Michael Baker wrote:

I don't have the exact translation handy, but I ran across something
indicating that BVA was an acronym in French for something like
"improved aging rate".

John

A googlized translation is:

Improved Housing for Aging

-Chuck Harris

John Franke wrote:

Try:

Boîtier à Vieillissement Amélioré

John WA4WDL

----- Original Message -----
From: "John Ackermann N8UR" jra@febo.com
To: "Discussion of precise time and frequency measurement"
time-nuts@febo.com
Sent: Friday, December 07, 2007 11:20 AM
Subject: Re: [time-nuts] Super stable BVA Quartz resonators... BVA??

Reminds me of the "SC" cut crystal.
It either means "Stress Compensated" or "Santa Clara",
where it was discovered :-)

The BVA has been around for a long time and you
would think that if there was really something to
it, everybody would be making them.  Of course, they
are very difficult to make.

Rick Karlquist N6RK

John Ackermann N8UR wrote:

That would be pretty close, for once (referring to google translations :-)

Here is the translation from Oscilloquartz themselves:

"French expression meaning "Enclosure with Improved Ageing". The OSA BVA
crystal oscillators employ special techniques to achieve stability
performance, unmatched by any other crystal device, i.e. typically 1 x
10-11/day."

Didier KO4BB

I am not aware of other crystal oscillators with better performance, so
either I am missing something (the more likely explanation) or there is
something to it.

Maybe the cut is simply a smoke screen and the outstanding performance is
actually due to other process detail(s) not disclosed?

Or maybe their oscillators are not that good, they just blow smoke really
well.

Didier KO4BB

Having low aging is nice, but the real problem is
frequency jumps.  Do we know that they are the best
in that respect?  If a crystal can jump 1E-10, then
that represents 10 days of aging all at once.

Rick Karlquist, N6RK

Didier Juges wrote:

From: "Didier Juges" didier@cox.net
Subject: Re: [time-nuts] Super stable BVA Quartz resonators... BVA??
Date: Fri, 7 Dec 2007 17:17:59 -0600
Message-ID: 06dc01c83927$68d90520$6501a8c0@didierhp

Let's recall that the BVA isn't the same as a cut, but rather an approach to
handle and mount the cut crystal. The BVA exists in both AT and SC cuts.

The analysis of Rick et.al. for the E1938 was pointing in another improvement.

Also, there are many ways to cut a crystal. :)

Smokescreen or not, Oscilloquartz clearly beleive in the BVA methodology and
they seems to have customers for them too.

Is the E1938 commercially available? If not, is there a followup?

Do we really need BVAs or similars for most new designs, considering the price,
size and availability of modern telecom rubidiums?

Well, that would be stupid, since it is easy enought to measure and verify.

Cheers,
Magnus

BVA is a French acronym, it means
Besson Vieillissement Amelioré
Reymond Besson is the scientist who invented it, here in Besancon,
a friend of mine, officially retired, yet still at work.
"Vieillissement" means aging,
"Amelioré" means improved.

Somebody says that it also means "Besson vieux âne", if you
know French, and French culture because this is not the kind
of thing you can translate without killing the meaning.

On 7 Dec 2007, at 17:15 , Michael Baker wrote:

Enrico Rubiola
professor of electronics

web: http://rubiola.org
e-mail: rubiola@femto-st.fr

FEMTO-ST Institute
32 av. de l'Observatoire
25044 Besancon, FRANCE
voice: +33(0)381.853940 (E.Rubiola)
voice: +33(0)381.853999 (switchboard)
fax: +33(0)381.853998

Didier Juges wrote:

There's quite a bit of guff on the "Oscilloquartz" website - especially
if you find your way to the OXCO 8607-B datasheet (pdf).

I'm not qualified to weigh this all up, but they point out a double oven
and an "electrodeless, SC-cut, 3rd overtone crystal, decoupled from its
mounting structure by four rigid bridges". And they go on to list the
consquent benefits.

They've made over 10,000 of them. Anyone know what they're charging...?

Yours,

-Brian Styles

This is another version,

Enrico

Enrico Rubiola
professor of electronics

web: http://rubiola.org
e-mail: rubiola@femto-st.fr

FEMTO-ST Institute
32 av. de l'Observatoire
25044 Besancon, FRANCE
voice: +33(0)381.853940 (E.Rubiola)
voice: +33(0)381.853999 (switchboard)
fax: +33(0)381.853998

Brian Styles said the following on 12/07/2007 07:15 PM:

[ . . . ]

Very rough numbers, but the standard 8607 is about US$4K.

The option -008, which has 8x10e-14 ADEV from 2 to 30 seconds (and phase
noise about -130dBc/Hz at 1 Hz offset) is about $14K. I'm told the yield
of those is about a dozen per year, and the lead time to get one is
around six months.

John

I looked at the HP 10811 specification and I do not see Frequency Jumps as a
specified parameter.

I know what it is, I have read the (very interesting) papers and postings on
this group about it and I understand it is one of the more difficult to
avoid and hardest to predict cause of error in crystal oscillators. Yet, it
does not seem to be adequately covered in specifications.

Is it covered in other spec requirements such as phase noise or short term
stability? But since these also encompass other causes, how can I tell which
is which? If phase noise or short term stability encompasses frequency
jumps, how can I estimate the size of frequency jumps from those
specifications?

Didier

John Ackermann N8UR wrote:

Hmm, not quite long enough to save up, then!

Changing the subject slightly, does anyone know the Thomson-CSF
PMT P5-1E ?

It seems to offer a total stability of 5x10e-11 over a day and 1x10e-8
over 12 months. The latter figure isn't very far behind the best 8607.

I ask because I've had one of these Thomson trinkets kicking around for
a while (washed up from an abandoned project) and thought of building a
clock round it. My own obsession is with long-term accuracy rather than
the immediate spectrum. It has to beat the Synchronomes...

If anyone's played with a PMT P5-1E, I'd be most interested to hear.

Regards,

-Brian Styles

The 10811's specs are not in the same class with the
BVA in the first place.  At the 10811 spec level,
frequency jumps aren't that significant compared to
other frequency fluctuations, so they don't need to
be specified separately.  Phase noise and short term
stability are easily distinguished from frequency
jumps.

Didier Juges wrote:

Coincidentally, I just learned today that the
E1983A is still being made by an OEM called
Scotts Valley Magnetics.

Rick Karlquist N6RK

Magnus Danielson wrote:

From: "Richard (Rick) Karlquist" richard@karlquist.com
Subject: Re: [time-nuts] Super stable BVA Quartz resonators... BVA??
Date: Fri, 07 Dec 2007 17:28:15 -0800
Message-ID: 4759F32F.8040501@karlquist.com

Rick,

Oh, if there would manifest itself a chance to get hold of a few, I hope I can
get a notice. Their products page blew up in my browser, but here they are:
http://www.svmagnetics.com/

Cheers,
Magnus

Same thing here, I checked with Firefox and IE, and the problem clearly is
at their end... Maybe Monday?

Didier

Same for me with both browsers.

Daun

-----Original Message-----
From: time-nuts-bounces@febo.com [mailto:time-nuts-bounces@febo.com] On Behalf
Of Didier Juges
Sent: Friday, December 07, 2007 9:02 PM
To: 'Discussion of precise time and frequency measurement'
Subject: Re: [time-nuts] Super stable BVA Quartz resonators... BVA??

Same thing here, I checked with Firefox and IE, and the problem clearly is
at their end... Maybe Monday?

Didier

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