5.4 Variable Temperature Operation with Solids
01-999162-00 C0402
VNMR 6.1C User Guide: Solid-State NMR
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The configuration parameters can be saved to a file on the PC (e.g.,
gain.set
). Upon
initial startup, the parameters in this file are loaded in order to set the configuration. Be sure
to make copies of the configuration parameters file (
gain.set
), or write down the current
settings if you wish to experiment with changing the rotor control configuration.
Additional Operation Note
The PC computer has been set up such that a monitor and keyboard is not required in order
to pass the POST (Power On Self Diagnostics) test, which occurs before the operating
system is loaded from disk. These options are set into the CMOS BIOS setup at the factory.
If the CMOS fails for some reason, the BIOS setup will have to be reconfigured.
The most likely cause for CMOS failure is drainage on the battery that powers the CMOS
when the computer is off. This battery is continuously recharged while the computer is on,
so even if the rotor speed controller is not in use, it is wise to keep the computer powered up.
If the computer does need to be turned off, do not leave it off for extended periods of time
(weeks or months). If the CMOS does lose its memory settings, a video card, PC monitor,
and keyboard will have to be attached so that the CMOS set up program (not part of DOS)
can be run.
5.4 Variable Temperature Operation with Solids
This section provides general instructions on the solids variable temperature (VT)
accessory. The accessory installation manual for the system provides more detailed
instructions on solids VT.
Varian Solids VT System
The Varian solids variable temperature accessory (Part No. 00-958994-00) can be added to
a Varian VT CP/MAS probe for VT operation. When this accessory is added, connection
of the gas supplies to the probe is altered in the following ways.
• Body nitrogen is needed whenever the probe is in operation. The connection of the VT
gas supply is described in the VT installation manual.
• The VT controller is connected to a booster power supply and the booster power supply
is connected to the probe. This is accomplished with the solids VT cable as described
in the VT installation manual.
• The liquids upper barrel is pushed down so it touches the top of the probe. This,
together with the Varian bore vent assembly, serves as the exhaust stack.
• VT operation requires the use of Torlon end caps.
G3
0
G4
0
G5
0.5 to 1, with a loop delay of 500 to 700 ms and
an increment clamp of 5000
Gain Setting
Typical Ranges