Dear BUMs,
A couple months ago I posted a query about a phase instability problem on
our DRX-600. This caused us enough grief that I thought you should all be
aware of the solution.
We checked temperature control of the probes and of the room housing the
spectrometer, tested various probes and the HPPR, and swapped out the
Shomandl frequency synthesizer, the proton amplifiers, and many of the
boards in the CCU and AQR (some of them multiple times), all without fixing
the problem.
The problem was solved by taking the spectrometer frequency, which had
drifted down over 4 years to 599.86 MHz, back up to 600.3 MHz (by bumping
the field up). Apparently Bruker has noticed that instruments with
Shomandls which drift down to base frequencies under 600 MHz have unstable
phase. So we had the field bumped back over 600, and presto the phase is
stable again.
Jeff de Ropp
NMR Facility
UC Davis
One Shields Avenue
Davis CA 95616
jsderopp@ucdavis.edu
530-752-7677 office
530-752-6480 Lab
530-752-5682 Lab
530-752-3516 Fax
NMR Facility Web site URL is:
http://www.nmr.ucdavis.edu/
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