  shortened) Results obtained from 9 X-ray observations of 3C 273 performed by
ASCA are presented (for a total exposure time of about 160 000 s). The analysis
and interpretation of the results is complicated by the fact that 4 of these
observations were used for on-board calibration of the CCDs spectral response.
  The present analysis shows that, in agreement with official recommendations,
a conservative systematic error (at low energies) of about 2-3 x 10**20cm-2
must be assumed when analyzing ASCA SIS data. A soft-excess, with variable flux
and/or shape, has been clearly detected as well as flux and spectral
variability. An anti-correlation is found between the spectral index and the
flux in the 2-10 keV energy range. Fitting the data with the latest available
calibration matrices, we also detect an emission line at ~5.4-5.7 keV (~6.3-6.6
keV in the quasar frame) in (only) the two observations with lowest fluxes
where it is weak (EW ~ 20-30 eV), narrow and consistent with being produced by
Fe K emission from neutral matter.
  Overall, the observations are qualitatively consistent with a variable,
non-thermal X-ray continuum emission, i.e., a power law with Gamma~1.6
(possibly produced in the innermost regions of the radio-optical jet), plus
underlying ``Seyfert-like'' features, i.e., a soft-excess and Fe K line
emission due to a reflection component. When the continuum (jet) emission is in
a low state, the spectral features produced by the Seyfert-like spectrum
(soft-excess, iron line and possibly a steep power law plus reflection
continuum) are more easily seen.
