A clamp assembly is provided with a first clamp portion and a second clamp portion. The evaluate pulse may be generated from a clock signal such that it is shorter in duration than the clock signal. A four element band pass birdcage coil comprises two square end ring segments, each end ring segment comprising four sides of equal length, and four rungs of length equal to a side of the end ring segment, and wherein four rungs join in respective corners of the end ring segments. This configuration allows the LNT to operate at temperatures higher the than first device and facilitates independent control of the LNT and first device temperatures.