I have cable TV, and was needing to pit in an antenna so I can hopefully pick up ABC OTA. Problem is, I have 2 cables 1 from the cable and 1 from the antenna, and 1 input on the TV for these cables . How can I have an antenna and cable hooked up at once?

if your tv or cablebox doesn't accept two antenna inputs, you can get a video switcher/selector box. you'd have to manually switch it over to the desired source. they should have something like that at radioshack. tell them you have two coax antennas going into one tv and you'd like to get a source switcher/selector.

http://www.google.com/products?q=coax+video+switcher&hl=en&um=1&sa=X&oi=froogle&ct=title

Or buy a separate ATSC tuner...

I have cable TV, and was needing to pit in an antenna so I can hopefully pick up ABC OTA. Problem is, I have 2 cables 1 from the cable and 1 from the antenna, and 1 input on the TV for these cables . How can I have an antenna and cable hooked up at once?
Just wondering. Why doesn't your cable company have ABC on the channel lineup?

Just wondering. Why doesn't your cable company have ABC on the channel lineup?
A lot of cable companies don't yet provide all the HD local stations on their HD tier because the owner of the local station is asking for extra carry rights fees for the digital signal.

I have cable TV, and was needing to pit in an antenna so I can hopefully pick up ABC OTA. Problem is, I have 2 cables 1 from the cable and 1 from the antenna, and 1 input on the TV for these cables . How can I have an antenna and cable hooked up at once?
Don't you have a cable box? Without a cablecard, the TV is going to only be able to tune to the unscrambled digital QAM sub-channels, which are usually only the local stations.

A switch may not solve the problem if the TV requires a full re-scan every time you go from the cable input to a ATSC broadcast input. Some do save both sets of input, some don't. A full re-scan would make it very awkward to switch from cable to OTA. In general, they provided only 1 RF input because they figured the TV tuner would only be used for cable or broadcast TV, not both at the same time. They probably don't expect most people to even use the RF input option at all. Most people with digital cable get a cable box or buy a TV/ STB/ TivoHD which can use cable cards to get the encrypted channels.