Dear all,
Back a while ago, I posted a question about observing the annoying overflowing problem when we do carbon detection on our inova-500 with vnmr61.c and Solaris 8, after careful comparison, the sensitivity of the carbon signal is also very bad. I received many responses, thank you very much. Several people have seen or are having similar problem and I think it is best to post an update here.
Basically it is not solved, after trying most of the suggestions and working with vendor's tech support people. It is not related to the probe or filters. The overflow persists when all the cables are disconnected from the probe, and/or when the proton decoupling is turned off. Overflowing only disappears when either end of the quarter-wavelength cable disconnected, or the lower end cable on the carbon preamp disconnected, or when setting the receiver gain very low. The vendor's technical support expert said it could be normal due to the aging of the instrument (but it was installed for less than 5 years), and as long as keeping the gain down, the instrument should be fine. The indirect detection works fine without any problem. I don't buy what the tech support person told me, as when we ran carbon before, the gain was always set to 60 without any problem. But we are not ready for another carbon preamplifier or other solutions, so I set this aside and work it up in the future.
Thank you very much for all the suggestions.
Best regards,
Wei Li
Wei Li, Ph.D.
Assistant Professor and Director of NMR Facility
Department of Pharmaceutical Sciences
College of Pharmacy
University of Tennessee Health Science Center
847 Monroe Ave., room 327A
Memphis, TN 38163
901-448-7532 (Phone)
901-448-6828 (FAX)
Received on Wed Nov 09 2005 - 19:55:37 MST