Cranks but won't start. Unplug ground at field spade on Alternator and it starts?

Some progress: I see .06 volt drop to + side of coil while cranking engine. Also see 11.5 volts at coil when cranking same as battery. This was with ballast resistor unplugged.

With ballast resistor plugged in but Unilite unplugged I get .35 voltage drop to coil. In this test current flows through ballast and 3.5 amps flows through field circuit to alternator. So it puts a bit more load on the circuit but seems to be able to flow current correctly with only .35 volt drop to coil.