Really I don't bother even though it is used by Hens at times - It is a Turkey Call Competition sequence that is a waste of time. IMO.
Lovett Williams Real Voices CD has a good representative of the call. Yes I have heard it live and can mimic it but on a mouth call - however I don't use it.

Yelp or cluck or Purr and I to like to cutt!
All I need.

But a fly down cackle is like a sort of cutt sequence or just fast clucking followed by a yelp or two or even a 2 series cluck.

JW