# Is there any HDMI to COAX converters in the market?



## philmalik

I did a search a while ago, and a company called Gefen apparently has a HDMI to coax "extender" (their words) which was supposed to be on the market earlier this year.

Just wondering if anyone has installed/used any brand of an HDMI to coax converter and any success stories?

thanks in advance

Mods, feel free to move this thread to another forum topic if needed.


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## Stuart Sweet

Moved to the Broadcast/HDTV forum.


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## Doug Brott

philmalik,

How far are you trying to extend?


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## philmalik

Doug Brott said:


> philmalik,
> 
> How far are you trying to extend?


We need to go from the downstairs rec room to the upstairs TV. I'm guessing 100 to 150 feet. (or more).

It's already prewired for coax, and right now I'm sending the signal from my Hr20-700 to my VCR via RCA jacks, then out from the VCR via coax up through the house, up to another VCR, and out the VCR via RCA jacks to the TV upstairs.

I have no plans on buying another receiver as I only watch either the TV upstairs or downstairs TV but not both at the same time.

And with the IR remote from the HR20-700 I can operate it from wherever in the house.

I would just like to get an HD feed up to my HD TV in the kitchen.

thanks


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## Tom Robertson

I have used the OWLink HDMI over fibre optic, works great! 

Cheers,
Tom


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## philmalik

I was hoping to use the existing coax cable that's already wired in the wall.



Tom Robertson said:


> I have used the OWLink HDMI over fibre optic, works great!
> 
> Cheers,
> Tom


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## sheltrk

Looks to me like the Gefen "HDMI over RGB" extender is currently available for pre-order @$499 a pop: http://www.gefen.com/kvm/dproduct.jsp?prod_id=5304

So yes, you could extend your HDMI run this way, but you need a minimum of 4 coax cables to do it, at least with the Gefen offering...


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## Grentz

The problem is coax only has 2 leads, so anything has to be converted to run over 2 leads to run with a single coax. That is why the gefen requires 4 coax cables (8 leads)


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## brant

philmalik said:


> I did a search a while ago, and a company called Gefen apparently has a HDMI to coax "extender" (their words) which was supposed to be on the market earlier this year.
> 
> Just wondering if anyone has installed/used any brand of an HDMI to coax converter and any success stories?
> 
> thanks in advance
> 
> Mods, feel free to move this thread to another forum topic if needed.


Probably not, because it wouldn't work over 1 coax cable. Can you use the existing coax to fish cat5 through the wall?


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## brant

Grentz said:


> The problem is coax only has 2 leads, so anything has to be converted to run over 2 leads to run with a single coax. That is why the gefen requires 4 coax cables (8 leads)


huh? coax has one conductor and a shield.

that geffen unit uses RGBHV cabling.


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## Grentz

brant said:


> huh? coax has one conductor and a shield.
> 
> that geffen unit uses RGBHV cabling.


You can use the shield as a lead though, that is what many of the rca -> coax baluns do.


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## brant

Grentz said:


> You can use the shield as a lead though, that is what many of the rca -> coax baluns do.


i can positively say i've never seen a device that does that. who makes such a thing? RCA type cable _is_ coaxial cable, so I'm not sure of the purpose of the balun. You're going to have to show me how that possibly works (using shield to transmit sound/video). UTP cable is what you use for RCA baluns, or just run coax and compress an RCA connector on the end of it.

______________________________________________________________
One thing I want to make sure you guys are clear on that geffen product before you buy it, RGBHV cables do not transmit sound. Only R, G, B, horiz & vert sync.


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## Stuart Sweet

I remember being told that there was a standard for high-bandwidth over RG6 cable that was being used for broadcast centers but it was rejected because it contained no copy protection. If you think about it, given the amount of data that travels from the satellite to the TV there's clearly enough bandwidth over a single RG6 run to support a single 19.2 megabit stream. The problem is more legal than technical... making sure that the HDMI handshaking was taking place in a way that satisfied the sending unit.


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## TomCat

brant said:


> RCA type cable _is_ coaxial cable, so I'm not sure of the purpose of the balun...


It is indeed coaxial, but it is not equivalent to coax such as that designed to transport RF. RG-6, for instance, has a characteristic impedance of 75 ohms, which means that to an RF signal it appears as an infinite piece of waveguide tuned to and capable of carrying high frequencies at low loss. Baseband signals, on the other hand, such as analog audio and video which exist at much lower frequencies do not need to use the same technology, and can be transported through coax that basically just makes a physical connection (and does not need to work at higher frequencies) not much different than the same way DC or AC power is transported.

"Balun" is short for "balanced-unbalanced" and typically refers to an impedance-matching transformer, such as the kind that can convert 300-ohm twinlead to 75-ohm coax, or to an audio transformer that can convert low-Z balanced signals to high-Z unbalanced (or vice versa). If you were converting an unbalanced signal to balanced to provide interference-rejection capability, a balun would be in order. That is probably a similar reason to why a balun might be needed in the instance you refer to.


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## Grentz

brant said:


> i can positively say i've never seen a device that does that. who makes such a thing? RCA type cable _is_ coaxial cable, so I'm not sure of the purpose of the balun. You're going to have to show me how that possibly works (using shield to transmit sound/video). UTP cable is what you use for RCA baluns, or just run coax and compress an RCA connector on the end of it.
> 
> ______________________________________________________________
> One thing I want to make sure you guys are clear on that geffen product before you buy it, RGBHV cables do not transmit sound. Only R, G, B, horiz & vert sync.


I have some old low voltage IR/Video sender stuff that uses the coax as two leads.

You can also try it yourself, I hacked together some adapters that allow you to run two leads through a coax cable. The center pin is one, and the outer screw (or shield) is the other.

Not say it is ideal, but it works.


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## brant

TomCat said:


> It is indeed coaxial, but it is not equivalent to coax such as that designed to transport RF.


my point is that you can run composite through the existing coax, if you had enough lines. it was my interpretation that the poster was saying the HDMI-RGBHV converter would use the shield as a conductor to transmit the signal; that is not true. that converter would be used to change an a projector w/ RGBHV inputs to one w/ HDMI inputs; no sound.

using the shield as a conductor sounds like a terrible idea.


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## afitch99

Run Cat5.

Remember you need 2 Cat5 runs to use HDMI Balun's.


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