My tuner also has a bad reception.
Do you power your antenna amplifier with the tuner's antenna-remote-out? I've only measured 9-10 Volts. Maybe every tuner with poor recption only has 9V on remote-out?
Which software are you runnning? After downgrading from 2.0B13 to 2.0 (or was it 2.0B11...) I had much better reception - still not as good as the original tuner though.

cheers
Thorsten