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Z31980_00_03
Installation
• "Asymmetric smileys" in some 1D spectra with high intensity. This can also be seen
as reduction in the level of noise about 200 Hz from the right edge of some 1D and
2D spectra. If this part contains spectral information, simply increase the spectral
width.
* If you obtain reproducible "spurious spikes" in 1H spectra it may be due to an
unfavourable BF1 frequency. The Fourier DDS are "clean" for at least 200ppm
round 300.18 MHz
6.14 Main Differences between Fourier & Avance Systems
• The Lock works at 1 kHz instead of 6 kHz. That means that sidebands are closer
together. Also the lock parameters have different units to BSMS Values.
• Shim Values go from -32768 to 32768. If converting from a AVANCE shim file, you
will need to halve the values to get a good starting point.
• No PID Self Tune for Lock, VTU and Spin Parameters. Since the Fourier is only sold
with one probe, the defaults if operated at 4 bar are usually good enough for all
experiments.
• Different Pulse Programmer Language
• Digitizer Type must be set to “DRMS”
• Aq.mod must be set to qsim
• Fn_Mod must be set to TPPI or QF
• BC-Mod must always be set to OFF
• GPNAM must always be RECT.1
Typical Values for the Fourier are:
P: 0.1 to 0.8 depending on solvent.
Higher values mean more proportional gain.
I: 0.1 to 0.8 depending on solvent.
Higher values mean more integral gain.
Power: -12 to -28 dBm depending on solvent.
Note: The values shown in the BSMS Panel are attenuations
from 0dBm.
Filter: 4 for strong solvents, 1000 for weak solvents. The numbers are
not the Bandwidth in Hz but the number of averages per second.
1000 is equivalent to 1 Hz, 4 is equivalent to 250 Hz.
Field: 0 to 4095. 2048 means no current flowing in H0 Coil.
Ideal value is between 1500 and 2500, to allow for magnet drift.
The BSMS field has the opposite polarity, i.e increasing the value
of the field DAC by 1000 steps will cause a shift left (i.e increase
the frequency) by 20 ppm.
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