To all,
I wish to thank everyone for their advice and input. It turned out to be a
problem in the 12 bit DAC board which affected the Y shim. David Redwine at
DOW had the winning suggestion. Working with Ben Hamilton we checked the
digitizer board, main power supply, shim power supply, roughly in this order
and everything was as it should be. During this time everyone suggestions
were coming in, which reassured us we were on the right diagnostic course.
David's suggestion narrowed it to the shims which made the problem short
work after that.
David's suggestion:
"Chuck,
I'm guessing the problem goes away when you don't spin, although the
lineshape is probably pretty bad.
I think you have one or more of the non-spin shims very wrong. The
chirps you hear are the spinning sideband modulations.
Thanks,
David Redwine
The Dow Chemical Company"
Chuck
Charles L. Anderson, Ph.D.
Manager NMR Facilities Office: 713-743-2728
Department of Chemistry Fax: 713-743-2728
302 Fleming Pager:713-608-7669
University of Houston Web:nmr-central.chem.uh.edu
Houston, TX 77204-5003
"Anything one man can imagine others can make true"
Jules Verne
Received on Thu May 11 2006 - 14:05:14 MST