Unless you are in one of those few areas of the country that is dominated by people who grew up elsewhere - i.e., Florida, California, or Las Vegas - I would think that it would be difficult to find a Patriots bar, or for that matter any bar that caters to a specific out-of-town team. The same holds true in reverse; for example, how many Eagle/Philly sports bars are there in the Boston area?
There are two things going for you though. One, the Eagles have a bye in week four so they're not on tv. Second, the Pats-Ravens is the best early game on the NFL schedule. That means there's a good chance that they'll not only be on, but will be the primary game on the big screen and you'll have the sound on as well. The ony reason they won't be on is if some places in Philly elect to show one of the two NFC East games that are on at the same time instead.
Bottom line is that even though there might not be any Pats bars in Philly, there should be several places playing the Pats game with the sound on.
