I was sent this lot as an email and thought that someone may be interested - This includes radios and instruments. I have not downloaded any so cannot comment on them
Aircraft MiG-21FL. Technical description. Book 4. Electrical and oxygen equipment and flight instruments. Part 1 . Aircraft MiG-21FL. Technical description. Book 4. Electrical and oxygen equipment and flight instruments. Part 2 . Freedom of Information Act Electronic Reading Room | CIA FOIA (foia.cia.gov)
Decided to go hunting as the person who sent it to me is never that tidy when doing an email and found that the Russian Air Force Museum at Monino has an equivalent to our magic archivist VikingBeserker who goes by the handle Something and he is the major poster in the 25 page thread of manuals is at Книги по матчасти Look for his avatar
Note that different translation software may translate his name differently. I use Imtranslation