Cream butter; gradually add sugar, beating well. Add eggs, one at a time, beating well after each addition. Add sweet potatoes; beat well.
Combine flour, baking powder, soda, cinnamon, nutmeg, and salt; gradually add to sweet potato mixture, beating well after each addition (batter will be stiff). Stir in vanilla, coconut, and pecans.
Spoon batter into a well - greased 10-inch tube pan. Bake at 350° for 1 hour and 15 minutes or until cake tests done. Cool in pan 15 minutes; remove from pan, and let cool completely.
Note: Sweet Potato Pound Cake may be glazed or frosted with any lemon- or orange-flavored topping.