On 2019-05-06 10:00 AM,  Bob kb8tq kb8tq@n1k.orgwrote:

Why do you think I posed the question "Anybody feeling lucky (or
desperate!)?"?  Don't forget that all(?) newer Rb standards use an
integrated cell so it's a 'set' of one.  Whether that's the case here is
unknown, but not likely given the size of this cell.

The only Russian Rb company I've heard of is Kvarz.  Has anyone seen a
cell from one of their old units?

Ed

Hi

Ummm ….. errrr ….. the Efratom Rb’s use an integrated lamp plus one cell.

http://www.wriley.com/A%20Modern%20MIL%20Rubidium%20Frequency%20Standard.pdf http://www.wriley.com/A%20Modern%20MIL%20Rubidium%20Frequency%20Standard.pdf

There still are a lot of people doing the lamp plus two approach. One of many:

http://www.excelitas.com/Downloads/DTS_Frequency_Standards_RAFS.pdf http://www.excelitas.com/Downloads/DTS_Frequency_Standards_RAFS.pdf

Bob

As expected the seller doesn't know, but offered 2 cells for the price of one if further info on the cells he's offering can be provided.
Determining the cell filling would likely be somewhat interesting/challenging.
Absorption spectroscopy using a tunable ECDL comes to mind to sort out the Rubidium isotopes present.

Bruce

Anyone know the price of the Excelitas device? No, I'm not interested in
purchasing one, just curious. I assume it is hair-curling expensive.

On Monday, May 6, 2019, Bob kb8tq kb8tq@n1k.org wrote:

--
Homo sum humani a me nihil alienum puto.

In message CANy2iXqYLS38t7JVaO76VdHJ2PKvhBpiTtzQ85jNwnd+LPxVGQ@mail.gmail.com, "William H. Fite" writes:

In addition to a metric shit-load of money, you also need an ITAR
approval before they will sell you one.

--
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

Back a while ago it was in the “over a million dollars” range.  Like anything that
is designed for space use, the price is meaningless until you sort through what
kind of paperwork this or that program requires.

Bob

I suppose that shouldn't surprise me but, since I have neither ITAR
credentials nor a metric shit load of money, it's a good thing that I don't
want one.

On Monday, May 6, 2019, Poul-Henning Kamp phk@phk.freebsd.dk wrote:

--
Homo sum humani a me nihil alienum puto.

On 5/6/19 3:54 PM, Bob kb8tq wrote:

Yeah, this one:
Radiation
Hardened to withstand natural and manmade space environments, including
phase- continuous operation through transient radiation

is a pain.

The vibe is high, but not mindbending they don't say whether it's sine
or random. But as a comparison the usual cubesat qualification level is
14grms...

Who was Excelitas originally?  Salem, MA  - is it EG&G?

On 5/6/19 5:34 PM, William H. Fite wrote:

Category XV— Spacecraft and Related Articles

(e) Spacecraft parts, components, accessories, attachments, equipment,
or systems, as follows:
...
(9) Space-qualified cesium, rubidium, hydrogen maser, or quantum (e.g.,
based upon Al, Hg, Yb, Sr, Be Ions) atomic clocks, and specially
designed parts and components therefor;

But, there is an exception.. if you could get one with having been fully
tested:
Note 4 to paragraph (e): (1) A determination that a specific article (or
commodity) (e.g., by product serial number) is space-qualified by virtue
of testing alone does not mean that other articles in the same
production run or model series are space-qualified if not individually
tested. (2) “Article” is synonymous with “commodity,” as defined in EAR
§772.1. (3) A specific article not designed or manufactured for use at
altitudes greater than 100 km above the surface of the Earth is not
space-qualified before it is successfully tested. (4) The terms
“designed” and “manufactured” in this definition are synonymous with
“specially designed.”

Mother of God, really?

I had a friend, now of blessed memory, who was lead communications engineer
for Grumman on the lunar lander. He used to boggle our minds with stories
of the truly absurd lengths that NASA made them go to have hardware "space
certified."

On Monday, May 6, 2019, Bob kb8tq kb8tq@n1k.org wrote:

--
Homo sum humani a me nihil alienum puto.

Yes:
http://www.excelitas.com/Pages/About/History.aspx

John K1AE Bolton, MA

-----Original Message-----
From: time-nuts [mailto:time-nuts-bounces@lists.febo.com] On Behalf Of jimlux
Sent: Monday, May 06, 2019 9:52 PM
To: time-nuts@lists.febo.com
Subject: Re: [time-nuts] Rubidium Cells for Sale ?!

On 5/6/19 3:54 PM, Bob kb8tq wrote:

Yeah, this one:
Radiation
Hardened to withstand natural and manmade space environments, including
phase- continuous operation through transient radiation

is a pain.

The vibe is high, but not mindbending they don't say whether it's sine
or random. But as a comparison the usual cubesat qualification level is
14grms...

Who was Excelitas originally?  Salem, MA  - is it EG&G?

time-nuts mailing list -- time-nuts@lists.febo.com
To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com
and follow the instructions there.

On 5/6/19 7:04 PM, William H. Fite wrote:

This is changing..

Recognize that for NASA, they're usually building just one (or maybe 2
flight units plus a spare, if you're on a big budget Class A mission
with redundant strings). So they don't think in terms of MIL-HDBK-217
kinds of reliability calculations of statistics.. It's more a matter of
"what could go wrong, and how can we prevent that".

So you wind up with a lot of requirements and tests that may not be
statistically justifiable. They tend to require large design margins
(since you're building just one, the unit test campaign is both
verifying the design AND doing acceptance testing).

For instance, some years ago voltage/frequency stress testing was
popular - run it at a variety of frequencies and voltages, well beyond
the design range, and show that you've got margin.

There's also a "if it doesn't meet the datasheet specs under all test
conditions, it is deemed to have failed" philosophy.  A classic problem
is optocouplers.  You might choose a part that has a current transfer
ratio of 100, and your design needs a CTR of 1.  But the data sheet says
90<CTR<110.  So after radiating it with some dose, the CTR has degraded
to 85.  The part still works just fine (you need a CTR of 1) but the
parts engineer says "nope, that part has failed at the dose, you can't
use it".

A lot of space qualification is paperwork to prove you have
"traceability to sand" for the parts.  Lot numbers, production dates,
etc.  So when the GIDEP (http://www.gidep.org/) comes out for a 2N2222A
(yes I've gotten one), you can go and see if YOUR particular NPN
transistor is covered.

And then there's testing at many levels (not all of which is valuable)...

Incoming inspection of resistors.  Back in the 60s, someone must have
gotten a "out of spec" resistor in a box of 5% resistors - so the
procedure was put in place: Measure each resistor (after assigning a
serial number, and verifying the color stripes, including the stripe
width and colorimetric properties) with a calibrated ohmmeter(with
calibration data recorded), record each measurement, and attach that the
to the build book.

So, today, you get a reel of 1000 resistors all 100 ohms. Someone in
incoming inspection in a clean room at an ESD safe (to 50V) workstation,
pulls each resistor off the tape, takes a picture of it, verifies the
physical size on a coordinate measuring machine, measures the
resistance, logs that information, and carefully places the resistor
into an assigned cell in a waffle pack.  Then, later, someone takes the
resistors out of the waffle pack, puts them back into a tape, after
measuring the resistance and dimensions, so that it can be loaded into
the automated assembly machine.

This is what makes space qualified equipment expensive.

Hi

It was EG&G Frequency Products back when I worked for them (not
in Salem, but still the same division).

They then bought Perkin Elmer and changed the name. Now they seem
to be somebody else ..,.,.

=======

You can go into whatever loops you care to about the way space products
are done. The gotcha is that making sure it’s done right is way cheaper than
sending a tech to Mars to fix this or that. Right now they are saving a ton of
money because the “old” GPS sats (with the EG&G Rb’s in them ) just will not
die. Thus they have waited a decade to send up the replacements ….

Before we start hearing “well, noting ever breaks these days” …. how is the
Galileo system doing for frequency standard reliability ? :)

======

In terms of “I don’t want one” …. well, they are pretty much the best Rb ever
made anywhere / ever. They are as close as you will get to a maser and
not be a maser.

Bob

And it drives SpaceX nuts. Likely the other privates, as well. SpaceX
recovers a faulty part or system, analyzes the problem, resolves it, tests
the revision, and is ready to go. "No no," says NASA. "First we must have a
workgroup to define the problem. Then we must have a workgroup to identify
possible solutions with a subgroup to analyze the resource requirements for
each. Then there is a workgroup to analyze the findings of the previous
workgroups and offer recommendations to senior leadership. Leadership
checks to assure that the distribution of suppliers and contactors to
implement the solution provides sufficient lagniappe to key congressional
districts. The chosen solution is then referred to a feasibility workgroup.
Its findings are sent to a materiel acquisitions workgroup that ultimately
lets bids for the required engineering, parts, and labor. An oversight
workgroup is empanelled to coordinate the fix, overseen by a quality
assurance workgroup. A validation and certification workgroup takes a final
look, 113 concurring agency approvals are solicited, and the fix is
declared ready to go back to space."

On Monday, May 6, 2019, jimlux jimlux@earthlink.net wrote:

--
Homo sum humani a me nihil alienum puto.

In message BFAC22A1-27AE-4B1F-8FDF-EEC87133BB41@n1k.org, Bob kb8tq writes:

Rumours has it that the design is optimized for space use and therefore
not quite as fantastic at sea-level.

--
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, given the price, running it in a thermal-vac chamber would not significantly increase
the charges to your credit card :)

Bob

On 5/7/19 2:16 PM, Bob kb8tq wrote:

But perhaps Poul-Henning was thinking about the gravitational force.
So you could buy two, and drop them alternately down a pair of evacuated
drop towers.

I did notice that the temperature range is quite small for flight
hardware (typical design range might be -10 to +55) - but then, they're
mounted in a fairly large satellite and that's basically putting the
thermal engineering responsibility on the satellite bus engineers.
Holding within 5 degrees nominal is fairly straightforward

it's people wanting to hold milliKelvins that are the ones making trouble.

Hi

Nope, the main issue is that “space benign” (to use the old Mil-HBK-217 term) is indeed pretty
benign. No air pressure change to worry about and a pretty narrow temperature range. Also not
a lot of shock and vibration (once you get there ….)  :)

Bob

On Tue, May 07, 2019 at 11:37:46AM -0400, William H. Fite wrote:

--
Dave Emery N1PRE/AE, die@dieconsulting.com  DIE Consulting, Weston, Mass 02493
"An empty zombie mind with a forlorn barely readable weatherbeaten
'For Rent' sign still vainly flapping outside on the weed encrusted pole - in
celebration of what could have been, but wasn't and is not to be now either."

On Tue, 7 May 2019 11:36:55 -0400
Bob kb8tq kb8tq@n1k.org wrote:

The PHM seem to suffer from an inherent problem in space.
I had the chance to talk to some of the people from Spectratime
last year at EFTF and learned that the US had the same problems
with hydrogen masers in space. They couldn't solve it so they
dropped the idea of using them for GPS. Unfortunately, this knowledge
ended up only as a sidenote somewhere and the Galileo people learned
of it only after they had problems. AFAIK, the root cause of the
problem is still not know, but continuously running the PHM seems
to mitigate it.

The RAFS IIRC had a nice combination of slight design oversight and
too eager testing, where the test procedure made the device unrealiable.
AFAIK this has been fixed quickly and the last couple of launches shouldn't
have any problems.

		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, Neal Stephenson