We report on the application of a Kaufman ion source to the deposition of Nb and Ta thin films. We find that high quality Nb films (T <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">c</inf> = 9.1 K) can be produced by this technique under tolerant deposition conditions. In addition, substantial, systematic improvement in the I-V characteristics of Nb tunnel junctions has been realized by depositing, in situ, thin (≥10Å) Ta layers on the Nb film surface.