Preheat the oven to 350 degrees F (175 degrees C). Grease a 9x5 inch loaf pan. I use a glass one.
In a medium bowl, cream together the butter and sugar until smooth. Beat in the eggs one at a time, then stir in the sour cream. Sift together the flour, baking soda, cream of tartar and salt; stir into the sour cream mixture until just blended. Fold in raisins. Transfer the batter to the prepared loaf pan.
Bake for 50 to 60 minutes in the preheated oven, or until a small knife inserted into the crown, comes out clean.