In 2009 I made a rookie mistake - after owning a couple of yagi style integrated antennas I tried a DB8 and it failed to impress, I discovered why and how to fix it. The problem was that the old antennas had an amplifier built into the rotor and the new one did not. By adding the pre-amplifier signal quality jumped, I used an inexpensive one from Antra Antennas but I've now seen people using ones from The Source and other online vendors.
American Channels are usually foolproof due to signal strength, so when I failed to get a lock on any station it was clear there was a problem. The Pre-amplifier solution provided valuable information about the true quality of the DB8. I still find that my Yagi is better at getting SunTV (66) and Global (41) from Toronto for now. I will probably swap back to the DB8 in August 2011 and add a single VHF wire specially tuned for Channel 3 from Barrie.
Don't make the rookie mistake of forgetting your pre-amplifier when you install your outdoor antenna.
This problem supposedly exists on both sides of the border when people receive affordable antennas from overseas lacking information about signal dissipation. If you plan on running without a pre-amp you may have to swap from unbalanced 75ohm coaxial lines to balanced 300 ohm twin-lead. This was the type of wire you used to see on the back of television receivers connected with two screws.
Feel free to use my search box for more information about yagi, db8, and other antenna gear or take a peek at the antenna array that I use now. Here: http://www.kurtismccartney.com/antenna