Thanks for all the advice. I made two quick stands before going to work (I sometimes work evenings). I was hunting in an area I had scouted the week before where I had found a fair ammount of coyote scat along the trails.
On my first stand, using a much lower volume than I had been using, I managed to call in a hawk that came within a foot of grabbing my speaker. Pretty cool.
On my second stand I had to leave after only 30 minutes of calling. As I was walking out I spotted a coyote 108 paces from my stand (I'm over 6' tall). I was packing a shotgun, so I did not take the shot.
Thanks again for all of the advice. I think I will have to wait until this weekend until I get to do anymore calling.