  Blazars are among the most variable objects in the universe. They feature
energetic jets of plasma that launch from the cores of these active galactic
nuclei (AGN), triggering activity from radio up to gamma-ray energies. Spatial
localization of the region of their MeV/GeV emission is a key question in
understanding the blazar phenomenon.
  The flat spectrum radio quasar (FSRQ) PKS 1502+106 has exhibited extreme and
correlated, radio and high-energy activity that triggered intense monitoring by
the Fermi-GST AGN Multi-frequency Monitoring Alliance (F-GAMMA) program and the
Global Millimeter VLBI Array (GMVA) down to $\lambda$3 mm (or 86 GHz), enabling
the sharpest view to date towards this extreme object.
  Here, we report on preliminary results of our study of the gamma-ray loud
blazar PKS 1502+106, combining VLBI and single dish data. We deduce the
critical aspect angle towards the source to be $\theta_{\rm c} = 2.6^{\circ}$,
calculate the apparent and intrinsic opening angles and constrain the distance
of the 86 GHz core from the base of the conical jet, directly from mm-VLBI but
also through a single dish relative timing analysis.
  Finally, we conclude that gamma rays from PKS 1502+106 originate from a
region between ~1-16 pc away from the base of the hypothesized conical jet,
well beyond the bulk of broad-line region (BLR) material of the source.
