Varian UNITY INOVA NMR, Hardware Installation, Page: 24 / 65

3.2 Testing the CP/MAS Solids System
01-999044-00 C0501 UNITY INOVA Solids Hardware Installation
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d. Set the decoupler to OFF by entering
dm='nnn' tpwr=63 tpwrf=4095
go
; then measure the power and droop of observe pulse amplifier. It should
meet the following values:
• Minimum power: 300 W, 220 Vpp, +54 dBm (6.3 Vpp, when
measured through a 30-dB attenuator).
• Maximum droop: 2% over 10 ms.
e. Enter aa to stop the acquisition and then reattach the observe cable to the
probe.
2. Check the AMT decoupler amplifier (channel A) according to the following steps.
The maximum drive to the AMT should not 2 dBm.
a. Disconnect the input to Channel A of the AMT amplifier from the ATTN/SW
board and then connect OUT 1 to a power meter.
b. Set
level2=63 level2f=4095 nt=1e6 dm='nny' sw=1e5
np=128 d1=0.1
c. Enter go and add sufficient in-line attenuation at the input of the AMT
amplifier so that the peak power does not exceed 2 mW (+3 dBm).
d. Enter
aa
to stop the acquisition,
dm='n' su
to reset the power, and then
reconnect the AMT amplifier.
Adjusting Decoupler Field Strength
1. Fill a rotor with dioxane (00-957734-01) and cap it with a Torlon end cap (brown).
Note that any other type of end cap will dissolve in the dioxane.
WARNING:
The 1,4-dioxane sample (00-957734-01) is a cancer suspect agent
containing flammable liquid oxidizers. See the enclosed MSDS for
additional information and handling precautions.
2. Spin the sample slowly (200–300 Hz).
3. Enter
rtp('/vnmr/tests/hmb') seqlib='xpolar'
. Use XPOLAR
with
xpol='n'
.
CAUTION:
High spinning speeds can cause the rotor to shatter, creating a
potential physical hazard to the operator. Never spin 7-mm PSZ
(zirconia) rotors (white or off-white in color) above 7.2 kHz or silicon
nitride rotors (gray) above 9.5 kHz.
Decoupler power greater than 2 W will damage a switchable probe. The
maximum value for
dpwr on a 200, 300, or 400 MHz system with a
linear amplifier on the decoupler channel has been set to 49, which
corresponds to approximately 2 W of power. For this reason, do not
use or alter
dpwr
for solids operation. Use the XPOLAR pulse
sequence rather than S2PUL.
Follow all pulse duration, pulse power and duty cycle warnings if given
for a particular probe. Generally, pulse durations can be increased
with a proportional decrease in pulse power.
4. Tune the probe according to the instructions in the manual NMR Probes Installation.
Tune the decoupler channel before the observe channel and with a high-pass filter in
place for a return ratio of 50 dB or better.
5. Check that
dm=nny
,
level2=63
, and
level2f=4095
.