CFL you mean? You can probably hook up the ballast to a T5 tube of similar wattage to the original, dead tube. If it's a 20W ballast and a 15w tube, it might run the tube at 15W and it might run it at 20W. Either would be ok, but just be aware that you could be running the tube out of spec. The ballast isn't worth much though. New CFLs are as cheap as $1-2 each.
