I've had fair to good results with diaphragm turkey calls. You can get howls, barks, squeals, squeaks, trills... My best experience has been at dusk and dawn. I have had coyotes pull cat like stalks on turkey decoys. Where to call? Good question. Walking in a ways seems to be better. With all the electronic high volume calls, you might want to be a little more stealth like and call with less volume to a smaller area and move a lot. An elevated hide can be a benefit. Take care, have fun...