AMX-300 V.T. UNIT

For general VT operating instructions, refer to the VT Operation manual.

Below are the specific differences between this unit and the ones used on the other Bruker spectrometers.

The vt unit on the AMX-300 is quite different from the units used on the other spectrometers. The unit is truly computer controlled. The temperature can be set by software. A list of temperatures can be set up as well (although we have not yet tried this).

The VT is controlled by more parameters than just the temperature. There are several regulation parameters which may change for a given temperature range.
Since the regulation parameters are a bit difficult to understand, a collection of parameter files is available to cover a given range. The files cover a certain range, the only change normally needed is the desired temperature.

Use the file which corresponds to a temperature above the one desired, e.g. to go to 40° C, use the 50degC file.

High Temperature Operation

The file names indicate the maximum temperature increase, e.g., 100degC is set up to reach 100° C, or 80° C above the temperature of the input gas. The major difference (aside from the desired temperature) is the heater power limit. If needed, the heater power limit can be adjusted.

For the upper range, the files are:


Name:       25degC         50degC      75degC     100degC 
Temp ° K       298           323         348        374
Heater %        5            50          65         80

To set up the temperature, use 'edte'. Read a parameter file, e.g., 100degC to go to +100 °. In 'edte' start with a low value, e.g. +25 ° C, then turn on the heater power. Up the temperature in 10 ° steps until you reach +100 ° C!

Low Temperature Operation

For low temperature operation, we have used the Bruker evaporator once for testing at -80 ° C. The parameter file is named "Evap-80C".

Our VT-Adaptor has been tested for both the LOW (-100 ° to -30 ° C) and MEDIUM (-30 ° to +25 ° C ) ranges.

The files are:

LOW Range:

Name:        Low-70C         Low-50C         Low-40C
Temp ° K        203.3           298.3          233.3
Heater %        70              85             90

MEDIUM Range: 

Name:        Medium-40C      Medium-30C      Medium-20C      Medium_0C
Temp ° K        233.3            243.3          253.3           273.3
Heater %        15               20             50              50


Calibration
Initial Vaules (10/7/92):

                        Indicated:      Actual:
                        373.0  K        374.5 K
                        193.0 K         191.5 K

NMR Facility Home Page
The College of Chemistry Home Page.

Questions, comments to: Rudi Nunlist rnunlist@bloch.cchem.berkeley.edu
Last Update: 9/26/95. RN