Varian UNITY INOVA NMR, Hardware Installation, Page: 50 / 65

6.2 Testing RF Transmitter Performance
01-999044-00 C0501 UNITY INOVA Solids Hardware Installation
49
2. Set the following parameters:
level2=63 level2f=4095 nt=1e6
dm='nny' sw=1e5 np=128 d1=0.1
3. Enter
go
and add sufficient in-line attenuators so that the peak power does not
exceed 2 mW (+3 dBm).
4. Enter
aa
to stop the acquisition and then reconnect the AMT amplifier.
5. At the input to the high-power decoupler amplifier, calibrate power as a function of
level2
when
level2f=4095
. The maximum should be at least 44 dBm (25 W).
6. Enter
aa
to stop acquisition.
To Test the High-Power Decoupler Amplifier
CAUTION:
For CP/MAS, the maximum decoupler power at the probe should be no
more than 100 W. If this is exceeded, damage to the CP/MAS probe
could occur.
Perform this calibration as follows.
1. Connect a 30-dB, 500-W attenuator to the DEC port on the magnet leg, replacing the
probe. Connect the other end of the attenuator to a scope or spectrum analyzer.
2. Set level2=63 level2f=4095 nt=1e6 xpol='n' and enter the go
command.
3. Measure the output level in watts.
4. Decrease the value of level2 until this output is no more than 100 W. Note that
you must enter aa level2=# go , where # is a new value for level2 , each time
you change the value of level2 .
5. When the
level2
value is determined, halt the acquisition and write down the
value so you can refer to it later.
6. Enter aa and return the system to normal configuration.
Note: Whenever
level1=63
or
level2=63
is used in the next few pages, use the
value determined step 4 above instead of 63.
Adjusting Decoupler Field Strength
1. Use the dioxane sample (00-957734-01) spinning at 200 to 300 Hz.
WARNING:
The 1, 4-dioxane sample (00-957734-01) is a cancer suspect agent with
flammable liquid oxidizers. See the enclosed MSDS for additional
information and handling precautions.
2. Enter
rtp('/vnmr/stdpar/C13') su
to select the
13
C observe parameters.
3. Set HI BAND to LO POWER.
4. Tune the decoupler channel of the probe (refer to the NMR Probes Installation
manual)
5. Check limits of
dpwr
. Enter
dpwr=63
. Check for the value of
dpwr
. If
dpwr=49
appears, the upper limit on the
dpwr
parameter can be changed.
6. Change the following parameters:
at=0.10 d1=30 dm='nny' dpwr=63
. Set
pw
and
tpwr
to the 90° value. Set up a
dof
array by entering
dof=–2e4,2e4
.