Dear Mr. Berko: Every three months, I receive patent royalties. Last year, I received $3,877, $3,206, $2,135 and $3,440. I’ve had to buy low-paying certificates of deposit because the minimum corporate bond purchase is $5,000 and I never seem to get that much at one time. Now I have 14 different CDs paying between 1.1 percent and 2.3 percent. I know I could get 4 to 6 percent with good common stocks, but I don’t want to own stocks because they are so unpredictable.