[time-nuts] R&S XSRM Rubidium

Magnus Danielson magnus at rubidium.dyndns.org
Sun Jan 9 09:57:30 UTC 2011

On 09/01/11 03:56, Magnus Danielson wrote:
> Hi!
> My R&S XSRM Rubidium is having problems. It behaves as there is no light
> from the lamp, and I can't see any light from it, but I let it warm up
> again. The manual doesn't give clear indication on how one should
> observe light, but it seems like there is three locations where some
> light might be observed if there where any.
> The lamp assembly do have a 100 MHz resonance going and the assembly do
> get hot. I need to check the temperature thought.
> Spare Rubidium lamps seems to be a bit hard to get by. Having asked R&S
> about it I have not been given any indication of availability. R&S has
> designed the unit such that the lamp can be switched while the rest of
> the unit remains hot. They should have included a small supply of lamps
> too...
> I assume that the light is visible, I seem to recall it and I am just
> too lazy to check the colour right now.
> If anyone has experience in the XSRM or similar (HP5065A for instance)
> beasts, please let me know. It would be greatly apprechiated if
> assistance would let it could go into operational state again.
> The resonator package is certainly not miniatyrized.

Probing around the temperature I think the lamp assembly is running low 
(about 89-90 C, expected 108 +/- 2 C) while the resonator assembly is 
running high (about 94-95 C, expected 68-78 C).

It could be that the lamp temperature is simply to low for any 
meaningful light to emerge. Naturally it looses more temperature in open 
mode right now. Ah well.

Has to try it out.

Luckilly I have a Fluke temperature meter setup laying around.


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