After re-reading my post, let me amend it a bit. Start on page 30 at "Flywheel Alternators" and read through page 32. Mine is a 20A, but you could even have a 15A. You could also have a 30A, I suppose. Mine charges at 14.3-14.4V anytime the engine is much above idle, and has plenty of current for 91JF's meager needs.
See http://www.twinslan.net/~n0nas/manuals/onan/940-0751%20Onan%20NH%20(RV%20spec%20J-P)%20NHC,%20NHCV%20(spec%20E)%20Engine%20Service%20Manual%20(04-1987).pdf Pages 31 and 32 are all you need to test regulator and generator. This is a "Synchro 20" I have this dumb-as-dirt single-phase system also, and it is surprisingly smooth voltage with zero EMI noise on the radio, or the rest of the system, best I can tell. Given that these use permanent magnets, it is certainly conceivable that they could lose their magnetism over time, but I wouldn't expect it to happen quickly. Regulator would be my first guess. Mark Langford ML at N56ML.com http://www.n56ml.com
