I bought a Alternator and battery, and my 94 buick lasaber kills the battery i know it can be the starter?

but that works fine, dont here anything coming from it, something is pulling alot of juice out the battery, and its not the Alternator what can i o myself to diagnose.I bought a Alternator and battery, and my 94 buick lasaber kills the battery i know it can be the starter?Yes, The power antenna is a common source of a parasitic drain on the Le Sabre!