A pair plasma model for PKS 0208-512

Assuming that the enhanced MeV emission from the MeV blazar PKS 0208-512 ob served by COMPTEL on occasions is due to annihilation in a pair plasma, we estimate parameters of the annihilation region: its size, the number densit y of particles, and the variability timescale. The values we find are in ac cord with our present-day knowledge of emission mechanisms operating in AGN . The constructed model implies that the blueshifted annihilation emission is an intrinsic property of all AGN jet models. and predicts an anticorrela tion between the high-energy emission and the annihilation flux.