  Using observations with e-MERLIN and the VLA, together with archival data
from ALMA, we obtain high-resolution radio images of two binary YSOs: L1551 IRS
5 and L1551 NE, covering a wide range of frequencies from 5 - 336 GHz, and
resolving emission from the radio jet on scales of only ~15 au. By comparing
these observations to those from a previous epoch, it is shown that there is a
high degree of variability in the free-free emission from the jets of these
sources. In particular, the northern component of L1551 IRS 5 shows a
remarkable decline in flux density of a factor of ~5, suggesting that the
free-free emission of this source has almost disappeared. By fitting the
spectra of the sources, the ionised mass-loss rates of the jets are derived and
it is shown that there is significant variability of up to a factor of ~6 on
timescales of ~20 years. Using radiative transfer modelling, we also obtained a
model image for the jet of the southern component of L1551 IRS 5 to help study
the inner region of the ionised high-density jet. The findings favour the
X-wind model launched from a very small innermost region.
