  The design of a wideband decimeter-wave (200 - 900 MHz) spectrometer with a
magnetic induction of up to ~ 10 T is described. This spectrometer is intended
for studying electronic - nuclear oscillations in antiferromagnets at low
temperatures (4.2 - 1.3 K). Critical field H_c = 2.5 +/- 0.3 T of a
reorientation transition in a noncollinear antiferromagnet Mn3Al2Ge3O12 at
temperature T = 1.3 K was determined from a 55Mn2+ NMR spectrum.
