Hi, thank u for your answer.
I can not think the alternator is wrong, for this reason I point to the cabling problem (which I also doubt becasue the connections are aparently right), your advice is a good test, I will do as you mentioned; with a good cable from battery minus to groung. Also my big doubt is the belt tension, becasue I can not tight much more the manual adjustment with the alternator, I have thought to make a wood cradle to insert betwen the alternator and the engine block to tight more the belt.
I will comment u
Best Regards