it shudnt do as with Digital you either get a signal or you dont.
I'd spend a bit more and get something like the I-Can Freeview HD 2851T instead. You can find it for just under £50. It also has a BBC iPlayer option on it as well.
Those Technika HD boxes were on the Tesco website for £15 the other day as well. Don't seem to be on there now though.