The authors have used RF magnetron sputtering from a large near-stoichiometric YBCO target onto heated substrates to produce c-axis oriented films with Tc=87 K in situ, without a subsequent post-anneal. Effects of negative ion bombardment were avoided by placing substrates above the center of the target, directly above a grounded ion shield. Film properties are rather sensitive to small changes in target composition. At 66 K, critical currents of optimum films are greater than 1MA/cm2, and microwave surface resistance at 2 GHz is less than 10 m Omega .