Volts.

I installed a 3G 130 amp alt two weeks ago and at idle I see 14.75 volts. When I put my lights and radio on, the meter stays in that area it dosen't go past the half way mark. The second I turn the heater on full blast the charging drops dramatically (2-3 volts). I know that this isn't right considering my 65 amp alt was only a little bit less at idle with my heat and lights on. I'm pretty clueless, could it be the battery or a fusible link? The drastic drain is only when the heat is on full blast.
Also I don't know if this has anything to do with it but when I'm driving and pull in the clutch it will loop down to 600rpm and then up to the 700rpm I have set. :confused:
Thx for input and help. :banghead: