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--- playground:nmr [2012/03/09 09:46]
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+++ playground:nmr [2012/03/15 09:51]
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    - The TANDEM window will inform you of how many steps needed to move approximately to the frequency you entered.
    - When the NMR advances this number of steps it will inform you of the frequency the NMR has moved to at this step position.
-   - If this frequency is not close enough to the desired frequency, repeat the nmrgoto command and it should get closer.  The NMR moves to the entered frequency by estimating the number of steps needed to advance from the current position and then moving that number of steps.  The closer you are to the desired frequency, the closer the end result will be.
+   - The NMR frequency is read directly on the console on the Agilent 53131A Universal Counter located directly above the NMR.  The counter that is read by the computer is on the left and is the standard counter to use for the NMR frequency.  The NMR may also be connected to the similar counter on the right to allow comparing the frequency readout.  The accuracy of the NMR is determined by the accuracy of the counter so if there is disagreement in the counter frequency it needs to be checked.  The counters should agree to 7 digits.
+   - If the counter is not updating the frequency readout you need to press the "Run" button on the counter.  These counters go into remote mode when read by the computer and need to be manually placed on local mode by pressing the "Run" button.
+   - If this frequency is not close enough to the desired frequency, repeat the nmrgoto command and it should get closer.  The NMR moves to the entered frequency by estimating the number of steps needed to advance from the current frequency and then moving that number of steps.  The closer you are to the desired frequency, the closer the end result will be.
    - Set the FIELD SWEEP control to the optimum position.  The optimum setting will be near 15 for the upper three ranges of the fluxmeter and near 5 for the lower three ranges.
    - set the VERTICAL GAIN control for approximately 1/16-inch of "grass" on the face of the oscilloscope.
-   - Now that the NMR is set to a frequency slightly lower than the frequency you want the magnet to be set to we can begin slowly increasing the analyzer magnet control upward toward the current that will show a resonance on the NMR.  Typical resonance patterns can be are described in the {HVEC_NMR.pdf|Original HVEC NMR Manual} figure 1.  Remember that because of magnet hysteresis and saturation effects, we can only increase the magnet current from this point on.  If we decrease the magnet current we will have to recycle the magnet and start over for an accurate NMR flux value.
+   - Now that the NMR is set to a frequency slightly lower than the desired frequency, we can begin slowly increasing the analyzer magnet control upward toward the current that will show a resonance on the NMR.  Typical resonance patterns and control positions can be seen in the {{HVEC_NMR.pdf|Original HVEC NMR Manual}} figure 1.  The resonance will enter the display from the right side and move across the CRT display from right to left.  When the resonance is found and centered on the CRT display, the magnet flux (frequency) can be read on the HP counter located above the NMR Fluxmeter.  Remember that because of magnet hysteresis and saturation effects, we can only increase the magnet current from this point on.  If we decrease the magnet current we will have to recycle the magnet and start over for an accurate NMR flux value.
-   -
   * {{HVEC_NMR.pdf|Original HVEC NMR Manual. Main frequency adjustment control and tracking feature now obsolete.  See above new procedures.}}

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