Abstract: An NMR radio frequency (RF) surface coil allows the user to continuously vary the size of the field of view. The surface coil utilizes a modified radio frequency trombone for size adjustment that results in a stable resonant frequency of the coil over a wide range of dimensions such that retuning of the coil is unnecessary with changes in dimensions and variation of the field of view. The coil may be increased in area by as much as 60 percent while maintaining frequency stability to 1 MHz at 63.5 MHz and 2 MHz for full extension of 10 cm. The coil is readily adapted for imaging of the human spine, but can also be utilized for imaging other anatomical features.