Chris Caudle wrote:
From: "Rick Karlquist" <rich...@karlquist.com>
Is there any evidence that these crystals are actually
baked out at a higher temperature than cold weld
copper packaged ones?
Did you find the second link that Bruce G. provided? At the page labeled
379 (I think actually page 11 of that document), the section "Future
Research for Deep Space Mission Needs" describes the processing. Baking at
over 230 deg. C to drive out impurities, and when doing that and drawing a
vacuum, the copper softens and collapses if you try a standard package.
I don't know if those fox all-quartz packages can maintain high vacuum or
not. I guess I could ask them next time they are trying to get me to buy
some oscillators.
In contrast, Oscilloquartz BVA use coldwelded package with a chimney,
bake it at 250 C and vacuum pump to 10^-8 mbar. They then seal it
through pinchoff. It is fairly well described in the 8601 datasheet.
They even feature a nice photo of the BVA package with measures and all.
Another interesting feature of the BVA design is a reduced sensitivity
to gravity. The 8601 datasheet even contains 360 degrees turn-graphs to
illustrate the sensitivity.
In one of their papers they even had the f^-3, f^-1 and white noise
levels given.
The 8601 runs hotter than the 8600. 4,5 W against 2,5 W if beleiving the
datasheets.
Wish I had a 8607 to run along with them. Ah well.
Should make a rig to get the E1938A running and 10811A and 10811B as well.
Cheers,
Magnus
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