I actually found the answer to my question elsewhere. The digital tuners in the market only support
ATSC tuning. To get digital channels above 69 a QAM tuner is required.
Due to the shortsightedness of the US govt the requirement for
digital transition is to only support
ATSC tuner. Hence this is what all the digital tuners in the market are supporting.
Most
HDTV's come with
ATSC, QAM and
NTSC tuners.