[time-nuts] Confused about Rubidium oscillators

[Bob Camp]

Hi

The FE 5680's appear to have the more modern miniature tubes in them. 

Bob

On Nov 14, 2012, at 7:39 PM, Dale J. Robertson <dale at nap-us.com> wrote:

> Bob,
> Which category do the FE-5680A's fall into?
> Dale
> NV8U
> 
> 
> -----Original Message----- From: Bob Camp
> Sent: Wednesday, November 14, 2012 6:28 PM
> To: Discussion of precise time and frequency measurement
> Subject: Re: [time-nuts] Confused about Rubidium oscillators
> 
> Hi
> 
> There are several different basic Rb cell designs. The old "large cell" designs had relatively little trouble with glass / metal interaction. The early small cell designs tended to turn the bulbs black over time. Newer small cell designs seem to have gotten past that problem.
> 
> Bob
> 
> On Nov 14, 2012, at 5:46 PM, Brian Kirby <bryan-Kerby at att.net> wrote:
> 
>> I believe Corby came up with the bulb "rejuvenation".
>> 
>> If you tried to get a new bulb for a FRK, they wanted $400 in the late 1990s for them.
>> 
>> Several rubidium's are plentiful and cheap, it may be easier to buy one from the auction site.
>> 
>> I have a HP5065A, I run it when I need it, and when not in use, I power it up about every 3 months for a couple of days.  On the HP unit, there is a flooding/pooling problem if the unit is not used.
>> 
>> 
>> On 11/14/2012 10:56 AM, Bob Smither wrote:
>>> 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,
>>> 
>>> 
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