Can I use an ordinary scanning receiver?

Scanning receivers are much cheaper than those designed for radio-tracking, because their market is much larger. Unfortunately, even though you may be able to hear your tags on such a receiver they are no good fro radio-tracking. The vast majority do not have gain controls and most are frequency modulated, to try and keep the signal the same volume, both of which make them useless for direction finding. Moreover there are hidden complications to do with how the signals are mixed in the front end that may mean you caon not hear certain tags at any distance, or when another signal interferes. This si more difficult to check, but will lead to problems.