The stability properties of Alfvén Eigenmodes (AE's) are investigated directly using external antenna excitation and detection of stable modes in a variety of plasma configurations in different devices. Dedicated methods to measure the AE damping rate separately from the fast ion drive have been pioneered at JET, using low toroidal mode number internal saddle coil antennas. Other experiments have since installed localised in-vessel antennas to drive and detect MHD modes in the Alfvén frequency range, first on C-Mod, then on MAST. A new antenna system, comprising two assemblies of four toroidally spaced coils each, was developed on JET to replace the low-n saddle coil structure and excite AE modes in the toroidal mode number range that is expected to be most unstable in ITER, n~5-15. Experiments on C-Mod proved for the first time that intermediate n TAEs can be driven and detected, and point out significant differences with respect to the low-n regime on JET in the values and scaling of the damping rate with plasma parameters, e.g. the edge shape. Experiments with the first four-coil antenna on JET confirm that excitation is possible in a large volume plasma, together with real time tracking of core modes throughout the limiter and divertor phases of high performance discharges, with significant additional heating. The similarities and differences between the active MHD antenna systems, as well as the first results on C-Mod, JET and MAST are illustrated. Both C-Mod and JET results underline the fact that a precise reconstruction of the mode spectrum and its structure, important for a quantitative comparison with theoretical models, represents a significant challenge in the intermediate n range and in the presence of several modes.