Superconducting Y-Ba-Cu-O films have been successfully grown on 2-in.-diam (100) MgO and CeO2-buffered R-plane sapphire substrates using a simple, inexpensive hot-wall dc sputtering system. The deposition chamber was made of a quartz tube and heated by a furnace outside the chamber. A new sputter gun was developed by shielding the surface of a cathode electrode using an insulating layer of alumina. The spatial variations of thickness and composition of films across a 2-in.-diam wafer are 4.9% and 4.2%, respectively. Superconducting properties of the films within a 2-in.-diam area are zero-resistance temperature Tc (zero) of 88-90 K and critical current density Jc (77 K, zero field) of (1.5-3.5) X 10(6) A/cm(2).