I find on my 253 that the ideal extraction voltage (to get good linearity)
shifts higher over time as the filament ages. Try checking your linearity at
70%, 80%, and 90% extraction.
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From: Stable Isotope Geochemistry <[log in to unmask]> On Behalf Of
Sent: July-12-19 3:46 AM
To: [log in to unmask]
Subject: [ISOGEOCHEM] MAT 253 - Linearity
We are trying to get an old MAT 253 up and running again and have problems
with getting the source linear for the range of 3 to 7 V. In the past
there wasn't any problem with an extraction of 60%. Now we have an enormous
drift of around 0,3 permille /Volt CO2, also with increased extraction.
The source is cleaned and std_on_off is very good after 15 minutes.
In the past the MAT was used with a GC/C-unit. Now we run it with a ConFlow
III. I already suspect, that the interface could be the problem and not the
Any hints concerning the right source settings and other causes of this
problem are appreciated!
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