HD SDI Cable Specifications

[Mike Germond SOC]

I use RG-179 for my HD post cable and lightweight jumpers. It is 75ohm and uses compression fittings on the ends (the center pin gets soldered though). It's the same stuff Tiffen (and probably other brands) use inside their sleds for HD-SDI wiring. I can get the stuff pretty cheap and by the foot locally if anyone ever needs some (ends too). Here's the quickest examples that I could find:

 

RG179:

 

Clamp/Solder style 75ohm connectors for RG179:

Edited March 18, 2012 by Mike Germond

[Phil Thomas]

Hi

 

I may be completely shown up by someone with more electronics knowledge than me here but I believe any 75 ohm co-axial cable with BNC connectors will work for HD-SDI, especially over short distances (length of a sled) just don't try to T-piece it to split it or anything like that. The more superior cable types will just allow the signal to travel along longer cable runs without breaking down. And because its a digital signal it either works perfectly or not at all. If you can get some cable locally (and relatively cheaply) try using 3 or 4 times the length that you actually need soldered (or whatever) with the BNCs like you would when you build it properly inside your rig and test it from a source and your monitor. If the signal gets there your on to a winner and you have some redundancy by knowing that it could travel 4 times further and your not just under the limit of breakdown.

 

I have heard though (don't know how true it is) that REDs are wired badly inside so if you plug into more than 1 of HD-SDI outputs (monitor/recorder/transmitter) it weakens the output strength of each signal causing breakdown on shorter cable lengths (sometimes as short as a steadicam sled).

 

I have also heard (from someone else) that the power running around inside a steadicam post can cause interference in HD-SDI cores making it breakdown also. Not sure on the solution for this one, probably more of a problem when using all the cables grouped together, rather than a single cable you've put in yourself separately.

 

Phil

[Jess Haas SOC]

I have rg179 inside my sled. Taped it to the origional coily cable so that everything telescopes fine and soldered it to the sleds origional non HD speced BNCs. I chopped a cable to do it and put a barrel in the middle so that I can disassemble the sled. All those connections arent ideal but the only time I have ever had any dropouts is with the Red which puts out a weak HD-SDI signal. Even then it didnt cause any problems so I still haven't bothered replacing the barrel with the female BNC connector I have sitting on my desk.

 

-Jess

[Hugo_Langer]

I thought I might chime in here...

 

Terry West in California has some of our Steadicam looms in stock.

 

These looms have been manufactured with RG-179 (braided core) to carry HD-SDI.

 

They have been purpose made to suit Steadicam centre posts and others, they have a coiled centre section with a one metre tail on each end (for trimming).

 

Terry can be reached at

 

Terry West

Redondo Beach, CA

Business Phone 310 374 5711

Mobile Phone 310 621 5063

[Leandro Silva]

Hello everyone. Also considering an HD upgrade. Just wondering what is the best way to do it... I may try to do it locally so I can minimize the down time. Is it better to connect the cables to the bnc Plugs directly, or is it better to hack it to the original coiler cable socket?

 

Thanks.

 

Leandro Silva

[joe mcnally]

Hi Brandon

so as far as I understand and from experience the crimped joint is less prone to breakdown than solder.

Solder can and does easily crack and fail when stresssed mechanically.

A good crimped joint can be twisted and turned a lot before breakdown of course it assumes a good crimp in the first place.

Also, in theory, the digital signal should be all or nothing but Ive found in practice there a a few irritations that can happen before total loss of signal. Sparkling on longer lengths. Tearing of the picture as the signal gets weaker. Loss of high frequencies (detail)

All best

Joe

[Colin Donahue]

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

Afton Grant

 

 

Afton, I know this is a year old, but I just rewired my sled and it was an ordeal. My original plan was to solder all connections, but

I was having trouble with the connections not working properly. I took it to Tiffen and they pointed out that the core of my RG 178 cable had about 3/8 of an inch exposed and unshielded where it was soldered to the BNC connector.. They said unshielded should be 1/8 inch or less. This makes for a little more difficult soldering for me. I then decided that I wanted some flexibility if i took it apart so I went with SMS connectors threaded on to a BNC. Used RG178 cable.This presented more problems because I needed two crimpers, for the sms connectors. and one of them cost $800. I ended up running all the wires myself, then had Tiffen put the connectors on and crimp them. It was about $95

 

Colin Donahue

[Peter Abraham]

Unsheilded areas can be managed with my new favorite material: Liquid Electrical Tape.

 

Peter Abraham, S.O.C.

[Noel Sterrett]

 

so as far as I understand and from experience the crimped joint is less prone to breakdown than solder.

 

 

 

I've been soldering coax since I was 10 (a very long time ago) and I must say my experience is the opposite. I've never felt comfortable with a crimp. With solder, you can see when you have a good, shiny (not cold) solder connection. With crimps, you have to pull hard to test them. When you do, they just pull out far too often.

 

Cheers.

[Peter Abraham]

Funny you mention this. I do both. Seriously.

 

I have spent a fair bit of time recently using my new BNC Crimp tool on the Zalex™ Tally HR lights I make and sell for rigs. There's a tiny hole in every center pin on a BNC crimp assembly. I strip, mount the pin and turn to have the hole facing up. I run a tiny bit of solder into the hole. Then I crimp.

 

Pretty hard to tug it out- though of course I guess one could- once the braiding within the center pin has been surrounded with solder, then crimped hard into place.

 

Worth the extra 2 minutes per cable to know it would take an immense yank to remove it.

 

Best to all,

 

Peter Abraham, S.O.C.

[Noel Sterrett]

Funny you mention this. I do both. Seriously.

 

I have spent a fair bit of time recently using my new BNC Crimp tool on the Zalex™ Tally HR lights I make and sell for rigs. There's a tiny hole in every center pin on a BNC crimp assembly. I strip, mount the pin and turn to have the hole facing up. I run a tiny bit of solder into the hole. Then I crimp.

 

Both is generally best.

 

For Lemo's, there are actually two versions: crimp and solder. I considered using crimp because the pins are so small they are nearly impossible to solder, but as I recall the crimp tool cost almost as much as my rig.

 

Cheers.

[Chris Callarman]

So what I take from this thread is that stranded cable is prefered. Belden 1505 and 1694 have been mentioned but both seem a bit thick for a telescoping center post. Any suggestions for a thin stranded cable? I'm guessing something the size of mini RG59 or smaller would be best.

[omsteadica]

i am looking marshall or any SDI HD moniter 7inch.