Discussion:
HP cesium beam tube life
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Perry Sandeen via time-nuts
2018-06-20 00:43:44 UTC
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Yo Dudes!
A while back someone asked about the life of a HP Cs tube.
 Fromthe HP 5061B Operators Manual:
 “2.7  The shelf life of the cesium beam tube I twoyears at storage temperatures up to +35 C (+95F) if the ion pump is operated 2 or 3 times a year.  If the ion pump is not operated to maintainthe vacuum within the cesium beam tube, the expected shelf life is reduced.”

 “2.8  Temperature during storage and shipmentshould be limited as follows:

 a.   Maximum temperature: +75 C (167F).  Long term storage: +35 C (95F).

 b.   Minimum temperature: - 40 C  (-40).
 NOTE: 
Whenstoring the HP 5061B for 6 months or longer, set the MODE switch to CS OFF andapply continuous as line power to the instrument.  This enables the ion pump to maintain thevacuum within the cesium beam tube with the cesium beam tube off.”
Bold emphasis by HP
Mysnarky comment about 2.7.   Shelf lifeinfers a tube uninstalled in storage.  OK,how about a detailed procedure with drawings, for taking the tube and temporarilyrunning the ion pump to extend the shelf life?.  Apparently no oneread this comment and thought about its logical implementation.

 

Regards,

 

Perrier

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paul swed
2018-06-20 02:04:12 UTC
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Well one time nut did. Think its John and a ham K5??? call.
He wrote the process up using an external supply.
Thats why I have a 3KV supply on the shelf.
Regards
Paul
WB8TSL

On Tue, Jun 19, 2018 at 8:43 PM, Perry Sandeen via time-nuts <
Post by Perry Sandeen via time-nuts
Yo Dudes!
A while back someone asked about the life of a HP Cs tube.
“2.7 The shelf life of the cesium beam tube I twoyears at storage
temperatures up to +35 C (+95F) if the ion pump is operated 2 or 3 times a
year. If the ion pump is not operated to maintainthe vacuum within the
cesium beam tube, the expected shelf life is reduced.”
a. Maximum temperature: +75 C (167F). Long term storage: +35 C (95F).
b. Minimum temperature: - 40 C (-40).
Whenstoring the HP 5061B for 6 months or longer, set the MODE switch to CS
OFF andapply continuous as line power to the instrument. This enables the
ion pump to maintain thevacuum within the cesium beam tube with the cesium
beam tube off.”
Bold emphasis by HP
Mysnarky comment about 2.7. Shelf lifeinfers a tube uninstalled in
storage. OK,how about a detailed procedure with drawings, for taking the
tube and temporarilyrunning the ion pump to extend the shelf life?.
Apparently no oneread this comment and thought about its logical
implementation.
Regards,
Perrier
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c***@juno.com
2018-06-20 17:54:09 UTC
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The "shelf life" referred to is only related to tube vacuum without
pumping occasionally.

It was derived from an estimate of how badly a worst case tube would
leak.

Most tubes have an almost perfect vacuum seal and this "shelf life" is
indefinite.

Leaving a 5061A/B on and in the Cs-off mode keeps the ion pump on.

The actual life of a continuously working tube is conservatively
estimated by the warranty lengths HP assigned to the various tube styles.

Cheers,

Corby

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