  Context. SS 433 is historically a well-known microquasar in the Galaxy that
has been deeply studied during the four decades elapsed since its discovery.
However, observations at very high radio frequencies with good angular
resolution are still very scarce in the literature. The present paper tries to
partially fill this gap using archival data of the source obtained with the
Atacama Large Millimeter Array (ALMA). Aims. We aim to study the SS 433 jet
properties at radio frequencies corresponding to millimetre wavelengths where
the synchrotron emitting particles are expected to lose their energy much
faster than at lower frequencies of centimetre wavelengths. Results. A resolved
view of the SS 433 radio core and jets is presented. In addition to spectral
index and magnetic field measurements, we are able to estimate the age of the
oldest visible ejecta still radiating significantly at millimetre wavelengths.
By combining our findings with those of previous authors at lower frequencies,
we confirm that the energy loss of the radiating electrons is dominated by
adiabatic expansion instead of synchrotron radiative losses. In addition, we
find suggestive evidence for the previously proposed period of slowed expansion
within the first months of the ejecta flow, needed to simultaneously match the
radiative lifetime observed in the centimetre domain. Our results argue for the
need for future coordinated millimetre and centimetre interferometric
observations with good time sampling throughout the SS 433 precessional cycle
to better understand energetic processes in stellar relativistic jets.
