Converter Causing Generator Surge

Saying the generator was surging may be a misleading description. It does not rev up at all but rather dies down a bit the comes back up. The cause is not the generator as I have two, one is brand new and the other almost new. They both do the same thing individually and also when paralleled. It does this with no other load to speak of. I took the batteries out put a full charge in them and they tested good. Even though a Progressive Dynamics tech said the converter could not cause this I am having my doubts. Process of elimination does not leave much else.