Why even early helicopters threatened wartime submarines

Would vibration-sensitive vacuum tubes and transistors make early anti-submarine helicopters impractical?

They created engineering challenges, but even early helicopters were fast enough to patrol against slow, surface-dependent wartime submarines.

Vibration-sensitive electronics posed engineering problems for early naval helicopters, but the aircraft still had a large mobility advantage over their targets. A Type VII managed about seven knots submerged and drained its batteries quickly, while on the surface it remained slower than a roughly 90-knot helicopter. Second World War submarines were closer to submersible torpedo boats than the fast, continuously submerged boats familiar from Cold War experience. That difference makes modest early rotorcraft performance much more useful than a modern comparison suggests.