Dear Mr. Berko: Please explain convertible bonds. We're in our late 50s. We are not aggressive investors and own a $310,000 portfolio of stocks – mostly utilities and other income stocks – yielding 3 to 9 percent. A stockbroker tried to explain convertible bonds to us, but she just made it more confusing. Could you give us a simple explanation so we can have a clearer understanding? And could you recommend some convertible mutual funds to buy? We have about $21,000 to invest. – PB, Waterloo, Iowa