Discussion:
WTS: Efratom PTB-100 Precision Timebase
(too old to reply)
Don@True-Cal
2018-07-07 01:56:56 UTC
Permalink
Time-Nuts Group,



For someone interested in working on the Rb package which I believe is the
FRK series. Worked great in my lab for years and recently started being real
slow to lock during power cycles and now won't lock at all. Not sure what
the fair asking price would be in this condition. Maybe someone has
repair/refurb experience with the Efratom FRK.



Contact me if interested.

Don



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Attila Kinali
2018-07-07 19:32:24 UTC
Permalink
On Fri, 6 Jul 2018 20:56:56 -0500
Post by ***@True-Cal
For someone interested in working on the Rb package which I believe is the
FRK series. Worked great in my lab for years and recently started being real
slow to lock during power cycles and now won't lock at all. Not sure what
the fair asking price would be in this condition. Maybe someone has
repair/refurb experience with the Efratom FRK.
It is likely that the lamp degraded to the point it doesnt produce enough
light anymore. People have reported that they could revive old lamps
by heating it up with a heat gun and let the rubidium condense again
at the nook where it is supposed to be.

Attila Kinali
--
<JaberWorky> The bad part of Zurich is where the degenerates
throw DARK chocolate at you.

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Don@True-Cal
2018-07-08 21:57:25 UTC
Permalink
Thanks Attila,

Yes, that is a procedure I know about. The lamp glow is purple and my lamp
monitor voltage is 6.36, not great but should be in the working range. The
issue I'm trouble shooting right now is the PS transition from supply
voltage, 28V in my case, to 17V after lamp ignition is not stateful. It
starts pulsing to 17V after ignition and the duty cycle slowly transitions
from mostly at 28V to mostly at 17V over time - never stays at 17V. The PS
is working correctly though because the photocell preamplifier output is
causing the pulsing. I have the oscillator trimmer cap set for symmetrical
frequency change 4Hz above and below 10MHz following the integrator EFC but
the EFC sweep is 6.5V to 13.5V and I would expect the low end should start
closer to <1V. Still reading the manual and studying the circuits.

Regards,
Don

-----Original Message-----
From: time-nuts <time-nuts-***@lists.febo.com> On Behalf Of Attila
Kinali
Sent: Saturday, July 07, 2018 2:32 PM
To: Discussion of precise time and frequency measurement
<time-***@lists.febo.com>
Subject: Re: [time-nuts] WTS: Efratom PTB-100 Precision Timebase

On Fri, 6 Jul 2018 20:56:56 -0500
Post by ***@True-Cal
For someone interested in working on the Rb package which I believe is
the FRK series. Worked great in my lab for years and recently started
being real slow to lock during power cycles and now won't lock at all.
Not sure what the fair asking price would be in this condition. Maybe
someone has repair/refurb experience with the Efratom FRK.
It is likely that the lamp degraded to the point it doesnt produce enough
light anymore. People have reported that they could revive old lamps by
heating it up with a heat gun and let the rubidium condense again at the
nook where it is supposed to be.

Attila Kinali
--
<JaberWorky> The bad part of Zurich is where the degenerates
throw DARK chocolate at you.

_______________________________________________
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ed breya
2018-07-10 00:30:13 UTC
Permalink
It's not necessarily a fault in the Rb physics - sometimes "regular"
circuit or component problems cause the grief.

I have three units kind of like this - "SPTB-100/LN-001," to be exact,
with 5 MHz out. As I recall, it's similar to the M-100, so close enough
to use some of its available schematics and info. I had a problem a few
years back with one that wouldn't lock, and found that a ceramic
capacitor in the VCOCXO PLL filter had gone bad - leaky, so it never
settled down. I could not ID the exact circuit or part because that's
one of the areas that differs quite a bit from the M-100. Replacing the
cap brought it back to normal operation.

I haven't searched for the "proper" manuals/schematics in a while. If
anyone knows of these being available, please let me know.

Ed

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Don@True-Cal
2018-07-11 12:54:33 UTC
Permalink
Thanks everyone for the insightful comments. I've been inspired by off-list
help to get this unit working primarily because of the quality of the
internal FRK. If nothing else, it has been a tremendous learning experience
and after numerous hours studying the manual and bench testing I find myself
knowing far more about optical pumping and Rb absorption lines than I
thought I ever wanted to know. I keep you posted if I have a breakthrough.

Regards,
Don

-----Original Message-----
From: time-nuts <time-nuts-***@lists.febo.com> On Behalf Of ed breya
Sent: Monday, July 09, 2018 7:30 PM
To: time-***@lists.febo.com
Subject: Re: [time-nuts] WTS: Efratom PTB-100 Precision Timebase

It's not necessarily a fault in the Rb physics - sometimes "regular"
circuit or component problems cause the grief.

I have three units kind of like this - "SPTB-100/LN-001," to be exact, with
5 MHz out. As I recall, it's similar to the M-100, so close enough to use
some of its available schematics and info. I had a problem a few years back
with one that wouldn't lock, and found that a ceramic capacitor in the
VCOCXO PLL filter had gone bad - leaky, so it never settled down. I could
not ID the exact circuit or part because that's one of the areas that
differs quite a bit from the M-100. Replacing the cap brought it back to
normal operation.

I haven't searched for the "proper" manuals/schematics in a while. If anyone
knows of these being available, please let me know.

Ed

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Magnus Danielson
2018-07-11 14:40:32 UTC
Permalink
Hi Don,

This is the benefit of the old beasts, as you fiddle around with them
you learn so much more than supply power, turn the EFC and go "and then
what?".

I still find that I need to study the details of optical pumping more.

Cheers,
Magnus
Post by ***@True-Cal
Thanks everyone for the insightful comments. I've been inspired by off-list
help to get this unit working primarily because of the quality of the
internal FRK. If nothing else, it has been a tremendous learning experience
and after numerous hours studying the manual and bench testing I find myself
knowing far more about optical pumping and Rb absorption lines than I
thought I ever wanted to know. I keep you posted if I have a breakthrough.
Regards,
Don
-----Original Message-----
Sent: Monday, July 09, 2018 7:30 PM
Subject: Re: [time-nuts] WTS: Efratom PTB-100 Precision Timebase
It's not necessarily a fault in the Rb physics - sometimes "regular"
circuit or component problems cause the grief.
I have three units kind of like this - "SPTB-100/LN-001," to be exact, with
5 MHz out. As I recall, it's similar to the M-100, so close enough to use
some of its available schematics and info. I had a problem a few years back
with one that wouldn't lock, and found that a ceramic capacitor in the
VCOCXO PLL filter had gone bad - leaky, so it never settled down. I could
not ID the exact circuit or part because that's one of the areas that
differs quite a bit from the M-100. Replacing the cap brought it back to
normal operation.
I haven't searched for the "proper" manuals/schematics in a while. If anyone
knows of these being available, please let me know.
Ed
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Gregory Beat via time-nuts
2018-07-07 22:30:45 UTC
Permalink
In 2008, G Molenkamp, VK3UM noted that of the 20 Efratom model FRS-C units he restored, component failure due to long heat exposure caused most of the failures.
http://www.vk3um.com/Rubidium%20rejuvination.pdf
He notes that some lamps had Rb splattered over the inside wall of the glass.
In these cases, the Rb material was not consolidated in the “pinch of the glass lamp”.
Using the “heat gun process” he was able to rejuvenate those Rb lamps.

w9gb
==
Post by ***@True-Cal
Time-Nuts Group,
For someone interested in working on the Rb package which I believe is the
FRK series. Worked great in my lab for years and recently started being real
slow to lock during power cycles and now won't lock at all. Not sure what
the fair asking price would be in this condition. Maybe someone has
repair/refurb experience with the Efratom FRK.
Contact me if interested.
Don
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Gregory Beat via time-nuts
2018-07-07 22:50:40 UTC
Permalink
At the 38th Annual Symposium on Frequency Control (1984), a presentation was given on the “Lifetime and Reliability of Rubidium Discharge Lamps for Use in Atomic Frequency Standards” by Aerospace Corp., Efraton-Ball, and EG&G.
https://ieeexplore.ieee.org/document/1537723/

The spattering of Rubidium on the lamp’s inside glass is discussed.

greg, w9gb
Sent from iPad Air
Post by Gregory Beat via time-nuts
In 2008, G Molenkamp, VK3UM noted that of the 20 Efratom model FRS-C units he restored, component failure due to long heat exposure caused most of the failures.
http://www.vk3um.com/Rubidium%20rejuvination.pdf
He notes that some lamps had Rb splattered over the inside wall of the glass.
In these cases, the Rb material was not consolidated in the “pinch of the glass lamp”.
Using the “heat gun process” he was able to rejuvenate those Rb lamps.
w9gb
==
Post by ***@True-Cal
Time-Nuts Group,
For someone interested in working on the Rb package which I believe is the
FRK series. Worked great in my lab for years and recently started being real
slow to lock during power cycles and now won't lock at all. Not sure what
the fair asking price would be in this condition. Maybe someone has
repair/refurb experience with the Efratom FRK.
Contact me if interested.
Don
_______________________________________________
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and fo
Magnus Danielson
2018-07-07 23:37:03 UTC
Permalink
Hi,
Post by Gregory Beat via time-nuts
In 2008, G Molenkamp, VK3UM noted that of the 20 Efratom model FRS-C units he restored, component failure due to long heat exposure caused most of the failures.
http://www.vk3um.com/Rubidium%20rejuvination.pdf
He notes that some lamps had Rb splattered over the inside wall of the glass.
In these cases, the Rb material was not consolidated in the “pinch of the glass lamp”.
Using the “heat gun process” he was able to rejuvenate those Rb lamps.
I later tried that method on my R&S XSRM rubidium, with good progress. I
have reported on that on the list way back. It took two attempts, one
just to realize that I needed to keep the pinch at the top, because that
is where the hot atoms go.

Essentially, the thin film of rubidium will consume too much of the
radiation to emit any useful amount of pumping light. Heating it has the
rubidium go into gas and then collect somewhere cold, so it's just about
making sure that somewhere cold isn't the glass where it is to emit light.

My XSRM have however other issues that I need to attend to.

Cheers,
Magnus
Post by Gregory Beat via time-nuts
w9gb
==
Post by ***@True-Cal
Time-Nuts Group,
For someone interested in working on the Rb package which I believe is the
FRK series. Worked great in my lab for years and recently started being real
slow to lock during power cycles and now won't lock at all. Not sure what
the fair asking price would be in this condition. Maybe someone has
repair/refurb experience with the Efratom FRK.
Contact me if interested.
Don
_______________________________________________
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and follow the instructions there.
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and follo
Dana Whitlow
2018-07-08 00:02:39 UTC
Permalink
Would't it be helpful to blow a gentle jet of cooler air on the tipoff
region during the
rejuvenation procedure, to encourage condensation there?

Dana
Post by Gregory Beat via time-nuts
Hi,
Post by Gregory Beat via time-nuts
In 2008, G Molenkamp, VK3UM noted that of the 20 Efratom model FRS-C
units he restored, component failure due to long heat exposure caused most
of the failures.
Post by Gregory Beat via time-nuts
http://www.vk3um.com/Rubidium%20rejuvination.pdf
He notes that some lamps had Rb splattered over the inside wall of the
glass.
Post by Gregory Beat via time-nuts
In these cases, the Rb material was not consolidated in the “pinch of
the glass lamp”.
Post by Gregory Beat via time-nuts
Using the “heat gun process” he was able to rejuvenate those Rb lamps.
I later tried that method on my R&S XSRM rubidium, with good progress. I
have reported on that on the list way back. It took two attempts, one
just to realize that I needed to keep the pinch at the top, because that
is where the hot atoms go.
Essentially, the thin film of rubidium will consume too much of the
radiation to emit any useful amount of pumping light. Heating it has the
rubidium go into gas and then collect somewhere cold, so it's just about
making sure that somewhere cold isn't the glass where it is to emit light.
My XSRM have however other issues that I need to attend to.
Cheers,
Magnus
Post by Gregory Beat via time-nuts
w9gb
==
Post by ***@True-Cal
Time-Nuts Group,
For someone interested in working on the Rb package which I believe is
the
Post by Gregory Beat via time-nuts
Post by ***@True-Cal
FRK series. Worked great in my lab for years and recently started being
real
Post by Gregory Beat via time-nuts
Post by ***@True-Cal
slow to lock during power cycles and now won't lock at all. Not sure
what
Post by Gregory Beat via time-nuts
Post by ***@True-Cal
the fair asking price would be in this condition. Maybe someone has
repair/refurb experience with the Efratom FRK.
Contact me if interested.
Don
_______________________________________________
To unsubscribe, go to http://lists.febo.com/mailman/
listinfo/time-nuts_lists.febo.com
Post by Gregory Beat via time-nuts
and follow the instructions there.
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listinfo/time-nuts_lists.febo.com
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Magnus Danielson
2018-07-08 00:08:16 UTC
Permalink
Hi Dana,
Post by Dana Whitlow
Would't it be helpful to blow a gentle jet of cooler air on the tipoff
region during the
rejuvenation procedure, to encourage condensation there?
Sure, if you manage to hold it that way.
In the XSRM case, the lamp sits in a metallic holder which you then put
a metallic lamp-extractor on, which together creates a thermal cooling
to the back-end of the lamp assembly compared to the clear glass end.
This essentially achieves the same effect.

Cheers,
Magnus
Post by Dana Whitlow
Dana
Post by Gregory Beat via time-nuts
Hi,
Post by Gregory Beat via time-nuts
In 2008, G Molenkamp, VK3UM noted that of the 20 Efratom model FRS-C
units he restored, component failure due to long heat exposure caused most
of the failures.
Post by Gregory Beat via time-nuts
http://www.vk3um.com/Rubidium%20rejuvination.pdf
He notes that some lamps had Rb splattered over the inside wall of the
glass.
Post by Gregory Beat via time-nuts
In these cases, the Rb material was not consolidated in the “pinch of
the glass lamp”.
Post by Gregory Beat via time-nuts
Using the “heat gun process” he was able to rejuvenate those Rb lamps.
I later tried that method on my R&S XSRM rubidium, with good progress. I
have reported on that on the list way back. It took two attempts, one
just to realize that I needed to keep the pinch at the top, because that
is where the hot atoms go.
Essentially, the thin film of rubidium will consume too much of the
radiation to emit any useful amount of pumping light. Heating it has the
rubidium go into gas and then collect somewhere cold, so it's just about
making sure that somewhere cold isn't the glass where it is to emit light.
My XSRM have however other issues that I need to attend to.
Cheers,
Magnus
Post by Gregory Beat via time-nuts
w9gb
==
Post by ***@True-Cal
Time-Nuts Group,
For someone interested in working on the Rb package which I believe is
the
Post by Gregory Beat via time-nuts
Post by ***@True-Cal
FRK series. Worked great in my lab for years and recently started being
real
Post by Gregory Beat via time-nuts
Post by ***@True-Cal
slow to lock during power cycles and now won't lock at all. Not sure
what
Post by Gregory Beat via time-nuts
Post by ***@True-Cal
the fair asking price would be in this condition. Maybe someone has
repair/refurb experience with the Efratom FRK.
Contact me if interested.
Don
_______________________________________________
To unsubscribe, go to http://lists.febo.com/mailman/
listinfo/time-nuts_lists.febo.com
Post by Gregory Beat via time-nuts
and follow the instructions there.
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_______________________________________________
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Gregory Beat via time-nuts
2018-07-08 16:39:46 UTC
Permalink
Magnus -
When I scan/read the 1984 IEEE document, “Lifetime and Reliability of Rubidium Discharge Lamps for Use in Atomic Frequency Standards”
by Aerospace Corp., Efraton-Ball, and EG&G.
https://ieeexplore.ieee.org/document/1537723/
The failure of the rubidium lamps used on early NAVSTAR satellites, was the reason for in-depth studies of the Rb lamp, its lifetime and failure mechanism.

greg
Post by Magnus Danielson
Hi -
I later tried that method on my R&S XSRM rubidium, with good progress. I
have reported on that on the list way back. It took two attempts, one
just to realize that I needed to keep the pinch at the top, because that
is where the hot atoms go.
Essentially, the thin film of rubidium will consume too much of the
radiation to emit any useful amount of pumping light. Heating it has the
rubidium go into gas and then collect somewhere cold, so it's just about
making sure that somewhere cold isn't the glass where it is to emit light.
My XSRM have however other issues that I need to attend to.
Cheers,
Magnus
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djl
2018-07-08 19:09:43 UTC
Permalink
Greg et.al. IEEE stuff is just too expensive for single purchase. I have
found, to my sorrow over 40 odd years, that they also do not contain
<real> information, that is, info of actual use, because some other
company or person might actually benefit. In other words, the papers are
markers in the sand.
Now, this is my own opinion, a bit harsh, admittedly. Of course the
citations do need to be mentioned.
BTW, any published material generated with government funds that is not
classified belongs to the people, and is not copyrighted. I wonder if
that includes IEEE papers? that is, if anyone buys one, it can be copied
or distributed without restriction?
Not being in the lawyer class, I can't say for sure...
Thanks
Don
Post by Gregory Beat via time-nuts
Magnus -
When I scan/read the 1984 IEEE document, “Lifetime and Reliability of
Rubidium Discharge Lamps for Use in Atomic Frequency Standards”
by Aerospace Corp., Efraton-Ball, and EG&G.
https://ieeexplore.ieee.org/document/1537723/
The failure of the rubidium lamps used on early NAVSTAR satellites,
was the reason for in-depth studies of the Rb lamp, its lifetime and
failure mechanism.
greg
Post by Magnus Danielson
Hi -
I later tried that method on my R&S XSRM rubidium, with good progress. I
have reported on that on the list way back. It took two attempts, one
just to realize that I needed to keep the pinch at the top, because that
is where the hot atoms go.
Essentially, the thin film of rubidium will consume too much of the
radiation to emit any useful amount of pumping light. Heating it has the
rubidium go into gas and then collect somewhere cold, so it's just about
making sure that somewhere cold isn't the glass where it is to emit light.
My XSRM have however other issues that I need to attend to.
Cheers,
Magnus
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--
Dr. Don Latham
PO Box 404, Frenchtown, MT, 59834
VOX: 406-626-4304


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jimlux
2018-07-08 20:00:20 UTC
Permalink
Post by djl
Greg et.al. IEEE stuff is just too expensive for single purchase. I have
found, to my sorrow over 40 odd years, that they also do not contain
<real> information, that is, info of actual use, because some other
company or person might actually benefit. In other words, the papers are
markers in the sand.
Depends a lot on what you're looking at. I make pretty heavy use of
such papers on a day to day basis.

It is true that of late, there's an awful lot of "we built this
specialized circuit as part of a multiproject wafer using tool sets that
you can only afford if you're a billionaire or get them as part of a
university" stuff out there, which makes it probably non-duplicateable,
but there's also a lot of useful things.

But the older papers I use a lot (like the one on making coupled line
filters) were probably viewed as just as exotic back in the late 50s
when making accurate microwave measurements was quite timeconsuming and
tedious.
Post by djl
Now, this is my own opinion, a bit harsh, admittedly. Of course the
citations do need to be mentioned.
BTW, any published material generated with government funds that is not
classified belongs to the people, and is not copyrighted. I wonder if
that includes IEEE papers? that is, if anyone buys one, it can be copied
or distributed without restriction?
Not precisely - But in general, much government sponsored research has
no copyright, and the notice will say as much in the journal.

That said, there's no obligation for IEEE to make it available for free.
And IEEE has no problem with authors providing a "pre-print" edition of
their current papers online on their own server.


It is easy to find the whole proceedings for that conference at a
government site:
http://www.dtic.mil/dtic/tr/fulltext/u2/a217381.pdf


Another way to get a free copy (but tedious) is to file a Freedom of
Information Act request - JPL gets lots of these every year asking for
"Document JPL D-12345" or similar.. and someone prints it out and sends
it (or, these days, they may even just send you a .pdf, if that meets
the requirements of the FOIA).

I would say that for "recent" (last 20 years) papers, most government
places have some sort of online repository (yes, it comes and goes,
NASA's repo disappeared for a while then came back).

It's the older material that's harder to come by (70s and 80s), mostly
because the keeper of the docs hasn't got back that far when scanning.
You can find "popular" docs that are requested a lot(e.g. the "Los
Alamos Primer"), but more obscure ones take a while.

The indexing is also sometimes a bit wonky - I find I need to try
different searches using parts of the title, or sometimes the report
number, or the author's name. But this particular one was easy - it was
in the first page of hits from Google.


Also, not all government funded research is "public". IN particular,
Small Business Innovative Research (SBIR) grants give the grantee
exclusive rights for a significant period (5 years??), and the reports
can contain proprietary information, and so are not subject to unlimited
distribution.

Similarly, University research that is funded by the government is
subject to the Bayh-Dole Act - the university retains title and rights
to the research. It depends on the specific grant/contract whether
reports of that research are subject to copyright or not.

Philosophically, the government does this to get something of value
without having to spend as much money on it, since the producer can then
sell it to others as well. More research done, less taxpayer dollars, etc.

Another reason taxpayer funded research might not be published is that
it uses a third party's proprietary information. If I do a bunch of
rocket engine tests (I wish!) on Acme Corp's special proprietary rocket
fuel mixture, I might be able to publish the test results, but not be
able to publish the analysis that provided the expected values, based on
the rocket fuel formulation.
Post by djl
Not being in the lawyer class, I can't say for sure...
Thanks
Don
Post by Gregory Beat via time-nuts
Magnus -
When I scan/read the 1984 IEEE document, “Lifetime and Reliability of
Rubidium Discharge Lamps for Use in Atomic Frequency Standards”
by Aerospace Corp., Efraton-Ball, and EG&G.
https://ieeexplore.ieee.org/document/1537723/
The failure of the rubidium lamps used on early NAVSTAR satellites,
was the reason for in-depth studies of the Rb lamp, its lifetime and
failure mechanism.
greg
Post by Magnus Danielson
Hi -
I later tried that method on my R&S XSRM rubidium, with good progress. I
have reported on that on the list way back. It took two attempts, one
just to realize that I needed to keep the pinch at the top, because that
is where the hot atoms go.
Essentially, the thin film of rubidium will consume too much of the
radiation to emit any useful amount of pumping light. Heating it has the
rubidium go into gas and then collect somewhere cold, so it's just about
making sure that somewhere cold isn't the glass where it is to emit light.
My XSRM have however other issues that I need to attend to.
Cheers,
Magnus
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Dana Whitlow
2018-07-08 22:47:01 UTC
Permalink
Don, I've noticed that in general IEEE retains copyright on most stuff they
publish.
I've been a member for more than 20 years, and this galls me. For an
organization
that purports to be for the good of mankind, they seem awfully stingy with
the
information they gather. But if you do acquire papers from IEEE, you are
generally
*not *authorized to publish or distribute it further without getting
explicit permission
(and probably paying for it).

Sometimes I wonder why I hang onto the organizaiton- perhaps it's because,
as
a retiree, I'm unable to subscribe to all the usual "freebie" rags. I
still very much
want to keep up with developments in my field.

Dana
Post by djl
Greg et.al. IEEE stuff is just too expensive for single purchase. I have
found, to my sorrow over 40 odd years, that they also do not contain <real>
information, that is, info of actual use, because some other company or
person might actually benefit. In other words, the papers are markers in
the sand.
Now, this is my own opinion, a bit harsh, admittedly. Of course the
citations do need to be mentioned.
BTW, any published material generated with government funds that is not
classified belongs to the people, and is not copyrighted. I wonder if that
includes IEEE papers? that is, if anyone buys one, it can be copied or
distributed without restriction?
Not being in the lawyer class, I can't say for sure...
Thanks
Don
Post by Gregory Beat via time-nuts
Magnus -
When I scan/read the 1984 IEEE document, “Lifetime and Reliability of
Rubidium Discharge Lamps for Use in Atomic Frequency Standards”
by Aerospace Corp., Efraton-Ball, and EG&G.
https://ieeexplore.ieee.org/document/1537723/
The failure of the rubidium lamps used on early NAVSTAR satellites,
was the reason for in-depth studies of the Rb lamp, its lifetime and
failure mechanism.
greg
Hi -
Post by Magnus Danielson
I later tried that method on my R&S XSRM rubidium, with good progress. I
have reported on that on the list way back. It took two attempts, one
just to realize that I needed to keep the pinch at the top, because that
is where the hot atoms go.
Essentially, the thin film of rubidium will consume too much of the
radiation to emit any useful amount of pumping light. Heating it has the
rubidium go into gas and then collect somewhere cold, so it's just about
making sure that somewhere cold isn't the glass where it is to emit light.
My XSRM have however other issues that I need to attend to.
Cheers,
Magnus
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--
Dr. Don Latham
PO Box 404, Frenchtown, MT, 59834
VOX: 406-626-4304
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