We describe a setup consisting of a ferromagnetic resonance (FMR) cavity and an ultrahigh vacuum (UHV) chamber. The magnetic sample under UHV can be moved into a quartz tube finger which is an integral part of the UHV chamber. This 2-cm-o.d. finger can be inserted with a small clearance into the entrance hole of a cylindrical microwave cavity. The FMR absorption versus applied magnetic field spectra were measured at various angles theta between the applied magnetic field and the sample plane for Co films deposited in situ on a Si(111) surface. When the finger is withdrawn from the cavity, the hysteresis loop of the magnetic sample can be measured using the surface magneto-optic Kerr effect.