  In this paper we comment on the possibility for intermittent jet activity in
quasar 3C 273 on different time-scales. We propose, that striking morphology of
the large-scale radio jet in this source, as well as the apparent lack of its
counterpart on the opposite side of the active center, may be explained in a
framework of a restarting jet model. In particular, we propose that 3C 273
radio source is intrinsically two-sided, and represents an analogue of
double-double radio galaxies, but only inclined at a small angle to the line of
sight. In this case, the apparent one-sideness of the kiloparsec-scale radio
structure may be due to combined Doppler and time-travel effects alone, if the
3C 273 large-scale jet itself is relativistic and matter-dominated. We also
propose, that knotty morphology of the discussed jet, which is observed now
additionally at optical and X-ray frequencies, indicates modulation in the jet
kinetic power. This, together with the variability of the jet at small (parsec)
scales, indicates that the jet activity in 3C 273, and possibly in other
similar sources, is variable/modulated/intermittent over many different
time-scales.
