MythTV PVR250 - Everything works, fine tune picture????

[SqwkVFR]

Many thanks to all of you who have posted in support of mythtv. I got everything up and running, and it works well. Now I need to fine tune the picture. I have a PVR250 (tuner type 39) and the picture I get, whether in Mythtv or by cat video0 > file, is always fuzzy, like the tuner isn't quite tuned correctly? Back in windoze, the pic looks great, so I know it's not the hardware or the connection. How do I fine tune the tuner freq's??? Thanks in advance.