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Discussion Starter · #1 ·
I'd like to run DVI-D in-wall. From research so far, it seems that DVI-D cables are limited about 5m, although one vendor claims their product will handle 9m. So, I'm wondering...


Can I breakout DVI-D to 75 ohm coax, say RG-6? In other words, run multiple lengths of RG-6 in the walls, and terminate at each end with BNC connectors. Then, use DVI-D to BNC breakout interconnect between wall plates and equipment.


How many RG-6 cables would be required for DVI-D connection? Is DVI-D compatible with 75 ohm coax?


Is there a beter way to achieve > 5m in-wall runs?


Regards,


DG
 

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Discussion Starter · #3 ·
Thank you, tvtech1, for that valuable information.


What is characteristic impedance of cat5e. With 4 pairs per cable, I could use 2 or 3, or however many necessary to handle the number of pairs in DVI-D.


If cat5 is not satisfactory, is there any commonly available bulk twisted pair cable that I could use?


What about other kinds of coax? Is there any 110 Ohm? Could I make double runs of suitable(?) coax for the differential pairs?


What would the "real" solution for runing DVI-D for lengths > 15 ft., and in-wall?


How are others making longer DVI-D runs?


Thank you.


DG
 

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CAT 5 cable is 100 ohm resistance.


I believe that the 110 ohm twisted pair cable is what is commonly used in microphone cable and the 'snake' cables that are used in studios to bring the signals into the mixing board. You might be able to find bulk multiconductor snake cable to handle your DVI signal.
 

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The characteristic IMPEDANCE of CAt V is 100 Ohms...more or less, depending on which pair you're measuring.

Quote:
I believe that the 110 ohm twisted pair cable is what is commonly used in microphone cable and the 'snake' cables that are used in studios to bring the signals into the mixing board.
No, 110 Ohm twisted pairs are used for AES/EBU digital audio. Not analog audio, which is what an audio 'snake' would carry, if carrying mic signals.


Belden 1800 B is a 110 Ohm STP. others make it as well.


Will this work for DVI-D? I doubt it, but give it a try.
 

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Discussion Starter · #6 ·
Thank you.


tvtech1, might you be able to expand on your comment about doubt regarding Belden 1800B? Is matching the characteristic impedance insufficient? Is termination the issue? (Getting proper connectors, and being able to attach them?) Or something else? Certainly bandwidth of the cable wouldn't be an issue, right?


Has anyone run >15' length of DVI-D or DVI-I?


Regards,


DG
 

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Having read many posts on DVI-D cables, simply running longer spans and introducing cable connectors, to get back to the appropriate pin-out will change the impedance of the overall cable. Introducing sparklies to your image.


Depending on the length of the cable run it would be best to contact Lindy cable they make custom cables at some great prices, and will advise you as to maximum lengths. I suspect that if you need to get longer than 10 Meters you will need to go fiber. At which point the cables themselves start at around $600.00 USD.


It almost doesn't make sense to make your own cable unless you can get the cabling for free at which point it simply becomes a logistic question. As to whether or not you will be able to meet the specifications using what you have available.

http://www.techreactions.com/Lindy%20DVI%20Cable/


Good Luck,


Cheers,


Requis
 

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Discussion Starter · #9 ·
tvtech1,


Quote:
The cable capacitance would be an issue for DVI-D signals.


It's been a long time, so I'm very uncertain of this stuff, and you seem much more familiar and current... but, isn't characteristic impedance a function of the (distributed) capacitance? So, wouldn't getting the characteristic impedance correct mean the capacitance would be right?


DG
 

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Quote:
So, wouldn't getting the characteristic impedance correct mean the capacitance would be right?
Not necessarily. The impedance is determined by the capacitance, inductance and resistance. You could have a highly capacitive cable, low inductance, and still have a 110 Ohm impedance.

The cable I quoted is meant for digital audio, which has a much lower 'data rate' (frequency) then DVI-D.
 

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Quote:
Originally posted by tvtech1
"Is matching the characteristic impedance insufficient? "


The cable capacitance would be an issue for DVI-D signals.
I can only answer in Laymans experiences and not with any technical back-ground. Other than perhaps alot of reading and research on the subject.


I have seen a home made DVI-D cable longer than 10 meters, it was not what I would term functional as it introduced sparklies in the image and other anomolies. The cable was copper, and was made of two 10 meter length cables with an adapter in the middle. The overall image was functional but you could definitely tell the difference once you took out a cable run and plugged directly.


Sorry I can't get into a Technical discussion on the strengths / failings of DVI-D, But I am sure there are others that may be able to help you.


Cheers,


Requis


Its all about fun!
 
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