Slee, all I can tell ya is, 150yds is well within a gobblers range. they' ll range out a good bit further than that, but 150yds sounds like a good set up spot from the nest. but, if your not hearin any gobbles, seein any gobbler droppins, tracks, etc then it might be time to move on to another spot. because if there' s a gobbler roostin around there close, you should hear him or at least see some sign.
I' ve always heard that when the hens are settin then the gobblers will roost close to them, but keep in mind, that there' s more hens than gobblers, so I think I' d be lookin for a more promising place, where there' s gobbler sign.