DS3 demarc extension

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Oct 31st, 2007
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Background:

I have to extend a demarcation for a DS3 connection coming into the building over Coax. I was told to run two RG59 cables and terminate using BNC male ends.


I'm running RG59/u 20 AWG copper core at 75 ohms with 95% braid. I believe that is what I need to use for the wiring.


I was just wondering if anyone knows what the proper termination / specification is for the BNC. Do I terminate using 75 Ohm male BNC or use unrated regular BNC? I'm pretty sure I use 75 ohm termination. The telco hasn't been much help since it is my responsibility to extend the demarcation.


Any help you could provide would be greatly appreciated.

Thank you!


Correct Answer by paolo bevilacqua about 9 years 7 months ago

RG59/u is correct cabling. Which distance you have? You can also find twin micro-coax for ease on laying. The connector doesn't really matter as long good quality and the crimping job is done properly.

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Collin Clark Wed, 10/31/2007 - 10:12
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We use 75ohms too so I sure hope its right!

shaddie66 Wed, 10/31/2007 - 10:22
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Awesome. I'm glad I ordered the right thing.


Thank you for your quick response. :D

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paolo bevilacqua Wed, 10/31/2007 - 10:22
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RG59/u is correct cabling. Which distance you have? You can also find twin micro-coax for ease on laying. The connector doesn't really matter as long good quality and the crimping job is done properly.

shaddie66 Wed, 10/31/2007 - 10:44
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The distance isn't far. It just has to run from the first floor of the building to the fifth. I'd say about 100 feet vertically in the very worst case. The provisioner recommended RG59 to avoid media converters.


About the crimping difficulty-

That follows what I had read in other references.

http://www.delmar.edu/Courses/ITNW2313/icoax.htm


paolo bevilacqua Wed, 10/31/2007 - 13:45
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You should have no problems.

Thanks for the nice rating and good luck!

shaddie66 Mon, 11/05/2007 - 10:34
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This is more of a followup question that I had about BNC. I couldn't find many good resources on BNC standards :/.


I was wondering about the center pin - Obviously one side of the center pin accepts a certain AWG of wire. I was wondering about the other side. The side that pokes through the BNC and mates with the other device.


Is the size of the pin that mates with another device standardized? Basically is one side always the same "diameter"?

paolo bevilacqua Mon, 11/05/2007 - 11:15
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Yes, the center pin is standardized. What varies, is the cable or wire gauge accepted, this is declared by the manufacturer.


If all the coax stuff is driving you nuts, consider you can also use baluns (75 / 120 Ohm adapters) to carry the signal over twisted pair.

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