The magnetic properties of the Sr(Ba) Zn xMn 2- xFe 16O 27 series ( x = 0.0, 0.66, 1.0, 1.33, 2.0), prepared with a ceramic method, are examined. The Tc of the compounds is 430-375°C. The saturation magnetization M0, anisotropy field HA and high field susceptibility χ 0 are obtained from an analysis of the isothermal curves according to the law of approach to saturation, in fields up to 180 kOe. M0 values 71-78 emu/g, increasing with Zn content and HA ≈ 11.5 kOe at RT were found. The difference between experimental and theoretical magnetization at 4.2 K, together with the high χ 0 values observed, indicate the existence of a random spin canting.