Patent ID: 7701219

Claim:
A nuclear magnetic resonance apparatus comprising: a nuclear magnetic resonance sample coil; and a switching assembly electrically connected to the sample coil, comprising a first pair of contacts disposed along a longitudinal channel, at least one contact of the first pair of contacts being electrically connected to the sample coil, a second pair of contacts disposed along the longitudinal channel and spaced apart longitudinally relative to the first pair of contacts, at least one contact of the second pair of contacts being electrically connected to the sample coil, and a longitudinally-movable switching member comprising a plurality of longitudinally-spaced capacitors including three or more capacitors, the switching member being positioned in the longitudinal channel such that different subsets of two capacitors selected from the plurality of capacitors are capable of being inserted between the first pair of contacts and between the second pair of contacts, wherein a longitudinal motion of the switching member alters a contact state of at least two of the different subsets of the capacitors with the first pair of contacts and the second pair of contacts, thereby adjusting a resonant frequency of a nuclear magnetic resonance measurement circuit including the sample coil.