Which control channels were you using? The closest site will probably be Forestdale/Adamsville, which is part of the simulcast cell. That CC is 855.6875.
Wenonah (853.275) and Gilmore (853.750) are the next closest sites. You won't hear as much activity on them though, as they only carry talkgroups that are currently being monitored by a radio affiliated with that site. This is especially true with Gilmore given its remote location and limited number of radios affiliated with it. The simulcast cell carries all traffic on the system, regardless of which site it originated from.
All of the sites I mentioned are within 10 miles of that general area. Unless your son lives in a terrible location for RF, you should be able to receive something with the stock antenna. If it helps, here is a map of the system:
jeffcotrs-1.jpg
