Some issues are presented on the rf system in the future Fermilab pre-booster, which accelerates 4 bunches each containing0.25×1014&hthinsp;protonsfrom 1 to 3 GeV kinetic energy. The problem of beam loading is discussed. The proposal of having a non-tunable fixed-frequency rf system is investigated. Robinson’s criteria for phase stability are checked and possible Robinson instability growth is computed. ©1998 American Institute of Physics.