You can pick up an RCA-branded balun at almost any Lowes home center. I just picked up two a week ago at my nearby store so I can check them out.
http://www.lowes.com/pd_302829-63374...d=3724168&pl=1
FWIW, it's exactly the same balun that Winegard puts on the RCA-branded stick antennas they build for Voxx and is also exactly what you'll now get if you order a Winegard TV2900 from Solid Signal.
The direct coax connection worked because it was "good enough", the typical requirement for digital reception.