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HD SDI Cable Specifications


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#1 Brandon Whiteside

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Posted 17 March 2012 - 02:23 AM

Hey everyone,

Im trying to find out if there is a specific grade of cable and BNC connector that is used for HD SDI cables.

Here is my latest project: I am flying a cinema products sk (I know everyone hates it but I have retrofitted a Marshall 7" to it with 15mm rods and it will fly a red one, so it currently works for me) and I want to re cable it for HD SDI. It has a BNC on the sled and a lemo where the post connects to the base.

Anyway, let me know if you may have any pointers or tips.

Thanks
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#2 William Demeritt

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Posted 17 March 2012 - 02:00 PM

I believe the universal characteristic of all HD-SDI cables is 75 ohm resistance. The other characteristics give varied results. I prefer Belden 1505 and Belden 1694a for HD-SDI, although 1694 is solid copper (not stranded), so not ideal if it's in a post that collapses and expands. VERY STIFF. 1505 might be your best bet?
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#3 Brandon Whiteside

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Posted 17 March 2012 - 04:40 PM

Stranded would definitely be better...at least for soldering. I will look into it and report back as soon as I make it happen. Thanks!
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#4 William Demeritt

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Posted 17 March 2012 - 06:34 PM

I may be wrong, but I'm pretty sure HD-SDI requires crimping BNC connectors and bulkheads, not solder BNC. However, yea, stranded is easier to work with, but you require a lower AWG to match the transmission capability of a higher AWG solid copper core.
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#5 Louis Puli SOC

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Posted 17 March 2012 - 06:36 PM

"Anyway, let me know if you may have any pointers or tips."

Hi Brandon
I am looking at upgrading to HD as well .I am looking at this cable Belden179DT SDI/HDTVRG179 .

http://www.sjmediasy...79dt-b-b-6.html
I will let you know how I go .
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#6 Afton Grant

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Posted 17 March 2012 - 10:10 PM

I may be wrong, but I'm pretty sure HD-SDI requires crimping BNC connectors and bulkheads, not solder BNC. However, yea, stranded is easier to work with, but you require a lower AWG to match the transmission capability of a higher AWG solid copper core.


I solder all my HD BNC cables. Never had a problem. Why would that make any difference....especially a negative one?
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#7 Eric Fletcher S.O.C.

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Posted 17 March 2012 - 10:33 PM

I may be wrong, but I'm pretty sure HD-SDI requires crimping BNC connectors and bulkheads, not solder BNC. However, yea, stranded is easier to work with, but you require a lower AWG to match the transmission capability of a higher AWG solid copper core.


I solder all my HD BNC cables. Never had a problem. Why would that make any difference....especially a negative one?



Crimping actually is the preferred method since it's a mechanical connection
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#8 John Saunders

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Posted 17 March 2012 - 10:47 PM

If you like 1694A they also make a flexible version that is really nice and has a stranded core. It's 1694F and is pretty pricey but great cable. I have a spool of it if anyone wants to try it or needs a cable made. It's pretty big cable though and may not be the best for a center post cable. We always crimp our cables for what it's worth. I think the main thing is that you make sure you are using 75 ohm connectors and cable that is rated for at least 1.5 ghz bandwidth. Hope it helps.
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#9 John Saunders

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Posted 17 March 2012 - 10:52 PM

Oh and for small hd sdi cable we use 1855a. I think it is still a solid core but due to its smaller size it is pretty flexible. Also if you are going to solder it to a lemo it would be much easier than 1694F.
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#10 Brandon Whiteside

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Posted 18 March 2012 - 01:56 AM

Wow thank you for all of the replies. I'll do my research and report back. John, are you in LA?
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#11 Afton Grant

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Posted 18 March 2012 - 05:22 AM

Crimping actually is the preferred method since it's a mechanical connection


Guess I'm just curious at this point. My background in engineering consists of a couple books on my shelf that I pretend to have read. Why is a mechanical connection better than one where the two conductors are, for lack of a better term, fused together with metal? It's just counter intuitive if that's the case.
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#12 John Saunders

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Posted 18 March 2012 - 07:51 AM

Wow thank you for all of the replies. I'll do my research and report back. John, are you in LA?

No I'm on the east coast in MD. If you want a couple feet of cable just let me know I can send you some, I know it can be a pain to get small quantities of it. I can also throw some bncs on it for a few bucks.
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#13 John Saunders

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Posted 18 March 2012 - 08:00 AM

Crimping actually is the preferred method since it's a mechanical connection


Guess I'm just curious at this point. My background in engineering consists of a couple books on my shelf that I pretend to have read. Why is a mechanical connection better than one where the two conductors are, for lack of a better term, fused together with metal? It's just counter intuitive if that's the case.


I'm not an engineer either although I have been making cable my whole life. The only thing I can think of about soldiering bncs is that it might change the resistance of the connection thus affecting the 75 ohm rating. Not sure though and I do know that a properly soldiered connection is normally stronger than a crimped on. I am not sure how you soldier the sleeve though seems like it would be tough.

I do like soldiering me some cables though:)

Heres the last big panel I worked on:

80 something pairs of audio
2 snakes
2 multipins
24 paralleled xlr connectors

Loads of fun....

Attached Files


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#14 Afton Grant

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Posted 18 March 2012 - 10:01 AM

I'm not an engineer either although I have been making cable my whole life. The only thing I can think of about soldiering bncs is that it might change the resistance of the connection thus affecting the 75 ohm rating. Not sure though and I do know that a properly soldiered connection is normally stronger than a crimped on. I am not sure how you soldier the sleeve though seems like it would be tough.


But any contact between two conductors affects the overall resistance slightly. Again, it's just intuitive to think that a connection made by heat and melting metal would make for less resistance than a connection made by only pressure. Otherwise, why are so many other connections in electronics (wires, circuit boards, components) soldered rather than plugged or crimped?

I actually don't solder the sleeve. I use epoxy and shrink tubing to hold things in place.
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#15 John Saunders

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Posted 18 March 2012 - 10:12 AM

I'm not an engineer either although I have been making cable my whole life. The only thing I can think of about soldiering bncs is that it might change the resistance of the connection thus affecting the 75 ohm rating. Not sure though and I do know that a properly soldiered connection is normally stronger than a crimped on. I am not sure how you soldier the sleeve though seems like it would be tough.


But any contact between two conductors affects the overall resistance slightly. Again, it's just intuitive to think that a connection made by heat and melting metal would make for less resistance than a connection made by only pressure. Otherwise, why are so many other connections in electronics (wires, circuit boards, components) soldered rather than plugged or crimped?

I actually don't solder the sleeve. I use epoxy and shrink tubing to hold things in place.

If it works for you thats all that matters I guess. To each his own.

Seems like more work than just crimping it, but the tooling can be a little bit of an investment at first.
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