Coaxial to RCA Cable, how to? - AVS Forum
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post #1 of 15 Old 01-12-2007, 03:23 PM - Thread Starter
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Hello all-

I'm a college student, and we've got a coaxial cable (F-type connector) running to a television in our dorm room. That works great, but I've recently purchased a projector, which does not have coaxial inputs. How can we convert a coaxial cable to RCA? Here's the background:

We've purchased a TV demodulator from alltronics (search using Google, I can't post the link because < 5 posts)

This came in the other day, and I tested it out at my friends house. It didn't work very well; an image came on the screen that was clearly a television image, but it was blurry and color-distorted. He has a satellite subscription service, and I think that is the problem.

Our service in college is a subscription service, but there's no tuner box required (the coaxial comes from the wall and goes directly into the TV). I'm going back Sunday, and hope that this will work, but is there any reason it might not work? I know that descramblers are illegal, and I don't think that this demodulator functions as a descrambler.

Can anyone think of any other ideas? The projector has VGA, RCA, and S-Video inputs. I think if things really come down to the wire (i.e. Super Bowl time!) and nothing works, I can break down and buy a USB TV Tuner...any recommendations?

Thanks!
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post #2 of 15 Old 01-12-2007, 03:36 PM
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You need a cable box. You connect coaxial cable between the wallplate and the box. Then you can connect a component video (red, green and blue) cable to a component-to-VGA adapter, or use a S-video, or the yellow RCA composite port. Make sure in your projector menu all sources are enabled and you set it to auto source.

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post #3 of 15 Old 01-12-2007, 03:42 PM
 
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Quote:


This came in the other day, and I tested it out at my friends house. It didn't work very well; an image came on the screen that was clearly a television image, but it was blurry and color-distorted. He has a satellite subscription service, and I think that is the problem.

You hooked a TV tuner up to a sattelite receiver? I'm surprised you got anything at all (probably RF leaking in).
The TV tuner is for tuning and demodulating OTA or CATV ...the sat receiver is for tuning and demodulating sat signals...they're different, and not compatable.

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Then you can connect a component video (red, green and blue) cable to a component-to-VGA adapter,

There are no cheap adaptors that convert component to VGA, a transcoder is required.
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post #4 of 15 Old 01-12-2007, 04:21 PM
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You could run the co-ax into an old VHS tape recorder and the RCA output to the projector.

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post #5 of 15 Old 01-12-2007, 04:38 PM
 
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...or use the tuner he already has.
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post #6 of 15 Old 01-12-2007, 05:05 PM
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I found the spec sheet. Output is video 75 Ohm, 1 Vp-p. In other words, it's composite.

Easy fix: Get a coax cable and put an F-connector on 1 end so you can screw it into the demodulator output. Put an RCA plug on the other end. Center conductor to the pin, shielding to the shell, it should fit no problem. Plug it into the RCA input of your projector.

I'll bet that the projector RCA input jack is colored yellow, an indication that this is a composite video input.
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post #7 of 15 Old 01-12-2007, 08:07 PM - Thread Starter
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OK, thanks for the responses:

Quote:
Originally Posted by hometheaterguy View Post

You need a cable box. You connect coaxial cable between the wallplate and the box. Then you can connect a component video (red, green and blue) cable to a component-to-VGA adapter, or use a S-video, or the yellow RCA composite port. Make sure in your projector menu all sources are enabled and you set it to auto source.

The projector has a VGA-to-component adapter, so I guess this is a solution, but aren't cable boxes subscription-based? We have our cable connection as a subscription through our school, and they don't offer cable boxes specifically for this...any suggestions on where to get one if I need it?

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Originally Posted by Targus View Post

You hooked a TV tuner up to a sattelite receiver? I'm surprised you got anything at all (probably RF leaking in).
The TV tuner is for tuning and demodulating OTA or CATV ...the sat receiver is for tuning and demodulating sat signals...they're different, and not compatable.

There are no cheap adaptors that convert component to VGA, a transcoder is required.

Targus, our projector has an adapter that connects to the VGA, no transcoding required...wouldn't that work?

Also, about hooking it up to the sat receiver: I initially hooked it up straight from the wall and we got that weird crappy signal (distorted but viewable). Then I took the sat box and took the coax output from it and decided to demodulate it. Images came up very sharp, but only for a few seconds, then they disappeared.

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Originally Posted by Targus View Post

...or use the tuner he already has.

Thank you, this boosted my confidence, and I hope it works!!! The demodulator functions as a tuner, I take it?

Quote:
Originally Posted by Kevin Graf View Post

You could run the co-ax into an old VHS tape recorder and the RCA output to the projector.

I don't think this works...I've checked out the backs of most VCR's (I assume that's what you're talking about...?), and they have a separate coaxial input and output. It doesn't run it through to the RCA. Unless I'm completely off-base here? Anyone?

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Originally Posted by GeekGirl View Post

I found the spec sheet. Output is video 75 Ohm, 1 Vp-p. In other words, it's composite.

Easy fix: Get a coax cable and put an F-connector on 1 end so you can screw it into the demodulator output. Put an RCA plug on the other end. Center conductor to the pin, shielding to the shell, it should fit no problem. Plug it into the RCA input of your projector.

I'll bet that the projector RCA input jack is colored yellow, an indication that this is a composite video input.

Are you sure that will work? Doesn't coax carry both audio and video on one signal? How can I get the audio off of the signal? The way you described it, I would essentially take an F-type and convert it to a single RCA...but that leaves me without audio.
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post #8 of 15 Old 01-13-2007, 07:03 AM
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The co-ax from the cable company has TV channels #2 and up (it may also have the new digital channels, these maybe encoded and only available through the newest cable company Set Top Box "STB").
The VCR tunes to a channel and the RCA outputs are Video and Audio (of that one channel).

Kevin
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post #9 of 15 Old 01-13-2007, 07:10 AM
 
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Unless I'm completely off-base here? Anyone?

Yes, every VCR built since 1982 has a tuner/demodulator built into it, which outputs signals as composite video, line level audio, as well as modulated RF.

BTW, a TV tuner, without a demodulator, is useless.
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post #10 of 15 Old 01-13-2007, 07:18 AM - Thread Starter
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Quote:
Originally Posted by Kevin Graf View Post

The co-ax from the cable company has TV channels #2 and up (it may also have the new digital channels, these maybe encoded and only available through the newest cable company Set Top Box "STB").
The VCR tunes to a channel and the RCA outputs are Video and Audio (of that one channel).

Quote:
Originally Posted by Targus View Post

Yes, every VCR built since 1982 has a tuner/demodulator built into it, which outputs signals as composite video, line level audio, as well as modulated RF.

BTW, a TV tuner, without a demodulator, is useless.

Thanks to the both of you! We can use this if our current demodulator doesn't work.
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post #11 of 15 Old 01-13-2007, 09:34 AM
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Quote:
Originally Posted by Rockmaninoff View Post

Thanks to the both of you! We can use this if our current demodulator doesn't work.



How to hook up a VCR to the projector:

Cable TV Coax from the wall outlet would go to the INPUT on the VCR.

Locate the YELLOW, WHITE, and RED OUTPUT jacks on VCR and use RCA cables to hook up to projector. On the projector there should be an input select to choose the composite (yellow, white, red) jacks as the video display.

You would change channels (or watch VHS movies) with the VCR's remote or front panel buttons. Not all VCR's are stereo, so you might only have a yellow and white wire. This will still work, but with one audio speaker instead of two.
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post #12 of 15 Old 01-14-2007, 11:59 AM
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Just remember the component-to-VGA adapter will give you a better picture then the yellow RCA composite interconnection.

Also, audio through a projector is the minority (for home theater). The small speakers in projectors are used as a one time cue for presentation for hotels, etc. In big home theater all audio will be amplified from a prepro, AVR, separate power amps, etc. to the speakers.

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post #13 of 15 Old 01-15-2007, 12:04 PM
 
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Just remember the component-to-VGA adapter will give you a better picture then the yellow RCA composite interconnection.

What NTSC tuner has component outputs? Why would it, when the signal delivered to it is composite anyway?
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post #14 of 15 Old 01-17-2007, 07:34 PM
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Some NTSC tuners today now have component outputs:

http://www.crutchfield.com/S-ccadXmv...p?i=305SIRT165

http://search.yahoo.com/search?p=Wha...p=mss&ei=UTF-8

With a front projector and one of these tuners you can get this component connection.

A veteran is someone who, wrote a blank check Made Payable to 'The USA, ' for an amount of 'up to and including their life.'
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post #15 of 15 Old 01-18-2007, 07:31 AM
 
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notice how they all include ATSC tuners as well?
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