Concur with Mike. This does sound like a failed capacitor in the tune
circuit. Even if the B0 field has shifted, until the base frequency is
manually changed in the software, the RF side of things should appear
exactly as they were when the system was installed. The BSMS DAC unit
scales approx. 7 Hz or so per point (for the 1H frequency) and the +/-
10000 width would mean that a complete drift outside the window would be
(+/-) 70 kHz at the max. To get outside the ~ 2 MHz bandwidth of the probe
will take decades, if not eons with your magnet !
It's the RF side that is mostly causing this problem, imho.
Best of Luck.
Raj
On Tue, Jul 25, 2023 at 8:59 AM Michael Groves <m.groves_at_utah.edu> wrote:
> Hi all,
>
>
>
> I would contend that even if the magnet frequency has shifted, it
> shouldn't change the tuning range of the probe. It could keep the system
> from locking if it got too far out, but not change the tuning. Generally
> Bruker probes are configured to have a tuning range of +/- a few MHz from
> the base frequency. Changing the spectrometer frequency by 80 kHz should
> have really no effect on your ability to tune the probe. Assuming it's a
> 5mm probe.
>
>
>
> Have you tried tuning the probe manually with the atmm command? If you do
> so, I would expect you can find which tuning adjustment is at its limit.
> Also, do you have a spectrum analyzer or something similar you could use to
> look at the tuning dip instead of the spectrometer? You could start atmm
> and look at the tuning dip on the spectrum analyzer to make sure that the
> spectrometer is functioning properly—you can adjust tuning and matching
> with the atmm interface and watch the dip on the spectrum analyzer. If you
> can tune it on the analyzer but not on the spectrometer, you might have a
> spectrometer issue. If you can’t tune it on either, then it's a probe
> issue.
>
>
>
> My suspicion would be a failed component in the probe, and it probably
> needs to go back for repair. I would hope it was a failed solder joint or
> a bad chip capacitor so it would be a simple repair.
>
>
>
> Cheers,
>
> Mike
>
>
>
--
____________________________________
Rajan K Paranji, Ph.D.NMR Facility 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 Tue Jul 25 2023 - 09:47:35 MST