[time-nuts] So what’s inside that Cs Beam Tube anyway?
kb8tq at n1k.org
Tue Nov 1 07:29:33 EDT 2016
Quite literally 10’s of millions of dollars (back in the good old days) was
put into the idea of a rebuildable Cs tube or rebuilding ones that already
exist. The result was more people in the tube business for a while. They
never did come up with a rebuildable tube or a salvage process. Since the
“prize” was a few hundred million (US government refurbishments over
years and years) if it worked, economics was not the issue.
> On Nov 1, 2016, at 6:51 AM, Attila Kinali <attila at kinali.ch> wrote:
> On Mon, 31 Oct 2016 14:50:51 -0700
> ed breya <eb at telight.com> wrote:
>> It's a shame that they're not built in such a way that just the wear-out
>> parts could be replaced, and not wasting all the rest of the design and
>> craftsmanship that's probably just fine.
> Because it's not that easy. We are talking about a high vacuum system
> here. While you can get a vacuum tube working with a simple rotary
> pump. You can even have something like an ion pump to make the vacuum
> a bit cleaner and make it perform better. But this will not work with
> the level of vacuum you need for a Cs standard. A small finger print
> left somewhere on something, will outgas for many months and make
> the whole system perform an order of magnitude or two worse than speced.
> Yes, Cs beam standards are not as finicky as the modern Cs fountains
> or even worse the optical clocks, but they are still very sensitive.
> It would be possible to make the tube such that you could change the
> "consumables". But it would still take a skilled technician in a clean
> lab with special equipment to do the maintenance. But I am not sure
> whether it would be that much cheaper than a new tube. And you always
> have the risk that something goes wrong and you have the scrap the
> tube for good.
> Attila Kinali
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> use without that foundation.
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