[time-nuts] Testing the Datum LPRO Rb oscillator

Chuck Harris cfharris at erols.com
Wed Jun 17 19:29:43 EDT 2015

Generally, rubidiums do quite well when left powered down.  They
don't use the extremely hard vacuums characteristic of cesium

Other than the usual electronic component failures, the only thing
that usually happens to cause a rubidium to stop working is the
lamp gets blackened by rubidium condensing out on the glass in a
the beam path.  This causes the signal strength to drop to a point
where the servo can no longer lock.

The usual cure is to heat the bulb carefully until the rubidium is
once again all vaporized, and let it cool.... I use a hot air
gun to supply the heat... Once the bulb is cleared, you are good to
go for another "lifetime".

-Chuck Harris

Sean Gallagher wrote:
> Good afternoon everyone,
> So I have a bunch of Datum and Efratom LPRO Rb oscillators. I know that one of them
> is bad and I already swapped it out. I was getting really long lock times (if lock at
> all happened) and read that was an indicator.
> These things were all made from like 1999-2001 or so and from what I understand have
> about a 15 year lifespan. However a former colleague told me today that this
> limitation is really only if they are powered on. Is this true? If so then some of
> these units apparently were only hooked up for a couple years and then the servers
> they were in were taken offline and they may still have 10+ years of service right?
> I was really wondering if someone could point me in the right direction (or towards a
> tutorial) on how I can test these and see if they are still okay? I don't have a lot
> of engineering experience but I do have access to a multi-meter and an oscilloscope
> and a decent amount of luck when it comes to troubleshooting.
> Respectfully,
> Sean Gallagher
> Malware Analyst
> 571-340-3475
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