[chopper]

Again, not trying to be a smart-aleck, but if you have had problems with multiple voltage regulators, perhaps the problem is in the alternator instead of the voltage regulator. Have you taken the alternator to a repair shop for testing? Most reputable shops will put your alternator on their test rig and give you a pretty complete analysis of its operation. That's what this repair shop in Florida did for me; he also asked that I bring the voltage regulator in along with the alternator, and that's how we found the particular problem. Just a thought, as it sounds like you may have a problem with the rectifier bridge circuit inside the alternator.