Ford Repair: Alterator?, volt meter, alternator

Question
I started having problems with my '89 Probe the other day. It seems as though my alternator is charging my battery but not to the extent that it should be. I tested my battery to make sure that it wasn't the problem, and my battery is fine. I checked all of the connections to my alternator and the belts and everything seems to be in fine working order. As far as my experience has been, when the alternator goes it just flat out stops chargin the battery, but for some reason mine will charge it a little and then as soon as i do something like turn on my headlights or my stereo, it just drains my battery within a minute or two. Would you have any suggestions as to what it could be? Thanx for your assistance. - Dave

Answer
Hello and thanks for the question... I'll try to help.
 You said you tested your battery? How? If you mean by checking the voltage with a volt meter, that isn't a complete test. You need to do an amperage test on it. I would suggest you bring it to Sears or another place to have the battery fully tested.
 As far as the 1/2 charging goes........it is very possible to have an alternator do that.
First have the battery checked out and if that is Ok, I would suggest replacing the alt.
Hope this helps,
Erik