  This thesis describes the development of an ultra-low noise sapphire
resonator oscillator that is tunable over X-band. While undertaking this task
the author has explained some interesting and very useful phenomena in regards
to the design and understanding of multi-mode resonant cavities and
oscillators. The oscillator was constructed to operate as the pump oscillator
in the superconducting parametric transducer system, attached to a 1.5-tonne
niobium resonant bar gravitational wave detector. The effects of incorporating
the pump oscillator with the parametric transducer and resonant bar system are
analyzed to enable prediction of the detector sensitivity. The detector was the
first massive precision optomechanical system ever built. With the resurgence
in interest in resonant detectors, this thesis has important work on multi-mode
acoustic systems, coupled to a highly sensitive parametric transducer relevant
for many fields of research today.
