  Recent reports of possible correlations between high energy neutrinos
observed by IceCube and Active Galactic Nuclei (AGN) activity sparked a burst
of publications that attempt to predict the neutrino flux of these sources.
However, often rather crude estimates are used to derive the neutrino rate from
the observed photon spectra. In this work neutrino fluxes were computed in a
wide parameter space. The starting point of the model was a representation of
the full spectral energy density (SED) of \textit{3C 279}. The time-dependent
hybrid model that was used for this study takes into account the full $p\gamma$
reaction chain as well as proton synchrotron, electron-positron-pair cascades
and the full SSC scheme. We compare our results to estimates frequently used in
the literature. This allows to identify regions in the parameter space for
which such estimates are still valid and those in which they can produce
significant errors. Furthermore, if estimates for the Doppler factor, magnetic
field, proton and electron densities of a source exist, the expected IceCube
detection rate is readily available.
