Marlin, I don' tknow the specs on the 293 coil, but the "blaster" coils are internally designed to not use a ballast. IF there is a ballast in the original wiring,it needs to be jumped.
Most hi-perf factory coils came with a ballast resistor in the circuit from the switch to the Pos. terminal of the coil. When the switch is in the Start position, the ballast is by-passed by the wiring in the harness so the coil gets a full 12V on the primary. When the switch is in the Run position (or ON pos.), the feed is through the ballast and lowers the voltage across the points to about 3-4 volts which saves point life. That's the purpose of it. IF you use a coil that was designed to use a ballast and it shorts or is by-passed, it will cook the coil. I hope that explanation made sense.
Verne
Also, a lot of cars use a resistance wire rather than an external ballast resistor. In that case, there are 2 wires going to the Pos side of the coil. One is the white braided resistance wire and the colored wire supplies the full 12V for Start. In the On position, a lowered voltage is supplied to the coil through a resistance wire.