP 5071A Primary Frequency Standards
at USNO
http://tycho.usno.navy.mil/ptti/1997/Vol%2029_06.pdf

An Automated Alarm Program for HP5071A Frequency
Standards
http://tycho.usno.navy.mil/ptti/ptti99/PTTI_1999_649.PDF

/tvb

Hi Tom been quite a while hope you are well.
The never run out comments, not from me. Look at the previous thread I
tagged onto. My humor is that most of the CS tubes we get are very long in
the tooth usually way past whatever anyone would say they are good for.

However my 5065 Rb is still going strong, knock on wood after 2 X what was
stated for life.
Unfortunately my 5061 was actually dead on arrival. But you take your risk
at $125, right?

Didn't really matter that it did not work as much as I might have liked it
to. I learned a heck of a lot from trying to get it to. Also from support on
this list. If it had worked I would not have really learned a thing.
Maybe I will find a tube one day. But pretty sure I won't be drilling a hole
and pouring some CS into it.

Oddly enough I picked up a HP super-duper pico amp meter and source and when
the dust settles on several projects will hook it up just for the heck of it
to see if there is even a drop of I beam current hiding behind some magnets
in the tube.
Regards
Paul
WB8TSL

On Thu, Jan 13, 2011 at 2:30 PM, Tom Van Baak tvb@leapsecond.com wrote:

On 13/01/11 17:24, J. Forster wrote:

Many of the pieces of a physical package can either be found off the
shelf (ionizer/masspectrometer) or at least be hammered up fairly easily
(microwave link) even if performance is far optimum. The cesium oven
should also be fairly buildable. The C-field coil could certainly be
built with some care. My-metal shields may take some effort. Outer
shield is a challenge for vacuum performance and there is such a thing
as high-vacuum nuts. Similarly the ionpump is off the shelf. The piece
that I would not expect to be easy to buy or build is the A and B
magnets which deflect wrong state atoms. Also, handle Cesium and
breaking the Cesium ampule may be a bit of a challenge to get right.

There is certainly be a bit of challenges to get something which works.
Being able to get good performance would take many many years of
experimentation and learning. The HP/Symmetricom efforts spans from the
60thies. Many steps of improvement, of which only some is found in
papers and patents. But they have left such traces too. There are many
practical solutions which can be learned from the archives.

The electronics could either be to reuse a HP5061 or whateer is
available, but most of it should not be all that hard depending on
background.

It would be a hell of a project. Just like building a H-maser.
In comparision a Rubidium is much easier.

Cheers,
Magnus

I'm not so sure handling the Cs is all that different from handling Na.
You basically distill it in glass from where you break the vial to where
it wants to ultimately be, under high vacuum.  Actually, moving Rb is
essentially the same too.

I'd imagine building a Cs unit might be a bit easier than an H MASER, but
not by much. Certainly a Rb is easier.

-John

==============

On 13/01/11 18:27, Bob Camp wrote:

Hacking existing hardware to achieve a digital steering of C-field
should not be too hard. The first patent I recall uses a RCA CD1802
processor for control. Essentially it adds a DDS, ADC (detector), DAC
(OCXO EFC and C-field control) and processor. It would replace the
normal modulated signal of typical cesium signals (12,6 MHz) and take
the signal prior to classical detectors.

Cheers,
Magnus

Magnus Danielson wrote:

HP once held an internal seminar several days long that covered
only the aspects of the CBT that were not public.  So realize that what
you know is the tip of the iceberg.

Rick Karlquist N6RK

On 13/01/11 22:55, Rick Karlquist wrote:

Oh yes. I expect that there is a lot of things to know that I don't know.

I expect that there is a gazillion things to know to get decent shape
beam going. Aiming for a "getting it to lock up" level is what a very
handy hobbyist may aim for and maybe attain after a lot of work. There
will be loads and loads of systematic effects, biases etc.

So no, I do not think even the entry level is simple... I'm not that
naive...

It took several decades of development for a large set of talented guys
to come to the HP5071A design. Much of the knowledge is certainly skills
of the art which isn't shared lightly... and isn't learned lightly either...

So I am fully aware that I see only a little of the iceberg.

Just reading up on the publically available information from the number
of design efforts made in various places should be humbling for anyone
doing the exercise. You may learn a lot without being able to design a
high performance system.

Cheers,
Magnus

J. Forster wrote:

Other than the "glassware", building an Rb is entirely possible
in your garage, at least if you are a certifiable time nut.
This is based on the HP 10816 mini-Rb I worked on circa 1980.
It would be even easier now.

The glassware is tricky only because you have to work with
stuff that is more like fused quartz than glass.  This is because
regular glass can't deal with Rb very well.

The other problem for the garage builder is that one of the Rb
isotopes is slightly radioactive.  Probably not OK to have
in your garage.

Rick Karlquist N6RK

Lead is slightly radioactive.  Presumably the person building the device
would either source the right isotope or just use an existing vapor
container from an old unit.  Of course if it was totally scratch built, I'd
still just buy the right isotope.

-Bob

On Thu, Jan 13, 2011 at 4:18 PM, Rick Karlquist richard@karlquist.comwrote:

The glassware part is outlined in Strong's "Proceedures in Experimental
Physics" as I remember. It takes some skill, but it's not insurmountable.

Best,

-John

=================

On 14/01/11 00:18, Rick Karlquist wrote:

To start with, Rb-87 has a half-life of 4,88E+10 years with negative
beta-decay, i.e. an electron.

It has been judged very hard to accumulate any large amounts of it in
the body to build up to a unsafe dosage... you would pee it out before
it got there...

Also, I already have it in the garage and does not feel overly scared by
it. I also have some Americum in a smoke-detector. There is also uranium
in the ground, causing background radiation.

Cheers,
Magnus

On 14/01/11 00:23, Robert Darlington wrote:

If you go down the classical route you need Rb-87 (x2) and Rb-85. Also,
you want buffer-gas.

A more modern route would skip two of the glass containers (the Rb-87
lamp and the Rb-85 filtering cell) and inject the right excitation
wavelength using a tuned laser diode. It would just create a different
set of problems, but if you do not aim for perfection at first, then it
should be handleable. So far the lasers I've seen capable of pulling it
off isn't that cheap, but I haven't looked too much at it and I am not a
tuneable laser expert... I would have to do a bit more reading up before
attempting anything in that direction.

Cheers,
Magnus

Not to mention radio calcium in your bones.

-John

=============

On 1/13/11 3:18 PM, Rick Karlquist wrote:

My glassblowing friends say that it's just a matter of getting
comfortable with the oxyhydrogen torch (with a colorless flame).  If you
can work with Pyrex and a oxyPropane, it's easier.  They all say that
this is a basic life skill that everyone should have.  Yeah, sure.

Pshaw.. we've all got Americium in our houses, what's the big deal. <grin>

My (17 yr old) daughter is intrigued by the whole discussion on the
rad-safe list about K40.  Do you sleep on top of, under, or next to your
partner to minimize radiation exposure.  Does the amount of banana
consumption of either person affect this? (as a father, I'm not so sure
I'm comfortable with the whole discussion. As far as I'm concerned,
she's taking a lead envelope to the dorms to sleep in.)

yes, all true, but this is what causes my wife to worry that she will
come home from work and find a crew in bunny suits outside our house.

When I was an undergrad at UCLA, the local chapter of the Committee to
Bridge the Gap made radiation measurements on the roof of Boelter Hall
(wherein there was a decommissioned reactor) and discovered "bigger than
nominal background" .  Their excitement was tempered when it was
discovered that the aggregate used in the concrete was granite from from
the local mountains, which has a moderately high concentration of
hornblende, and, hence has about double the usual background emissions.

So,

Has anyone priced a replacement for a 5061 tube lately?  I thought I saw
upgrade kits from one of the other vendors in magazine once.  Where does
that path take you?  Anyone?

Shawn

On Thu, 2011-01-13 at 15:02 +0100, Adrian wrote:

There seems to be a bunch of "standard" techniques, then it's just a lot
of practice. But, like cooking or sex, a good lab instructor is a big
help.

A lead sleeping might protect her from real, rather than imagined, risks.

YMMV,

-John

==============

On 1/13/11 2:24 PM, Magnus Danielson wrote:

and it's reporting on a list like this that moves info from the "known
only to the cognoscenti inside company X" to "known to the initiated few
who subscribe to time-nuts"

On 14/01/11 02:25, jimlux wrote:

Having had a party in Swedens first reactor R1, now de-commissioned
research and educational reactor, I kind of should have worried before.
Fact is... radiation wise it is one of the safer places to be, as they
have measured every square meter separately to ensure that it is only
background radiation left. They now use that reactor hall for dance and
music performances. Quite central in Stocholm actually...

We are straying too far away I fear. End story is that the small amounts
of Rubidium we play with isn't very dangerous radiation-wise. I worry
more about the fact that it would not be too nice to have direct contact
with it as it reacts hefty with water and the result of that isn't all
that nice. There is a thad of toxity too, but not very severly. I worry
more about the fumes from the PCBs I solder and the lead in the
solder... but usually not much at all.

It seems like suitable lasers for pumping Rubidium can be found cheap...
on ebay. Nice reference:
http://massey.dur.ac.uk/resources/pfgriffin/griffin_thesis.pdf
Points to Sharp GH0781JA2C, datasheet
http://www.chipcatalog.com/Sharp_Microelectronics/GH0781JA2C.htm
2,80 USD each on ebay... well, why not get some and play a little?

Cheers,
Magnus

Not lately I seem to remember $12K or 30K something crazy like that.
Somewhat out of an Amateurs budget. Though I should get the lotto any day
now.

On Thu, Jan 13, 2011 at 8:28 PM, Shawn Tayler shawn@xmtservices.net wrote:

That is so true. It always amazes to pick up a 30 year old
5061A and find that it still works. Sometimes the reason is
that it is already on its 2nd or 3rd replacement tube before
it went to surplus. In which case you're happy for years.
Other times it may be that the 5061A was used only very
intermittently and the tube is the low S/N original.

A real gem would be one that was kept in cs-off mode except
for a few hours once a month to keep the OCXO within some
loose cal lab spec. Even after decades it would be as good
as new.

For many frequency applications there is no reason to run
in full cs-locked mode. This is also true if you need good
short-term stability. The free-running OCXO in most Cs (and
GPSDO for that matter) are more stable short-term when the
loop is open.

/tvb

Tom
That is one thing I noticed even without the CS the system is very stable
with the Xtal.
My comment was tagging on to a previous one and I couldn't resist the fact
that I get might old stuff.
Good comment on the standard. Indeed I run my 5065 every month or so for a
day or two insuring its stable and no problems have or are cropping up.
My 5061 came from the Naval observatory. I just know the next hamfest or MIT
flea I will find a new tube for it for $10 or 20. Not to likely.
Regards

On Fri, Jan 14, 2011 at 1:01 AM, Tom Van Baak tvb@leapsecond.com wrote:

..."We're still waiting to see if they can figure out
how make 5071 CBT's on the east coast, let alone
someone's garage."...

Rick...what did you mean by "on the east coast"?   Just curious.

73, Jeff W3KL
 Jeffrey K. Okamitsu, PhD, MBA
+1-609-638-5402 US Mobile Phone
+1-240-421-0692 GSM Mobile Phone

From: Richard (Rick) Karlquist richard@karlquist.com
To: scmcgrath@gmail.com; Discussion of precise time and frequency measurement
time-nuts@febo.com
Sent: Thu, January 13, 2011 12:09:01 AM
Subject: Re: [time-nuts] CS reservoir depletion

This is a popular FAQ that Cs engineers hear.

The correct answer (at least for HP/Agilent CBTs)
is that there is plenty of Cs in the tube, and
they don't fail because they ran out of Cs.  Something
else will always wear out first.

Regarding the general idea of rebuilding CBT's:

a used CBT is so "cesiated" that it is not practical
to rebuild it even on the regular CBT line.  Even
if it were, it is unlikely a time nut would have
the necessary high vacuum equipment.  It is pretty
serious stuff.  You also need to be able to laser
weld the case together when you are finished.  Sure
seems like a "don't try this at home thing".

We're still waiting to see if they can figure out
how make 5071 CBT's on the east coast, let alone
someone's garage.

Rick Karlquist N6RK

On 1/11/2011 4:06 PM, scmcgrath@gmail.com wrote:

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

Hi,

I can get a 00105-6013 xtal oscillator that is the type used in the
5051A and 5065 standards.  Does it worth for a standalone frequency
standard or the more modern compact types such the miniature units from
the telco towers salvage coming from China are more convenient?
I realize that I need to provide both with a low noise power supply,
specially for the frequency control voltage, but the in modern ones the
supply issue is simpler and they give the (usually) more convenient 10
MHz output instead of 5 MHz.  I don't know if the HP unit is usually
quieter or more stable.
I also I know that it depends of the intended use. In this case it is
for my home lab which includes a compact Rb and a soon to be built GPSDO.

Regards,
Ignacio, EB4APL

El 14/01/2011 7:01, Tom Van Baak wrote:

In your dreams.

There was a very nice HP Cs there a few years ago, but it had a properety
tag that I recognized. I knew that unit had a known bad Cs tube, as I seen
it at a company surplus sale a month before,  but that didn't stop the guy
hawking it as "working" for well over $5K.

Caveat Emptor!!

-John

==============

Hi,

From: "Robert Lutwak" rlutwak@gmail.com

:-)
http://hal.archives-ouvertes.fr/docs/00/22/17/25/PDF/ajp-jphyscol198142C830.pdf

Bye,
Jean-Louis

I believe everything being discussed can be found in the 'public
domain', and therefore falls under the "Public Domain" definitions
ITAR (unless someone on here is privy to something that isn't!)
(120.18)

(I could be wrong, not a lawyer, disclaimer du jour, etc.)

--j

On Fri, Jan 14, 2011 at 8:55 AM, Robert Lutwak rlutwak@gmail.com wrote:

Hi

The 105 oscillator is a nice OCXO. I certainly would not throw one away.
There are indeed better parts out there. It all depends on what you are
trying to do.

The phase noise of the unit is not as good as some of the 10 MHz stuff. I
would not base a microwave synthesizer on one. It's short term stability is
a "depends on the one you have". Testing would be needed here. Aging wise it
should be pretty good. That assumes it was on power for a good part of it's
life. If it's been on the shelf for 20 years, you may need to run it for a
while ...

Bob

-----Original Message-----
From: time-nuts-bounces@febo.com [mailto:time-nuts-bounces@febo.com] On
Behalf Of EB4APL
Sent: Friday, January 14, 2011 10:05 AM
To: time-nuts@febo.com
Subject: Re: [time-nuts] CS reservoir depletion

Hi,

I can get a 00105-6013 xtal oscillator that is the type used in the
5051A and 5065 standards.  Does it worth for a standalone frequency
standard or the more modern compact types such the miniature units from
the telco towers salvage coming from China are more convenient?
I realize that I need to provide both with a low noise power supply,
specially for the frequency control voltage, but the in modern ones the
supply issue is simpler and they give the (usually) more convenient 10
MHz output instead of 5 MHz.  I don't know if the HP unit is usually
quieter or more stable.
I also I know that it depends of the intended use. In this case it is
for my home lab which includes a compact Rb and a soon to be built GPSDO.

Regards,
Ignacio, EB4APL

El 14/01/2011 7:01, Tom Van Baak wrote:

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

Hi

Through the flips and flops of HP => Agilent => Symmetricom various products
have changed badges and locations. They appear to be consolidating cesium
standard production at the old FTS plant in Beverly(?) MA. Ultimately I
suspect they will redesign the product line to "rationalize" it. That should
be fun to watch. It would be much less fun to be caught in the middle of.

Bob

-----Original Message-----
From: time-nuts-bounces@febo.com [mailto:time-nuts-bounces@febo.com] On
Behalf Of Jeffrey Okamitsu
Sent: Friday, January 14, 2011 9:18 AM
To: Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] CS reservoir depletion

..."We're still waiting to see if they can figure out
how make 5071 CBT's on the east coast, let alone
someone's garage."...

Rick...what did you mean by "on the east coast"?   Just curious.

73, Jeff W3KL
 Jeffrey K. Okamitsu, PhD, MBA
+1-609-638-5402 US Mobile Phone
+1-240-421-0692 GSM Mobile Phone

From: Richard (Rick) Karlquist richard@karlquist.com
To: scmcgrath@gmail.com; Discussion of precise time and frequency
measurement
time-nuts@febo.com
Sent: Thu, January 13, 2011 12:09:01 AM
Subject: Re: [time-nuts] CS reservoir depletion

This is a popular FAQ that Cs engineers hear.

The correct answer (at least for HP/Agilent CBTs)
is that there is plenty of Cs in the tube, and
they don't fail because they ran out of Cs.  Something
else will always wear out first.

Regarding the general idea of rebuilding CBT's:

a used CBT is so "cesiated" that it is not practical
to rebuild it even on the regular CBT line.  Even
if it were, it is unlikely a time nut would have
the necessary high vacuum equipment.  It is pretty
serious stuff.  You also need to be able to laser
weld the case together when you are finished.  Sure
seems like a "don't try this at home thing".

We're still waiting to see if they can figure out
how make 5071 CBT's on the east coast, let alone
someone's garage.

Rick Karlquist N6RK

On 1/11/2011 4:06 PM, scmcgrath@gmail.com wrote:

Cs

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Hi

I suspect you are a lot more likely to come up with a new tube by talking to
Bert before he gets rid of his inventory....

Bob

-----Original Message-----
From: time-nuts-bounces@febo.com [mailto:time-nuts-bounces@febo.com] On
Behalf Of paul swed
Sent: Friday, January 14, 2011 9:10 AM
To: Tom Van Baak; Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] CS reservoir depletion

Tom
That is one thing I noticed even without the CS the system is very stable
with the Xtal.
My comment was tagging on to a previous one and I couldn't resist the fact
that I get might old stuff.
Good comment on the standard. Indeed I run my 5065 every month or so for a
day or two insuring its stable and no problems have or are cropping up.
My 5061 came from the Naval observatory. I just know the next hamfest or MIT
flea I will find a new tube for it for $10 or 20. Not to likely.
Regards

On Fri, Jan 14, 2011 at 1:01 AM, Tom Van Baak tvb@leapsecond.com wrote:

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Bob, is there any indication in you have to "run it for a while" depends
on how long it has been off?

Does a crystal oscillator that has been off for 50 years, take longer than
one that has been off for a week?

I ask because the 1818.18 Hz crystal in a LORAN-A Test Set I picked up is
currently running at about 1818.48 Hz. It's been off since about 1945.

Best,

-John

===============

[snip]
That assumes it was on power for a good part of

Hi

There is a lot of data that says crystals "relax" while off power. The older
they are (the older the process) the more likely they are to do so. The net
effect is that they will move much faster on a per day basis than you would
expect them to. They will eventually calm down, but it can take months.
Things like mounting stress (TCE miss match), and thermally introduced
changes in junk equilibrium are the two most commonly claimed sources.

One example is the GR standard I have in the basement. It's now down to a
sub 1.0x10^-11 per day sort of aging rate. When I fired it up, it was moving
more than 1.0x10^-8 per day.

As with any rule like this, there will indeed be parts that break the rule.

Bob

-----Original Message-----
From: time-nuts-bounces@febo.com [mailto:time-nuts-bounces@febo.com] On
Behalf Of J. Forster
Sent: Friday, January 14, 2011 12:45 PM
To: Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] CS reservoir depletion

Bob, is there any indication in you have to "run it for a while" depends
on how long it has been off?

Does a crystal oscillator that has been off for 50 years, take longer than
one that has been off for a week?

I ask because the 1818.18 Hz crystal in a LORAN-A Test Set I picked up is
currently running at about 1818.48 Hz. It's been off since about 1945.

Best,

-John

===============

[snip]
That assumes it was on power for a good part of

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Bob Camp wrote:

My experience with 10811's is that it didn't matter much whether
they have been off for a week or a year as far as settling down
was concerned.  Also "on and off" effectively refers to the oven.
Turning the oscillator on and off while keeping the oven on
continuously has little effect.

Rick Karlquist N6RK

Hi

I've seen some 10811's in GPSDO's that take many weeks to settle below 3.0 x
10^-10 per day. It's rare to see one that's been on power recently behave
that way. The ones I'm looking at have been off power for years and stored
in an outdoor shed (no heat / cooling / humidity control).

Bob

-----Original Message-----
From: time-nuts-bounces@febo.com [mailto:time-nuts-bounces@febo.com] On
Behalf Of Rick Karlquist
Sent: Friday, January 14, 2011 1:34 PM
To: Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] CS reservoir depletion

Bob Camp wrote:

My experience with 10811's is that it didn't matter much whether
they have been off for a week or a year as far as settling down
was concerned.  Also "on and off" effectively refers to the oven.
Turning the oscillator on and off while keeping the oven on
continuously has little effect.

Rick Karlquist N6RK

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On 1/14/11 6:55 AM, Robert Lutwak wrote:

http://www.pmddtc.state.gov/regulations_laws/itar_official.html

I don't think so..
I looked through the current USML, and the word cesium doesn't appear in
it.  Spaceflight qualified atomic frequency standards ARE on the USML,
but I didn't see anything in there about standards for terrestrial use.
Might have missed it, or maybe it's a "dual use" and controlled under
the EAR, not ITAR?

On 1/14/11 8:12 AM, Jean-Louis Noel wrote:

Sadly, it has been made abundantly clear to me and my colleagues that
merely because something is published in the open literature does not
make it export-control free.  We are specifically cautioned that
pointing someone to a set of papers in a particular area falls in the
category of "providing technical assistance with the design of defense
articles", for which an export license is needed.

If you come at it with very clean hands.. purely research into
fundamental scientific principles.. then you are pretty safe, but as
soon as you start talking about design and build specifics, or
identifying and ranking alternatives, then you're in dangerous
territory.  (speaking here ONLY of things that go into space, since
unless specifically exempted, pretty much anything in space is a
"defense article")

In message 4D30BE89.8050803@earthlink.net, jimlux writes:

The depressing thing is that is almost word for word what a russian
atomic physicist said in 1989 at the "Global Issues for an Open
World" conference here in Copenhagen.

Poul-Henning

--
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.

Hi

Well that crosses off any discussion of Tang as a breakfast drink....

(You would indeed need to be fairly old to remember the TV commercials
selling it based on it's space connection).

Bob

-----Original Message-----
From: time-nuts-bounces@febo.com [mailto:time-nuts-bounces@febo.com] On
Behalf Of jimlux
Sent: Friday, January 14, 2011 4:22 PM
To: time-nuts@febo.com
Subject: Re: [time-nuts] CS reservoir depletion

On 1/14/11 8:12 AM, Jean-Louis Noel wrote:

http://hal.archives-ouvertes.fr/docs/00/22/17/25/PDF/ajp-jphyscol198142C830.
pdf

Sadly, it has been made abundantly clear to me and my colleagues that
merely because something is published in the open literature does not
make it export-control free.  We are specifically cautioned that
pointing someone to a set of papers in a particular area falls in the
category of "providing technical assistance with the design of defense
articles", for which an export license is needed.

If you come at it with very clean hands.. purely research into
fundamental scientific principles.. then you are pretty safe, but as
soon as you start talking about design and build specifics, or
identifying and ranking alternatives, then you're in dangerous
territory.  (speaking here ONLY of things that go into space, since
unless specifically exempted, pretty much anything in space is a
"defense article")

time-nuts mailing list -- time-nuts@febo.com
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and follow the instructions there.

Hi

Not to mention some conversations to the effect that indeed ITAR did force
the Russians to develop their own Space qualified Cs standards.

Bob

-----Original Message-----
From: time-nuts-bounces@febo.com [mailto:time-nuts-bounces@febo.com] On
Behalf Of Poul-Henning Kamp
Sent: Friday, January 14, 2011 4:36 PM
To: Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] CS reservoir depletion

In message 4D30BE89.8050803@earthlink.net, jimlux writes:

The depressing thing is that is almost word for word what a russian
atomic physicist said in 1989 at the "Global Issues for an Open
World" conference here in Copenhagen.

Poul-Henning

--
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.

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Tang probably made recycled urine palatable.  :))

-John

==================

Hi,

From: "jimlux" jimlux@earthlink.net

I can't imagine they could have done such mistake!

http://www.dtic.mil/cgi-bin/GetTRDoc?Location=U2&doc=GetTRDoc.pdf&AD=ADA509345
(second page)
http://tycho.usno.navy.mil/ptti/ptti2001/paper2.pdf

Bye,
Jean-Louis

Thank you Bob,

I think I'll get it, just to have another quality oscillator.  About its
aging I think it is new, probably a spare unit. since there are not
signs of any solder on the pins.

Best regards,
Ignacio

El 14/01/2011 18:11, Bob Camp escribió:

On Jan 14, 2011, at 1:45 PM, "Bob Camp" lists@rtty.us wrote:

Tang is a good example of a dual use technology(?).  No ITAR worries, just dept of commerce.  Unless you had some scheme for turning it into a weapon....  A prospect that is frightening to contemplate.

Tang was a WMD (Weapon of Massive Disgust) in and of itself.

-John

============

On Jan 13, 2011, at 5:18 PM, Rick Karlquist wrote:

I used to perform Rb/Sr geochronology "wet bench" chemistry in
college.  Rb-87 has a half-life on the order of ~48.8 billion years.
Several multiples of the estimated age of the universe.  The
potassium-40 in your own body is a much greater threat, followed by
C-14, and various natural sources, smoke detectors, camping lantern
mantles, etc... I understand the average person has several thousand
K40 decay events in their body per second.

Handling pure Rb is another thing entirely.  It is quite moisture
sensitive / pyrophoric, and tends to form shock sensitive peroxides
even when submerged under oil.  You really need to store the stuff in
a vacuum, or under an inert atmosphere.  But since we're also
discussing Cesium, I should point out that it is actually far worse
in this regard.  You could probably safely handle a small quantity of
Rb in a home lab environment for a short period of time.  Pure Cesium
would be a significant risk.

Rob

I don't know the number od K-40 decays per second, but it's certainly
non-trivial. Asw a freshman science project, I went into a chamber made
out of pre-atomic age battleship armor plate and had the K eminations
counted with a scintillator and MCA. From that measurement, we were able
to determine my "lean body mass".

I think any pure alkali metal basically has to be handled in a good vacuum
and moved around by distillation. It's easy enough as you are concerned
with grams, at most, not pounds of the stuff.

-John

==============

You obviously didn't see the Myth Busters episode where they used
several pounds of sodium to bust a bathtub.

Joe Gray
W5JG

Hi Robert,

From: "Robert Vassar" rvassar@rob-vassar.com

As you can see on page 28 vials remains untouched till everythings are in
place
and else broken.

http://jila01.colorado.edu/pubs/thesis/bennett/ch3.pdf
For a vial of cesium check ebay 280612515679

Bye,
Jean-Louis

In my undergraduate days, you could buy blocks of metallic Na from lab
supply. It was common fun to walk out onto the Harvard Bridge at night and
throw it into the Charles River. A routine hack.

When I said "handle" I meant get it from a sealed glass vial into another
place, in a controlled fashion.

FWIW,

-John

===============

Greg-

I, for one would be very willing to take a chance on one or two tubes
and see if there is any life left in them, but sadly I live in Va.

I have e-mailed a friend in Boulder to see if he ever heads out in
your direction but I don't think he does very often.

Please keep me in mind if you uncover a way to address the shipping
issue or if another steps up to buy the lot, as I would be willing to
contact them as well.

Regards,
-Brian Justin,  WA1ZMS
Forest, VA

On Jan 15, 2011, at 8:07 AM, "gbusg" gbusg@comcast.net wrote:

I doubt the shipping issue is really problematic. The amount of Cs is so
small and so well contained it presents no real hazzard.

If you want to be on the safe side, pack the tubes really well and ship
them UPS or FedEx Ground.

FWIW,

-John

=============

Greg,
I'm going to be in the area next month and might be able to pick some up and redistribute them if that is of any assistance.

If I can end up with a clock somehow, I'd be interested in that too.

Bob

On Jan 15, 2011, at 12:33 PM, "J. Forster" jfor@quik.com wrote: