Dear Keith,
> I'm trying to get the SELINCOR experiment working and have to
> calibrate the shaped pulse on the decoupler channel first. I'm using
> experiment 7.3 from Braun/Kalinowsk/Berger's 150 and More Basic NMR
> Experiments for the calibration. It works to the extent that I can get
> the antiphase doublets but changing power levels for the shaped pulse
> doesn't seem to affect things at all.
>
> I'm wondering if I might be using an incorrectly written the pulse
> program and if anyone has a version for the AMX spectrometer that
> works.
I believe you ran into a hardware problem. The proton transmitter
internally consists of two parts and unfortunately in the case
of AMX spectrometers there is a siginificant internal cross talk
between the two parts. Even if the high power part of the ecoupler
isn't used for your soft pulses, this high power part produces a
significant output, which seems to dominate in your case.
To avoid this behaviour you can connect one or even more
antiparallel diodes to the high power output of the ecoupler.
This reduces the output voltage by a fixed value. This has
nearly no effect for high power pulses but suppresses unwanted
spurious signals, described above.
Hope this helps
Rainer
Received on Thu Apr 19 2001 - 10:16:03 MST