Burnt out coil

hi, i am trying to get to the bottom of a problem, my coil keeps burning out, its the third one now and it has burnt out agian, does anyone have any ideas to why this is happening?

Aaron

Hi
is your car running points? if so are you leaving the ignition on to possibly play a radio? this will burn out the coil

it seems to strat, and cut out quickly, tried to start it today and adjust the mixture, but started once ran for 2 mins then died when tried to start it agian. aint running anythng like radio or heater, bouth un-fused

Coil voltage suitable for 12 volts?
Alternator output at 13.8volts?