I was surprised at the difference three and a half megahertz made this evening.  While chatting with my friend Emily, N1DID, we started trying different bands to check for a better signal.  Fifteen meters was okay but twelve was better.  We decided to try ten meters for the heck of it and the almost full-quieting signal of Emily's was not heard at all just three and a half megahertz up the band.  Somewhere in that little bit of bandwidth the signal, instead of being returned to Earth via the ionosphere, was being shot into space with little hope that Emily would hear it.  I guess we found our maximum usable frequency!