BBP Probe Tuning on NMR400

The broadband probe on NMR400 (BBP, or Varian name ATB) can be tuned to H1/F19 and X-nucleus ranging from N15 to P31 in frequency. The tuning capacitors (or sticks) are in the probe Box labeled BBP/ATB. Be very careful not to touch or bend the tips when handling the capacitors.

NOTE: The default setting on this probe should be left tuned for C13 with the capacitor stick labeled 6.8.

NMR400 has only one Preamp box (dualband Preamp) for both high (H1/F19) and low (X-nucleus) frequencies. Follow these steps to tune to the desired nucleus frequency:

Tuning for H1 and F19

Tuning for X-nucleus

Step 1: Set nucleus from console

Step 2: Check what tuning stick to use

ATB Tuning capacitors

Step 3: Insert tuning capacitor to probe bottom slot (P31 does not need a tuning capacitor)

BBP/ATB probe bottom

Step 4: Connect cables for tuning

Step 5: Install correct 1/4-wavelength filter

Step 6: Return cabling for experiment

Step 7: Note recent arrangement with the Hayton group regarding NMR400 does not require X-channel to be tuned back to any default nucleus after the experiment. But, if the probe has been tuned for F19 detection, the following must be done.

H. Zhou updated October 2011