Volume is good unless you are close and you may run off a turkey. With any call, turkey or locator, I like to start off soft and build up to loud and aggressive if I don't get a response. The sequence that has worked best for me is two or three sharp higher pitched bursts follow by a couple of raspier, aggressive notes that you drag out for a longer duration similar to the cadence suggested by Mark. Caw, caw, caw,..caaawwww, caaawwww. To get the aggressive notes, i flutter my throat and/or tongue like rolling a hoot owl note or aggressive purring on a mouth call.