13C cpmas, X-channel at the probe, thru sgu-3; 300w from X-amplifier

for carbon 90 pulse calibration

pulse programe is  cp90av.jgh and used to optimize p1 @ pl11 
pl11 = 120 dB should give the same spectra as cpmas spectra,
for pl11 = -2 to 2dB, it should give zero signal or antiphase signal.
It is normal that aliphatic and aromatic carbon could have different 90 degree pulse.
Most of the time we settle with the moderate value.