[MSA-Talk] Old Phillips XRD generator

[Henry Barwood]

I recently repaired an old XRG 2000 XRD generator made by Phillips. When
I turned on the HV, I got a quite high Ma on start up. I turned down the
H-M-L control to L and the Ma dropped momentarily to 5Ma and then ramped
back up to around 30-40Ma (at 10KV). This apparently blew out the
filament and the Ma dropped to 0. The tube was old, so I have no idea
if it was gassy and just failed, or if there is some other fault in the
Ma stabilizer. Filament voltage was 7V.

Is there anyone on the list who may have experienced something like this
and can advise me what to do? I have one spare tube, and if blows, I'm
dead in the water. Thanks.

--
Henry Barwood
Professor, Earth Science
Department of Chemistry and Physics
Troy University
Troy, Alabama 36082


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[Rex Couture]

On 9/6/2013 4:42 PM, Henry Barwood wrote:
> I recently repaired an old XRG 2000 XRD generator made by Phillips.
> When I turned on the HV, I got a quite high Ma on start up. I turned
> down the H-M-L control to L and the Ma dropped momentarily to 5Ma and
> then ramped back up to around 30-40Ma (at 10KV). This apparently blew
> out the filament and the Ma dropped to 0. The tube was old, so I have
> no idea if it was gassy and just failed, or if there is some other
> fault in the Ma stabilizer. Filament voltage was 7V.

That sounds like bad news. I don't have any experience with your
diffractometer, but I did have gassy tubes with Siemens fluorescence
tubes and Rigaku diffraction tubes. (I had at least two of each.) As
far as I can remember, each of these tubes still had an intact
filament. I suppose that's because the excess current passed through
gas, not through the filament. I did see someone blow a filament by
turning up the current before the voltage, however (I don't know the
manufacturer).

--

Rex Couture, Ph. D.
Dept. of Earth and Planetary Sciences
Campus Box 1169
Washington University in St. Louis
1 Brookings Dr.
St. Louis MO 63130

Voice: (314) 935-4194
Fax: (314) 935-7361
r...@levee.wustl.edu