Hi Ken
I will thrown in this 'free of charge' wisdom, about the comment on the
oscillating Lock vis-a-vis Bruker engineer's comment. To me it looks like
the cause and effect are flipped in this case. Shims going out of whack
can lead to your Lock dancing around and in this regard the Lock functions
as a bellwether about how things are with B0 homogeneity, which is an
expected role played by the apparent Lock level among other things. I
don't readily see how the oscillating lock level can be grouped within the
'causes of the issue' camp.
Albeit in a different system, I have seen this oscillating lock level
when I used to run very low temperature experiments on my older 500 system
with RT probe (ca. -90C or so) and it used to be impossible to shim this in
any meaningful way. Of course, the cause here is the shim stack's
temperature continuously changing for as long as I want to run the
experiment. (I successfully rigged a homemade setup to pump warmed up gas
through the BST collar thereby stabilizing the shim stack temperature and
the problem evaporated).
So, the question to ponder over is if your shim stack temperature is stable
or not in the Prodigy system. There is an automation script 'coiltemp'
that can be run from the Topspin command line, with a time interval
provided as an argument say : 'coiltemp 10' and it will record the shim
coil temperature every 10 seconds and write it to an Ascii file in the
user's home directory. The filename it records it is called 'coiltemp'.
You can investigate it to see what is happening with your shim stack. There
are three columns in the file, with the second being the time stamp and the
third being the shim stack temperature.
Best Regards
Rajan
On Mon, Jan 8, 2024 at 2:32 PM Walt Massefski <wwm_at_mit.edu> wrote:
> Hi Ken,
>
> Following on Jeff’s last point, if you think the problem is
> Prodigy-related, the Configuration page of the Prodigy display shows the
> probe coil temperature (and lots of other things) - you might dial it up to
> see if anything is cycling at about the time scale of your oscillation.
> Best,
> Walt
> -------------------------------
>
> Walter Massefski, Ph.D.
> Director
> Department of Chemistry Instrumentation Facility
> Massachusetts Institute of Technology
> 77 Mass. Ave. Rm: 18-0090
> Cambridge, MA 02139
> T: (617) 253-2016
> wwm_at_mit.edu
>
>
>
--
____________________________________
Rajan K Paranji, Ph.D.NMR Services Manager
*Department of Chemistry**Room 65, Bagley Hall*
University of WashingtonSeattle, WA 98195
phone : 206 685 2581 fax: 206 685 8665email: rajanp_at_uw.edu
____________________________________________________________________
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Received on Mon Jan 08 2024 - 16:43:56 MST