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HDTV Coax connection? (1 Viewer)


Jan 18, 2009
Real Name
I'm trying to figure out the best and simplest way to connect all of my devices to my TV. I'd like to make sure I get the best quality, but I also would like to avoid connecting every device directly to the TV with 3 different HDMI cables if possible.

Here is my setup:
  • Sharp Aquos HDTV
  • Comcast HD Cable Box (outputs: coax, component, DVI)
  • Panasonic HD Upconverter DVD/VHS Recorder(outputs: coax, component, HDMI)
  • Panasonic Surround Sound System (input: optical audio)

The way I have everything configured right now is:
  1. Coax Cable line from outside into my cable box
  2. From cable box, a coax line into Panasonic HD Upconverter DVD/VHS
  3. Coax from the DVD/VHS player to the TV
  4. Optical Audio on TV out to the Surround Sound unit

For connection #3, I've also tried using an HDMI cable that feeds directly from my DVD/VHS player to the TV, which I've tried using instead of a coax cable to the TV, however I haven't noticed any major difference in quality.

From the look of the picture quality I'm getting, it seems like I'm either not getting a very high quality picture from the cable company, or I've got a setup that obviously won't work when it comes to getting HD picture and sound.

What I was wondering was if someone could tell me if using coax is realistic for an HD signal. Since the HD signal has to come in using coax anyway, I don't see why it can't be used for HD picture & sound, however it looks like it can't.

Also, since I'm (apparently) doing something wrong, I was hoping someone who has a similar device setup could point me in the right direction with what I should be doing.

I've thought about using an HDMI cable for both my DVD player and my cable box, but that introduces another issue. My Surround Sound system only has one audio input. Because my cable box only has a DVI (and not HDMI) port, I have no way to send audio to my speakers from my cable box if I use a DVI/HDMI adapter (besides using component cables from the cable box to the TV I'm guessing).


Senior HTF Member
Aug 22, 2000
Real Name
See above. The coax from the cable company is compressed and modulated. Your cable box decompresses and demodulates the signal. Your cable box would need an ATSC or QAM modulator costing tens of thousands of dollars to send out HD on a coax.

There are optical switch boxes that allow two inputs to one output. Does your receiver have coaxial digital inputs? You can use an optical to coax coverter.


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