Studies are described of the ferrimagnetic garnet system Eu3Fe5—xGaxO12. It is shown that a compensation point of the net angular momentum occurs atx≅1.2, at which the resonance linewidth remains narrow. In all previously observed ferrimagnetic systems with angular momentum compensation points, e.g. GdIG, strong line broadening occurs. The reasons for this are discussed together with the relaxation processes involved. Application of the resulting largegfactors to millimeter wave harmonic generation is considered.