2) Manual Tuning – Tuning the 500 Penta Probe
Probe tuning on the Varian 400 and Varian 500 is dependent on which probe you are using. The Varian 400 usually has the autox probe installed, which will auto-tune to 1H (and 19F) on one coil, and many X nuclei on the other coil (13C, 31P, 11B, etc). However the 500 MHz penta probe is set to manual tune because the tuning capacitors are extremely sensitive and can break easily. Any time you want to acquire data on the NMR500 with the penta probe installed, you should tune the probe manually if you are collecting data other than a routine 1H experiment. This includes 13C, 2D HSQC or COSY, Solvent suppression, Wet1D, etc. Really… Anything other than a routine 1H experiment requires probe tuning. This is because the calibrated 90 degree pulse lengths (see later video) are dependent on properly tuned and matched RF coils. This video goes through how to tune the penta probe.
