We have had problems with users of our Varian Unity-300 who lock and shim,
getting a nice high lock signal, and then start an experiment with "go" and
see the lock plummet. Sometimes this happen even within the lock and shim
menu, when switching from "lock" to "shim" and back. The problem seems to
be due to changing values of lock power and lock gain, and possibly lock
phase, rather than any change in shims.
In the process of searching for the poltergeist, I looked at the "setup"
macro in the maclib and wondered if this is executed when you enter "su" or
"go", or is it executed only when you select "Main Menu" and "Setup" with
the Menu Buttons. Then I got the idea that we could write a "Bruker-like"
macro, similar to the "edlock" feature in XWinNMR, which would load
appropriate values of lock power, Z0, lock gain and lock phase for a given
solvent. The problem is that a Z0 value, being essentially a shim, is not
used until you enter "su", which then sets a lot of other things I don't
want changed.
Could someone explain this to me? Is such a lock solvent macro possible
in VNMR?
Thanks,
Neil
Neil E. Jacobsen, Ph.D.
NMR Facility Manager
Department of Chemistry
119 Old Chemistry
1306 E. University
University of Arizona
Tucson, AZ 85721
520-621-8146
FAX 520-621-8407
Received on Tue Oct 31 2000 - 13:26:23 MST