[en] The proposed multi-purpose isochaonous cyclotron U-250 with a pole diameter of 250 cm is designed to accelerate ions with A/Z=2 to 6 (from proton to argon) with energies above the Coulomb barrier, and ions with A/Z <= 10(Fe, Ni, Kr) to energies higher than 1-2 MeV/nucleon. Similar to the U-200 and U-400 cyclotrons, its magnetic poles have four sectors, and the r.f. accelerating system consists of two 42 deg dees with quarter-wave lines. The frequency range lies between 7.5 and 15 MHz, and the operating harmonics are the first to the fourth ones. The maximum energy of the accelerated particles is W=204Z²/A. Owing to the small gap, at the chosen value of maximum magnetic field in the centre (1.9 T) the power consumption per unit of energy of accelerated particles is low