Hello Everyone,
I have been experiencing a problem with low S/N on the X-channel of my
AMX-300. This problem has been ongoing since last October. The S/N ratio
is about 1/4 of the value that it should be for both carbon-13 and
phosphorus-31 (no others checked). Since we have a service contract with MR
Resources, I have been trying to work through them to resolve this problem.
They have sent somewhere in the neighborhood of about 5 BB preamplifiers,
all of which gave similarly inferior results. They also sent out a couple
of R-FT boards for the SE-451 Frequency Unit and a different preamp housing
(triple drawer). None of these exchanges has solved the problem. When I
place a dedicated 13C preamp (provided by MR Resources) in the drawer, I get
a good S/N ratio for 13C, similar to what I used to get with my BB preamp.
MR Resources has not been able to solve this problem and I was hoping that
someone out there might have run in to this situation before. The proton
channel works fine and all 90 degree pulse widths are essentially the same
as they have been since the instrument was installed 91/2 years ago.
If anyone has had this problem in the past and/or can offer a possible
solution to this problem, your help will be greatly appreciated.
Thanks,
Received on Wed Feb 13 2002 - 17:07:40 MST