I remember a time when some at PBT referred to the HP5065A as their
precision pressure sensor
Bert Kehren
In a message dated 3/22/2017 10:03:58 A.M. Eastern Daylight Time,
kb8tq@n1k.org writes:
Hi
In this case, the vacuum might work against you. You change the pressure
outside
the package and you get a flex. Flex translates to dimensional changes.
That gives you
a frequency shift. People make absolute pressure sensors this way :) Rb’s
are by no
means the only frequency standard impacted by this effect. Precision OCXO’
s have the
same issue.
If you had enough room inside the package, you could do a “can in a can”
sort of approach.
The outer vacuum sealed can flexes. The inner vacuum sealed can does not
see anything.
You don’t eliminate the sensitivity this way, you do attenuate it quite a
bit with each layer.
The question then becomes - is is worth the increase in size? Since the
pressure sensitivity
is well below many other environmental factors …. probably not.
Bob
On Mar 22, 2017, at 1:04 AM, jimlux jimlux@earthlink.net wrote:
On 3/21/17 4:29 PM, Hal Murray wrote:
However CSAC not subject to barometric effects as Rb units are
Does anybody tried to measure CSAC vs pressure?
The physics package in a CSAC is a vacuum, so it probably won't make
But, as a practical matter, I have a system with a CSAC going through
thermal vacuum testing as I write this. We'll get some test data and we can
compare the frequency against GPS and a OCXO at room temp/pressure, and at
various temps in vacuum.
Remind me in 2 weeks, and I should have the data plotted.
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I remember a time when some at PBT referred to the HP5065A as their
precision pressure sensor
Bert Kehren
In a message dated 3/22/2017 10:03:58 A.M. Eastern Daylight Time,
kb8tq@n1k.org writes:
Hi
In this case, the vacuum might work against you. You change the pressure
outside
the package and you get a flex. Flex translates to dimensional changes.
That gives you
a frequency shift. People make absolute pressure sensors this way :) Rb’s
are by no
means the only frequency standard impacted by this effect. Precision OCXO’
s have the
same issue.
If you had enough room inside the package, you could do a “can in a can”
sort of approach.
The outer vacuum sealed can flexes. The inner vacuum sealed can does not
see anything.
You don’t eliminate the sensitivity this way, you do attenuate it quite a
bit with each layer.
The question then becomes - is is worth the increase in size? Since the
pressure sensitivity
is well below many other environmental factors …. probably not.
Bob
> On Mar 22, 2017, at 1:04 AM, jimlux <jimlux@earthlink.net> wrote:
>
> On 3/21/17 4:29 PM, Hal Murray wrote:
>>
>> scmcgrath@gmail.com said:
>>> However CSAC not subject to barometric effects as Rb units are
>>
>> Does anybody tried to measure CSAC vs pressure?
>>
>>
>>
> The physics package in a CSAC is a vacuum, so it probably won't make
much difference.
>
> But, as a practical matter, I have a system with a CSAC going through
thermal vacuum testing as I write this. We'll get some test data and we can
compare the frequency against GPS and a OCXO at room temp/pressure, and at
various temps in vacuum.
>
> Remind me in 2 weeks, and I should have the data plotted.
>
>
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> time-nuts mailing list -- time-nuts@febo.com
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