Hi friends,
Thanks to so many people who take their time responding to my question:
high lock z0 drift of our Oxford AS-500 magnet with Inova console. Dr.
Chung from Scripts provide an archive from an earlier discussion for a
600MHz, the address is
http://wwitch.unl.edu/ammrl/archives/Nov_Dec-99/0100.html
http://wwitch.unl.edu/ammrl/archives/Nov_Dec-99/0106.html
To summarize the responses I got:
1. For many magnets (the majority responses) from Varian, one has to
reset the lock frequency due to the drifting. The resetting time ranges
from 3 months to a year depending on the drift rate. One usually does
not need to do that in Bruker magnet. The reason might due to different
design in the console rather than the magnet.
2. Most responses indicate that there will be no big problem in terms of
daily operation, although it is an inconvenience. However, probe tuning
and changed values from other shims(i.e. lineshape) may need to be
monitored due to the change of z0 value.
3. Most responses indicate that frequency drop out of filter
bandwidth/amplifier is unlikely to happen before reseal the magnet in
10+ years. A good suggestion is try to see if one can get a free
servicing pump up from Varian/Oxford.
4. Since my quoted magnet drifting rate is <10Hz/hr, there is no solid
base to question Varian. In fact, it is not too bad to have 5~6 Hz/hr
drifting.
Based on the responses, I think I can relax and try to work something
out with Varian/Oxford.
Cheers,
Wei Li
-----------------------------------------
Wei Li, Ph.D
Dept. of Pharmaceutical Sciences
University of Tennessee HSC
847 Monroe, Room 327
Memphis, TN 38163
Phone 901-448-7532 (Office) Fax 901-448-6828 (Office)
Phone 901-527-6784 (H)
Received on Fri Apr 06 2001 - 15:31:53 MST