During and After the Digital Tv Transisition of June 2009.
Many Tv stations changed the channel that the station is transmitting on , WTMJ NBC is one of those Many Tv stations.
WTMJ-TV , Real UHF Digital channel 28 , virtual number (4.1) NBC.
http://en.wikipedia.org/wiki/WTMJ-TV
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It looks like there ->might be <- a Tv station transmitting on Real VHF Digital Channel 5 , virtual number (68.1)
http://en.wikipedia.org/wiki/WWAZ-TV.
However the Restrictions You have placed on antenna location and size of the antenna - Winegard HD7084P - mean that channel 5 will most likely Not be received with a antenna in the attic.
Hence the HD7696P antenna , a smaller antenna that receives channels 7 thru 51 , not 2 thru 6.
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Tvfool lists both the Real Digital Channel that is being transmitted and the virtual number in the channel list.