The very best locator call I've ever used is the pileated woodpecker call. It's piercing and can shock a bird into gobbling without, it appears to me, being threatening.
I first heard a pileated woodpecker in the woods, probably 30 years ago, and a turkey gobbled almost immediately. It was mid day and I had not heard or seen a thing until that time.
At some point, I found a pileated woodpecker call made by Haydel's Game Calls, Inc. Model PW-90. I still have that call.
A word of warning. This is not a call that you practice in the car, in your home, in any enclosed space or anywhere else a wife or family member might be present. Some type of ear protection is also highly recommended!
"If he's out of range, it just means that he has another day and so do you."