  The three basic ingredients - a spinning compact object, an accretion disc
and a collimated relativistic jet - make microquasars a galactic scaled-down
version of the radio-loud AGN. That explains the large interest attributed to
this new class of objects, which up to now consists of less than 20 members.
Microquasars belong to the much larger class of X-ray binary systems, where
there exists a compact object together with its X-ray emitting accretion disc,
but the relativistic jet is missing. When does an X-ray binary system evolve
into a microquasar? Ideal for studying such kind of a transition is the
periodic microquasar LS I +61303 formed by a compact object accreting from the
equatorial wind of a Be star and with more than one event of super-critical
accretion and ejection along the eccentric orbit. For ejections at periastron
passage the relativistic electrons suffer severe inverse Compton losses by
upscattering the UV photons of the Be star at high energy: At periastron
passage Gamma-ray emission has been observed, whereas radio outbursts have
never been observed in 20 years of radio flux monitoring. For ejections
displaced from periastron passage the losses are less severe and radio
outbursts are observed. The radio emission mapped on scales from a few AU to
hundreds of AU shows a double-sided relativistic (beta=0.6c) S-shaped jet,
similar to the well-known precessing jet of SS 433.
