[time-nuts] Symmetricom XPRO rubidium

[Bob kb8tq]

Hi

The Rb may or may not have moved onto the walls. The lamp (as designed) may or
may not have a well……

Bob

> On Sep 28, 2020, at 11:35 AM, David C. Partridge <david.partridge at perdrix.co.uk> wrote:
> 
> What about using a the hot-air gun technique to migrate the Rb from the walls of the lamp back to the well?
> 
> David
> 
> -----Original Message-----
> From: time-nuts [mailto:time-nuts-bounces at lists.febo.com] On Behalf Of Bob kb8tq
> Sent: 28 September 2020 14:23
> To: Discussion of precise time and frequency measurement
> Subject: Re: [time-nuts] Symmetricom XPRO rubidium
> 
> Hi
> 
>> On Sep 27, 2020, at 10:19 PM, Stewart Cobb <stewart.cobb at gmail.com> wrote:
>> 
>> I have a Symmetricom* XPRO rubidium which appears to be reaching its end of
>> life. The very sparse manual says that it sets a "service" flag when the
>> lamp voltage reaches 600 mV. When I got it, that parameter was at about
>> 540. Several months of continuous runtime later, it's down to about 510.  I
>> assume this is a measure of light emitted by the lamp, but its label is
>> "lamp voltage".
>> 
>> I don't want to lose this Rb, because it seems to be the most stable
>> reference in my lab (about 2x more stable with temperature than a PRS10, by
>> eyeball).
>> 
>> Questions for the hive mind:
>> 
>> (1) Why and how is the lamp voltage falling?  What's the wear-out
>> mechanism?
> 
> It’s looking at the photo detector on the physics package. The amount of
> light getting to the photo detector is “getting low”. Once it gets low enough,
> the SNR degrades. At some point that gets bad enough for the device to 
> loose lock
> 
> 
>> 
>> (2) Is there any hope of repair? Will the heat gun trick for the LPRO work
>> on the XPRO? Could I replace the XPRO lamp bulb with one from a young LPRO?
> 
> The devices are “aligned” to match up with the bulb. The various tweaks to get that
> done are never documented on the Telecom Rb’s. You might get lucky, you might 
> not.
> 
> If you have a working LPRO, there’s no real reason to expect the XPRO to work 
> any better than the LPRO ( at least not after surgery ….). 
> 
>> 
>> (3) Has anyone ever done surgery on an XPRO? Any hints or tips?
>> 
>> (4) Does anyone know anything more about the XPRO? I have data sheets
>> 900-00542-000B and -000F, and manuals 098-00058-000 rev A and rev B. The
>> manuals are just barely sufficient to get the thing running. The device
>> itself displays parameters on its serial interface which appear to be
>> adjustable but which are not described in the manual.
> 
> Sparse manuals are pretty much the way things are done these days. That’s not
> just an issue on Rb’s …
> 
> Best approach is to start shopping …..
> 
> 
> Bob
> 
> 
>> 
>> Thanks in advance for any help.
>> 
>> *Symmetricom has been acquired at least twice since this device was built.
>> But the device label says Symmetricom, and the manual says Symmetricom, so
>> I'll stick with that name for now.
>> 
>> Cheers!
>> --Stu
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> 
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