97 Saab 900 Convertible
 

I have a 97 Saab 900 convertible perfect car for the spring and fall in texas.
But I am starting to have a major problem with it now . My alternator keeps going out first one lasted about 100 miles replaced it and now this one lasted about 600 miles. Does anyone know what could be causing this problem ? Or are the alternators from Advanced autoparts just junk?