We present VLA-A radio continuum at 3.6 cm and H92α observations, and optical long-slit spectra at high spectral and spatial resolution of the compact Planetary Nebulae (PNs) Hu 2-1, IC 4997, IC 5117 and NGC 6884. The radio continuum maps show the subarcsecond structure of the PNs in detail. From the optical spectra, the basic kinematical properties can be deduced. The H92α emission line, spatially and spectrally resolved in IC 5117 and Hu 2-1, allows us to observe the kinematics of the PNs in spatial scales of ∼ 0.3″. By combining the radio and optical data, it is possible to identify the components present in the nebulae, to deduce their spatio-kinematical structure, and to obtain estimates for the electron density and temperature, ionized masses and kinematical ages. All this information permits to impose constraints about the mass ejection processes involved in the formation of PNs and when they have occurred.