Dedicated spectrometers for terahertz radiation with 0.3,30 THz frequencies using traditional optomechanical interferometryare substantially less common than their infrared and microwavecounterparts. This paper presents public documentation for thedesign and initial performance measurements of a tabletop Fouriertransform spectrometer (FTS) for terahertz spectral analysis usinginfrared optics in a Michelson arrangement. This is coupled to abroadband pyroelectric photodetector designed for 0.1, 30 THzfrequencies. We measure spectra of narrowband and broadband inputradiation to characterize the performance of this instrument above10 THz, where signal-to-noise is high. This device is constructedin the context of research-and-development for the recently-proposedBroadband Reflector Experiment for Axion Detection (BREAD), wherethe optical components can be applied to ongoing efforts for testingthe pilot experiment.