The Russian avionics site I linked to the other day (
http://www.overscan.co.uk/Avionics.html) says this about the MiG-31 radars:
Quote:
Zaslon-A - security of the Zaslon system was compromised by the US spy A Tolkachov. This lead to development of an updated version, fitted to MiG-31B from 1990, retrofitted to some earlier models during rebuilding to MiG-31BS standard. It had a new data processor, giving extended capabilities, longer range and better ECM resistance.
I think R-33S is the version "matched" to the updated radar, and may have slightly improved capabilities.
Zephyr