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Old May 15th, 2010, 06:13 AM   #1
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BNC length

I have a HDX900 and I'll be using it on a jib but I would like to mount the nanoFlash near the controls instead of on the camera and probably use a 20ft BNC, I will record on tape as well as on the nano. Is there a maximum length cable that I can safely (and successfully) use with the nanoFlash? And/or any specific recommended BNC cable/brand to minimize possible problems?

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Old May 15th, 2010, 10:12 AM   #2
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20 ft should be OK for even regular ole' single shield RG59 coax, I'd think...

I personally try to stay with RG6 for SDI applications like this however. It's a bit stiffer, but I've had interesting issues with RG59 that can result in what looks like complete signal loss if any pressure is applied to it at all...(stepping on it in the studio for instance).

In this case, it was only feeding a monitor, but i couldn't reproduce it strictly by stressing the I was spooked.

Since this is connecting to your record device, I'd go with as robust a cable as you have and test it...and have a spare ready. (the cheapest insurance you can buy, obviously)

Length-wise...20 ft really isn't much. Once we're talking about 150-200 ft with a proper spec coax cable, you may have to consider re-clocking, but 20 ft shouldn't be an issue as far as signal strength is concerned.
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Old May 15th, 2010, 11:15 PM   #3
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I did a short study on cabling with SDI as I use a multicam setup with up to 8 HD cams. The distance as somewhat limited to a 100m (300ft)
When working in standard HD (1,5GHz 1080i), if you use de solid Belden 1694A you can go up to 120 m. this cable is a bit stiffer though has great specs. If you work in 3G (1080p) you'll end up with a shorter distance. for SD you need less bandwith and then 300m (1000ft) will still work ok
For the more flexible cable we use The 1694F version which goes up to 90 mtrs. (1080i)
Also use the right connectors with gold-plated surfaces and right impedance. The Neutrik BNC's are great as it has a spindel-housing which works outstanding on patch-panels with loads of connectors next to eachother.
Here some info about the 1694F:
Using "good old RG59" is unwise as we encountered problems, even under 20 mtrs
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Old May 16th, 2010, 07:06 AM   #4
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Dear Ron,

My recommendation is to always purchase a proper spec cable.

This would be a 75 Ohm cable, with 75 ohm connectors. There are more spec's involved, but this get real technical.

We recommend Canare 75 Ohm BNC connectors. There are others that are good also.

For distances of 10 feet or more, we recommend Canare L-4CFB.

For distances of over 300 feet, we recommend Canare L-5CFB (a stiffer cable).

For under 10 feet, one can use Canare LV61s, a thinner and more flexiable cable.

We also use, successfully, a very thin cable, but we test each and every cable with very expensive test equipment.

Please note that the Canare BNC connectors are not generic, they are custom matched to the cable being used. (The parts for a BNC connector for a LV61s are different than for L-4CFB or L-5CFB.)

Please avoid 50 ohm BNC cables and connectors. These are very common, but not appropriate.

For longer distances, the cable and connectors are absolutely critical. There ae other brands and types of cables, in addition to the Canare brand items, that work.

For short distances, the cables are less critical.

As I stated above, we always recommend a proper cable. If you choose a cable that is not up to spec and report a problem, we will always suspect the cable first. HD-SDI is moderately critical in that the signal is 1.485 Gigabits per second.

In many cases, a cable that is not up to spec will cause the nanoFlash or HD-SDI monitor to not see the signal at all.

One may be able to get by with the wrong cable, and it may work, but it may cause errors
Dan Keaton
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Old May 21st, 2010, 10:08 AM   #5
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I have used various cable types successfully. On short runs, it shouldn't matter. With that said, my preferred cable for all things digital is Belden 1694a. My connector of preference is the 360 degree crimp style, which I buy from Milestek. It's much better design than the standard BNC with a great strain relief built in. I'll get a picture and post it here.

Call me and I'll hook you up if you want... since you live close by :-)

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Old May 22nd, 2010, 01:27 PM   #6
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First, I have a correction. The Belden cable I am using is 1505a. Also, I am attaching a picture of the connector I am using.

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Old May 25th, 2010, 04:06 PM   #7
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Thanks for saving my butt on the 50m ohm BNC cables, Dan.
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