(These instructions assume you are familiar with basic Macintosh procedures, if you are not, see a Macintosh manual or the tutorial which is on most Macintosh computers. Throughout the following, MB means mouse button.)
The probe should be tuned prior to RF field calibration.
Use a sample that will yield good S/N in one scan. Open the H1setup or C13std file in the setup filesgn folder. Open the pulse sequence window and set the pulse width to 7u (u means microsecond). Collect and process one scan, then properly adjust the spectrum phase. Set the pulse width near the time corresponding to a 360 degree pulse. The approximate 360 degree pulse widths and associated power levels for the 5mm probe are: proton - power level 63db, 360 degree pulse 32u; carbon - power level 61db, 360 degree pulse 60u. Collect, process and apply the previous phase correction to the spectrum. Note the appearance of the peak intensities and phases. Collect two more spectra, one with a pulse width 2us smaller than the original spectrum and one with a pulse width 2us shorter. The peaks in spectrum collected with a true 360 degree pulse will have little or no intensity compared to the pulse width = 7u spectrum and any intensity will be equally distributed above and below the baseline. If most of the intensity in the near 360 degree pulse spectrum is positive then the magnetization has been rotated > 360 degrees: if most of the intensity is negative, the magnetization has been rotated < 360 degrees. Collect spectra with different pulse widths until the 360 degree pulse width is found, then divide by 4 to get the 90 degree pulse width.
The following description assumes one is observing C-13 with the 5mm probe.
Put the dioxane, benzene standard sample in the probe, then lock and shim. Calibrate the C-13 observe pulse as described above. Go to the setup filesgn folder and open the decrfcalib file. Open the pulse sequence window and go to the EVENT row. Go to the EVENT #4 box and then go down one row to the Name: column, this box contains the text H90. Put the cursor in the H90 box and click the MB, change the Delay value to 1u. Collect four scans and properly adjust the phase of the high field peak. Change the H90 Delay value to 12u, collect 4 scans and process. Note the peak intensity. Collect two more spectra with H90 Delay values of 10us and 14us and note the intensities. The pulse width that yields the minimum high field peak intensity is the 90 degree pulse width (it should be near 12u). If no minimum is found continue changing the H90 Delay in the direction that gives lower peak intensity and look for the minimum.
The decoupler power level (DCP_LVL in the pulse sequence) for the above calibration is 125. This is the power level typically used when one uses the decoupler to do pulse sequence proton pulses. One should set DCP_LVL (in the pulse sequence) to 88 in order to calibrate the decoupling field typically used during acquistion of C-13 and P-31 spectra. DCP_LVL equal to 88 in the pulse sequence corresponds to a Decoupler Gain setting of 56 db (in the DECOUPLER (F2) section of the FREQ window). When DCP_LVL is set to 88, the 90 degree pulse width will be near 66u.