a cheap $15 sat-buddy type meter will work great for you. You can use it both to detect signal and on the other end to detect voltage. (since it is powered by the receiver it won't turn on unless your line has voltage.)
The other alternative is the built in signal meter, which if you suspect your box and not the wire is no good unless you have a second box that you know works. Also you could be almost certain the problem is the line in the wall but have it turn out to be the line to the groundblock/switch, and that is difficult to tell with just the meter box itself. Plus, if you do have the second box pulled from another room... did you remember how it was wired up or do you now have two boxes out? LOL
The other alternative for finding the wire in the basement that your box is plugged into is any type of voltage meter like a multi-meter. (or your tongue, not really recommended but a satellite box feels like a 9v batter does if that is the wire you stick to your tongue... but I would suggest making sure you don't have an electrical short or an old amplifier power source hooked into any coax lines first
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I don't usually suggest fiddling with your system unless you know what you are doing, but if you must you can find a simple signal meter on ebay for less than $20 and it is so helpful. Having a $10-20 meter around the house can be very cost effective... I would say about 33-50% of the service calls I get from my phone book service add could be fixed by the customer, or their "buddy" they always seem to have helping them, if they had one of these meters... That's cheaper than having a $75 directv service call, a $5 a month protection plan, or a $50 service call from me. (Unless of course you had the system installed by me in the first place, then you don't pay for your service call)
I carry two birdog meters on my truck, but I still have a couple sat buddies and an older metal meter because they are really useful as well.
