This paper outlines an infrared spectroscopic technique to measure the radial velocities of faint secondaries in known single-lined binaries. The paper presents our H band observations with the CSHELL and the Phoenix spectrographs and describes detections of three low-mass secondaries in main-sequence binaries: G147-36, G 164-67, and HD 144284, with mass ratios of 0.562± 0.011, 0.423 ± 0.042, a...
