  We study the correlations between the jet ejection event and changes in the
continuum emission of the radio-loud galaxy 3C 390.3, using the archived
monitoring data in radio, optical and X-ray. We present evidence for the link
between the variable optical continuum and a stationary radio feature in the
jet. The ejection of radio components happens during, or after, the dip in the
X-ray light curve. Moreover, during the X-ray dip the flux variability is
significantly reduced while the hardness ratio and its variance becomes harder.
These findings strengthen the idea of similarity between active galactic nuclei
(AGN) and microquasars, pointing towards a common physical mechanism acting in
the disk-jet system. Other similarities are also discussed on the basis of
comparision between 3C 390.3 and the microquasars GRS 1915+105 and Cyg X-1. If
the analogy (based on linear mass scaling) between the ejection rates of the
microquasar GRS 1915+105 and 3C 390.3 is correct, then the rate of ejections in
3C 390.3 should vary between ~(0.01 to 1) ejections per year on a time scale of
thousand years.
