You can bypass the media-center software and access the HDHomeRun tuner directly. In Windows, look for the program: Start > Programs > HDHomeRun > HDHomeRun Config (GUI)
When you launch this utility, you can enter a
real channel number directly, eliminating the possibility that the media-center software is limiting your choice of signals. Though raw signal strength is relevant, it alone is not the sole factor that determines reliable reception. Signal quality needs to be high enough to provide enough error free data to decode a viewable signal. (see the screen shots in post 1 of
http://forum.tvfool.com/showthread.php?t=820)
If you see signal quality of <60%, you may need to make changes to your antenna, it's location, aim or have other problems with cable connectors or amplifier noise/distortion.
If you're at the edge of reliable reception now, I would consider a Winegard HD-9095P + an RCA TVPRAMP1R preamplifier dedicated to azimuth 337° (magnetic) and terminated in a dedicated HDHR tuner. There are other options to consider when using more than one antenna,
http://forum.tvfool.com/showthread.php?t=2882.