There are a lot of rumors circulating that the Soviet Union received the Iranian F-14 Tomcat. Iranian F-14 was ever ‘given’ to the Soviets. The Soviets made parts for TF-30 engines of Iranian F-14s. Soviet Union has developed the Zaslon radar or the R-33 missile for their MiG-31 on basis of any kind of intelligence – from Iran.
It doesn’t matter who in the West has released any of such rumors, all are wrong. The Soviets were never left even anywhere close to any of Iranian F-14s.
Similarly, all the photos purportedly ‘showing ex-Iranian F-14s undergoing testing (“against MiG-25s”) in the USSR’ – are fake.
The Soviets did not need to ‘steal’ or ‘get’ any Tomcats: obtaining quite good intel on the F-14 – from the USA – proved quite easy for the KGB.
Perhaps ironically, the rest came from diverse of books. Gauging by specific illustrations in Soviet internal publications, they did make extensive use of Mike Spick’s ‘Modern Combat Aircraft: F-14’ (Salamander, London, 1983).
Already in the same year, the Soviet air force published a related booklet ‘Naval Fighter F-14 (US Navy)’ – see the attached scan. BTW, this was ‘nothing special’.
They’ve had such ‘tactical manuals’ for all other major types of Western aircraft, too – including F-4s, F-15s, F-16s, F-111s, E-2C, E-3A, even for the F-117A and the B-2A: arguably, only top-ranking fighter pilots were getting these to see (the reason for this was the – ‘complex’ – training system for all their pilots), which is why they remain relatively unknown outside specific circles.