The sound reminds me a lot of an ATI. No wind-up, and no wind-down. If it had a wind-up and wind-down, it would sound a lot like a single tone 3016. This is the first Whelen I've ever heard that didn't have a wind-up.
Josh
Owner of a Federal Signal Model D Audio YouTube
For what its worth, for all of those I've heard, they've all had both wind-ups and wind-downs. I know that many of the oldest 3016s in the STL area have no wind-down, but that's the first 2000-R/400-R I've seen without one.