A considerable amount of work has been put into the rf probe design for the 3-dimensional rotating frame NMR imaging method, at 5 MHz, as an extension from our previous 2D projects. Because of limitation in geometry, the coils interact strongly rendering impossible individual tuning and matching by conventional means. We have successfully devised circuits to overcome these difficulties. The same principle can be utilized in other similarly coupled rf coils. Existing softwares are modified and expanded to accommodate the new hardware for data collection and reduction. A FORTRAN program package is being developed to give numerical solutions to the Bloch-Riccati equations for arbitrary rf pulses. A preliminary investigation has been conducted with regard to spectral treatment by the maximum entropy method, which has been introduced to the NMR field recently to improve the signal-to-noise ratio.