After removing the PFG coil assembly, you can see the Radiofrequency (Rf) coils that create the "B1" fields 
that we call pulses, and the same coils pickup (or detect) the NMR signal. In this view, you can see the outer coil, or the coil furthest from the sample. In this probe, this is the proton (1H) and flourine (19F) observe/decouple coil.
- The coil is the type often called a "saddle coil" because the current runs up one side, and down the other (like a saddle thrown over a horse).
- These coils are less efficient than Helmholtz-style coils; however, they are better suited for a secondary coil that surrounds the main detection coil.
- Both the saddle coil, and the Helmholtz coil create magnetic fields that are perpendicular to the vertical axis (or main B0 field), which is, of course, a requirement.
- Difficult to see in the photograph is the fact that the B1 field from the outer coil is perpendicular to the B1 field generated by the inner coil (shown in the next picture). This is important to prevent the Rf current from one coil from inducing a current in the other coil (or, to isolate them from one another).