[time-nuts] R&S XSRM Rubidium

paul swed paulswedb at gmail.com
Tue Jan 11 18:53:28 UTC 2011

Crazy question. Though the small rb references are difficult to disassemble
they can be. I believe I have seen what you describe. Might this technique
be used on those also. I have a flaky end of life old telco reference that I
would open up to try it on. Though no heat gun.
Does the RB really become exhausted or does it plate to the glass like you
Thanks for the thread.

On Tue, Jan 11, 2011 at 1:26 PM, Magnus Danielson <
magnus at rubidium.dyndns.org> wrote:

> Chris,
> On 11/01/11 06:43, Chris Erickson wrote:
>> Would someone mind posting the manual for this? I have a dead one in the
>> closet that needs my attention and I'm not quite sure where to start. The
>> power supply works, but no other signs of life.
> When I get around to scan it I will put it on my web.
> I'd guess that you have the same problem as mine.
> 1) Bring it out of the closet
> 2) Release the lamp-removal tool (its located to the left side just behind
> the front of the XSRM module, there is a pair of holes lower down for screws
> holding the removal tool, but loosing one of them and you can bring the tool
> up)
> 3) then bring into the backside of the XSRM module and unscrew the lamp
> anti-clockwise
> 4) Look into the lamp. If you see the Rubidium splittered around in the
> bottom, possibly have a dark shade on the glas... then you might consider
> the next steps...
> 5) Put the lamp and lamp holder upside down in some form of clamp
> 6) Heat the lamp using a normal heat gun, heat it up properly. If you have
> a dark colouration it will release itself as the rubidium evaporates. Keep
> warming for a few seconds more and then let it cool down.
> 7) When it has cooled down, look into the lamp and if you still have a lot
> of splittered rubidium in the bottom, redo the process. It took me two times
> to get the hagn of it... one way in the wrong orientation. When you are done
> the rubidium should be located as a single droplet in the middle all the way
> back in the lamp assembly.
> 8) Reinsert the rubidium lamp, screw it in clockwise.
> 9) Power the XSRM up and let it zimmer for 30 min or so... let the
> amplitude rise (turn the monitor knob to "CHECK"). If it does not go up
> there, let me know.
> 10) Using a screw-driver slowly turn the trimmer of the OCXO assembly (Y4)
> and see how the Control Voltage reacts slowly as a response. Then you know
> that the loop has closed. Then in small steps bring the control voltage into
> the middle of the response.
> 11) Let it sit there and stabilize before fine-tuning the C-field on the
> multi-turn knob on the front.
> I'll scan the manual eventually, but the above is essentially what I did to
> revitilize mine with that same fault description. If you need any part of it
> let me know. I'll try to help you getting it up and running again.
> Cheers,
> Magnus
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