In a large saucepan, combine sugar and gelatin. Stir in milk. Cook and stir over medium heat just until mixture starts to boil. Remove from heat. Whisk about 1 cup of the hot mixture into beaten eggs; return all to saucepan. Cook and stir for 2 to 3 minutes or until mixture coats the back of a clean metal spoon. Do not boil. Stir in cherries, raspberries, and orange juice concentrate. Cover and chill for 4 to 24 hours or until mixture is set.