The primary mode of target acqusition is using the IADS (where we know our target).
Anything else is only backup solution.

In Hungary, we not bought the IFF for the RPC at all.
(Now, both are in a museum at Kecel)

I see.. But the manual says that little antenna on side of the RPC is the IFF receiver. I thought it was organic from the S-200!
Very good, thanks for the info.