I'm horrible at foreign languages but did you check this list of stations?

http://www.geocities.jp/binewsjp/bib09.txt

One other possibility is if you are certain it's Russian, could be a
harmonic of 1500-1600khz transmissions.

I get several strong signals on 90 meters here in the states at night
from US domestic shortwave broadcasters and some weaker spanish stations
from the topics.

Good luck.