This paper presents an easy‐to‐build Fourier multinuclear magnetic resonance spectrometer operating, in the present case, below 100 MHz but readily adaptable to any magnet system. Receiver and transmitter are essentially made of commercially available wide‐band components. Some dedicated homemade circuits, necessary to the proper operation of the system, are described. A probe head has been especially designed for the observation of nuclei resonating between 6 and 36 MHz (nitrogen 14 to phosphorus 31), in addition to proton and fluorine (90 MHz and 84.6 MHz), without removing the sample and/or changing the spectrometer configuration. Interchangeable inserts are built in such a way that the measuring channel on the one hand, and the stabilization–decoupler channels on the other hand, are separated through the use of two orthogonal coils. Tuning and matching networks, which involve, for the measuring channel, homemade nonmagnetic capacitors variable in a large range, are described. The flexibility and the ease of operation of the apparatus are outlined.