Combine orange rind and 1 cup water in container of an electric blender; process until finely chopped. Pour mixture into a small non-aluminum saucepan; add soda, stirring well. Bring to a boil. Reduce heat; cover and simmer 5 minutes. Rinse and drain.
Return orange rind to saucepan; add remaining water. Bring to a boil. Reduce heat; cover and simmer 5 minutes. Set aside to cool.
Combine grapefruit pulp, orange pulp, cranberries, and reserved rind mixture in a flat-bottomed kettle. Bring to a boil; boil 15 minutes, stirring frequently. Stir in sugar, and boil until mixture reaches 220° on a candy thermometer or until mixture sheets from a cold metal spoon. Add pecans and raisins, stirring well. Remove from heat, and skim off foam with a metal spoon.
Quickly ladle conserve into hot sterilized jars, leaving 1/4- inch head space. Cover at once with metal lids, and screw bands tight. Process in boiling water bath 10 minutes.