[time-nuts] Confused about Rubidium oscillators

[Bob Smither]

Do Rb oscillators wear out?  I have found:

"There are no “wear-out” or “use-up” mechanisms in a Datum
Efratom Rubidium oscillator."
  -- Datum - Note About Rubidium Oscillators

and

"Atomic Vapor Oscillators have no wear out mechanism."
  -- FEI - Precison Oscillator Overview, 2007, p19.

But also:

"Unlike a quartz crystal oscillator which has no clearly-defined "wear out"
period and, if well-designed, can actually improve as time goes on, a Rubidium
reference has a definite lifetime associated with its lamp:  As the unit
operates, the Rubidium within the lamp is gradually consumed and eventually, too
little vapor is available for the atomic resonance to be detected and the unit
fails."
  -- http://www.ka7oei.com/10meg_rubidium1.html

and

The page at:
  http://www.oscilent.com/esupport/TechSupport/ReviewPapers/IntroQuartz/vigcomp.htm
also mentions a wear out mechanism.

and

"These OCXOs maintain performance characteristics comparable to Rubidium
oscillators without their high cost and inherent wear out,"
  --
http://www.microwavejournal.com/articles/2301-an-ocxo-with-rubidium-oscillator-performance

Finally I found:

"Problems with rubidium cell wear-out have been solved and manufacturers now
offer essentially unlimited warranties against cell failure."
  --http://www.endruntechnologies.com/frequency-standard-oscillators.htm

so maybe both points of view are correct?

I recall seeing something about rejuvenating Rb oscillators on this list, so I
suspect Clint is correct.

Whose right?  As a time-nut, do you leave your Rb oscillators on 24/7?

Thanks,
-- 
Bob Smither, PhD                                   Circuit Concepts, Inc.
=========================================================================
"Experience hath shewn, that even under the best forms [of government]
those entrusted with power have, in time, and by slow operations,
perverted it into tyranny." --Thomas Jefferson
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Smither at C-C-I.Com  http://www.C-C-I.Com  281-331-2744(office)  -4616(fax)
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