I found this reply here:
My husband had our american TV shipped over to Australia, thinking that it should work if we subscribe to Foxtel or anything with a digital signal. As a previous poster has written, this is certainly NOT the case.
We are unable to get Foxtel, free to air TV, satellite tv, our Australian PSP doesn't work, Nintento etc bought in Australia doesn't work ... the long and short of it is that we have a 50 inch glorified DVD (American ONLY) player. It's utterly useless.
Another idea to view broadcast TV is to get an external antenna to HDMI box (such as this) in Australia and then plug it into our TV. Would this work? I assume that the HDMI standard is universal. If we used a transformer to get 120V/50hz, I wonder if the TV would work on that lower frequency? Not sure if electronic converters would have a smooth enough waveform, or enough power (300W). I assume that the refresh rate is generated internally, not from the mains supply.