On Fri, 2 Feb 2018 11:02:27 -0800
cdelect@juno.com wrote:

I do not know the HSO-14, but when I asked what the 8607 costs new, I
got ~5000 CHF for the "lowest" grade and over 14k CHF for the highest
grade. Of course this was a couple of years ago. I do not know how
the prices changed in the meantime. Considering that Rakon does not
build a true BVA, but instead puts the electrodes directly on the
resonator, I would expect them to be quite a bit cheaper (because
it doesn't require the couple of µm precision between the resonator
and the holder/elctrodes the BVA has).

		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

Hi

The “BVA” part of the name refers to the slots machined into the crystal blank
to manage the mounting stress on the resonator. Both the “plated on the blank”
and the “electrodes off blank” versions are legit BVA approaches. Indeed the
electrode off the blank version is the more expensive (and higher performing)
of the two.

In addition to price, one probably would want to get a quote of the delivery lead
time. There are some fancy OCXO’s out there with > 1 year delivery cycles.

Bob

Hi,

The slots and thus the remaining bridges seems to have been a relatively
simple stage of the process. Orientation of the blank seems to have been
simple. The shapes for the electrodes seems to have been worse.

Cheers,
Magnus

On 02/03/2018 11:34 PM, Bob kb8tq wrote:

In message 31183984-ed9d-60e1-6528-76dfde5f3f27@rubidium.dyndns.org, Magnus D
anielson writes:

I heard a talk about "microfluidic system production" last year,
those are basically hydraulic systems on micrometer scale, mostly
for medical diagnostic applications.

There was some banter about available tools[1] and some of the ones
mentioned immediately rang the "BVA" bell in my mind.

It sounded to me like there are machines commercially available
today which could spit out very repeatable BVA assemblies in one
single operation.

I have no idea if the result would actually work and be on frequency,
or for that matter, where I can borrow one of those machines, but...

The prices mentioned were not prohibitive in the context, you would
break even well before a thousand units at the prices mentioned.

Poul-Henning

[1] Surprising to me is that modern dentists are highly kitted for
CNC-ing very hard ceramic materials at high precision.

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Hi

Back when the BVA was up for sale, by far the biggest issue was the machining involved
in making those slots. They don’t just have to be slots. They have to be very precise. Etching
will not do the trick. Neither will most machining processes. Electrode shape changes have
been part of resonator production for a lot of years …..

Bob

On 2/3/18 3:31 PM, Poul-Henning Kamp wrote:

with increased use of very high performance DDS and PLLs, the precise
frequency may not be as important as it was when you were limited to
straight up multiplication/mixing synthesis.

I suspect that a "10 MHz +/- 100kHz" might be a higher yield requirement
than 10 MHz +/- 1ppm or +/- 1 ppb.

You could focus more on aging behavior.

But, small "tooth sized" pieces - how big is your crystal.

In message 0f9a9acc-4cdf-780f-e633-6162622641e3@earthlink.net, jimlux writes:

Well, they appearantly make a mouth-full at a time, so that is
covered...

I don't think the dentist machines are precise enough though,
as I understood it, the state-of-the-art stuff has built in
laser-interferrometers etc.

--
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

If you try “normal” machining techniques on a resonator, you are very
likely to create micro cracks in the material. Those are really bad for
aging and a few other issues ….. Much of the normal production flow of the
quartz is designed to keep the processes like sawing far enough away
from the “end product” that more gentle techniques can be used to remove
the (possibly) damaged material.

Since the slots are pretty darn small, there isn’t a lot of room for this and that
to be done when making them. There may well be better ways to do the
work today than back 20 or 30 years ago. It would still take a lot of effort
to validate a process.

Bob

Fluid jet polishing perhaps?

At least on fused quartz and optical glass there is no associated subsurface damage.

Bruce