Analog Food Network was just shut down so we installed the new little boxes that comcast sent. The picture quality is horrible on our high-def TV. There is a computer connected to the TV and the cable picture is as bad as youtube. Those DirectTV commercials where they say they have the most HD have me thinking.
My question is how do I bypass the box for PBS HD, NBC HD, etc? I think if I put in a splitter and an A-B switch, I will have 2 problems. In addition to being operationally annoying, the signal will be too weak for ABC HD (which was the strongest a couple years ago, but is the weakest now). Has anyone put in an A-B switch? Does Comcast provide these. This has been the biggest downgrade in a long-time, but I don't want to pay $8 a month for free HD plus there is no place for a giant box near this TV. In a couple of years Sprint will have TV on WiMax and this will all be over. With AT&T (coming soon), ComCast and Sprint competing for my business, I will actually be able to get HD without an ugly dish on my roof!
Another alternative is to use an RF DEmodulator after the DTA. That will let you send the DTA's output to an AV input instead of using an A/B switch. Stand-alone demodulators are around $55-60. If you have an old VCR, you could use it as a demodulator. Just set it to channel 3, and connect the AV outputs to your TV's AV inputs.
Some Comcast office seem to have A/B switch kits, but not in all regions. I have stopped by multiple offices in my area, and Comcast doesn't have them, agents said go to Radio Shack, or a store of your choice.
If your home is wired properly, you shouldn't have issues adding one one splitter behind a TV, but not all homes are wired properly, then they have signal issues, especially at the higher frequencies digital signal are carried on.
If you really want the best experience, you should upgrade to a HD set top box. You have a large investment in your HDTV and should enjoy it.