Ok, I've got one here that's making my head spin a little. I've summed it up
as succinctly as I can for Bruker but I wanted to post it here in case someone
had seen something like this before. Fortunately not urgent, but can't begin
to explain what I just saw on my instrument.
Hardware: Bruker Avance NEO 400 Nanobay, Probe: QNP 400sb F/P/C-H-D-05
Symptom: Operator (me) was watching the 1H turning dip with 'wobb' to check
accuracy of manual tuning. Noticed that VT was switched off, so they switched
it back on in topspin. The moment VT (BCU I) was switched to ON, wobb curve
was observed to move very rapidly out of range of the wobb sweep window. VT
was switched off and trunk line disconnected from the probe. After much hunting,
wobb curve was discovered to be outside the range of tuning rod. Tuning dip
could be observed just beginning to build in just as the hard stop at the end
of the tuning range was reached. Curve responded to both tune and match rods
but no combination of the two could bring into the range, only move it further
away. VT trunk line was re-attached, but VT was *not* switched on. Tuning
dip began to move by itself , slowly into the range and settled somewhere in
the middle. Probe could now be manually tuned. No effect was seen on the X-nucleus,
no effect was seen on the lock signal, only the 1H channel.
Any ideas would be greatly appreciated.
Best,
David O.
-------
David Onofrei, PhD
NMR Facility Manager
Chemistry Department
San Diego State University
work: chem-nmr_at_sdsu.edu
personal: donofrei2_at_sdsu.edu
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Received on Tue Nov 26 2024 - 18:16:12 MST