[time-nuts] Confused about Rubidium oscillators

Dale J. Robertson dale at nap-us.com
Thu Nov 15 00:39:52 UTC 2012


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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