View Full Version : Running a split composite video signal 400 feet

08-19-2013, 07:14 PM
Camera: Sony HDR CX-190
Video Out: Composite

I am trying to send a split video composite signal approximately 400' (from behind goal posts up to a high school's press box) and into a Tricaster STUDIO.

Why split the signal? Because I'm trying to tap off a camera that sits 30' above the ground on a Hi-Pad.

I AM able to send an un-split video composite signal 500' through a video balun/CAT5 configuration (though not as well through 500' of RG59 coax). But when I connect the same 500' cable (both configs) through a splitter, the video gets very ghosty.

I've tried a distribution amplifier but that did not help.

Thank you, in advance, for your questions and possible solutions.

08-19-2013, 09:46 PM
I would first recommend using the Distribution Amplifier. One question about it. Is it a new unit or one that has been sitting around for many years? I've found that most analog distributions amplifiers output drift over time, they usually have a pot on them for adjustment, if this unit is many years old, it might need to adjusted so it is outputting the correct level.

The next issue is the type of cable you are using. RG59 is not as good for long cable runs, you might want to look at using RG6 (or maybe even RG11) for these longer runs.

08-19-2013, 11:42 PM
The Distribution Amplifier was new. Adjusting the output only made the video image more "wavy." I've since returned the Distribution Amp but can get another one based on your recommendation.

As far using RG59, I had read elsewhere on the internet: "For short cable runs, use RG59/U with a 22-gauge center conductor, which has a DC resistance of about 16 ohms per 1,000 feet (304 m). For longer runs, the 20-gauge variety which has a DC resistance of approximately 10 ohms per 1,000 feet will work well. In either case, cables with polyurethane or polyethylene as the dielectric material are readily available. For installations requiring cable runs between 800 (244 m) and 1,500 feet (457 m),RG6/U is best."

When I bought the RG59, I made sure I bought 20-gauge, pure copper coax. (I cut, stripped, terminated and compressed coax ends myself. Wonder if there's leakage??) I could try RG6, get a new distribution amp, or, get a $1000 line-of-sight wireless video transmitter.


08-20-2013, 12:30 AM
have you checked if Termination is an issue? Or tried a "hummbucker"?

08-20-2013, 01:02 AM
@Dexter2999: What does Termination mean? What's a hummbucker?

08-20-2013, 07:17 AM

That link is to an overall on issues with running signal.

Termination is (for a non-technical explanation) when a piece of gear is expecting a signal to pass through so it leaves the path open. A terminator closes that path. What is technically happening is the signal reaches the end and part of the signal is reflected back. Usually it is a little BNC connector that is marked 75ohms with a cap.
A "Humbucker" is to eliminate video issues produced by a ground issue in your system. When the power can't find an ground outlet what happens can be a slight ghosting and a slow rolling horizontal bar traveling through your picture. In audio this usually presents itself as an audible hum. In video you can see it. Not sure what it does to the signal technically, but it has been explained to me that it is really just a magnet that the signal passes through. Can't say that makes much sense to me, but they work. I guess I could Google it if I really wanted to understand how they work.

Brian Mirrlees
08-20-2013, 07:39 AM
Composite video has a 75 ohm impedance. Most video DAs have a bridging input, where the the input signal is bridged to a thru output. The input video to the DA is tapped off of this bridge between the input and the thru output. The purpose of the bridging input/output is to allow direct connection of the input video signal to another video device without having to use one of the outputs of the DA (and corresponding level changes which have been made at that DA point).

If you don't need the bridge output on the DA, then the video signal has to be loaded or terminated in 75 ohms with a "terminator" which is a BNC cap or bullet on one end with a 75 ohm resistor inside wired from conductor to shield. This BNC terminator would be applied to the bridge output on the DA input, and will provide the 75 ohm load to the input video signal.

A video hum bucker is an isolation transformer for video which is designed to remove 60 Hhz interference in the video signal. Sixty cycle interference is typically induced to the video path when various video devices in an installation are powered from different power sources or circuits with differing ground potentials. Or, 60 Hz interference can also occur when the video cable is running parallel to power cable(s).

If the 60 Hz hum is very severe, you will actually see it on the video monitor display as a series of horizontal lines moving thru the video from bottom to top on the screen. You can also detect 60 Hz interference in video by looking at the sync portion of the video signal on a waveform monitor set to the H or 2H sweep.

Determine which video source has the presence of sixty cycle hum, and then place the hum bucking coil in-line on that source. The video source will go to the input of the coil, and the output will go to your switcher.

08-20-2013, 07:51 AM
Sixty cycle interference is typically induced to the video path when various video devices in an installation are powered from different power sources or circuits with differing ground potentials. Or, 60 Hz interference can also occur when the video cable is running parallel to power cable(s).

Both of these can be common when running video long distances.

08-20-2013, 02:37 PM
Here's another couple of solutions offered to me: Get 2 Kramer 1:2 Composite Video Amplifiers (http://www.kramerus.com/products/model.asp?pid=78&sf=20#1). Split the output from the camera using one of the amplifiers. Run coax 200 feet to another amplifier. Run another 200' coax to the Tricaster.

OR, buying a Composite Video Distribution Amplifier with loop through (http://www.extron.com/product/product.aspx?id=mda4veq&allparts=1&s=5), connect the nearest monitor to the loop through and run the 400' coax/cat5 through a Twisted Pair Video Transmitter (http://www.extron.com/product/product.aspx?id=mtptav2&search=MTPTAV).


08-25-2013, 10:42 PM
Here's the final configuration that works well: Kramer PT-102VN 1:2 Composite Video Distribution Amplifier and both the Kramer Electronics 711N Composite Video and Stereo Audio Over Twisted Pair Transmitter and the Kramer Electronics 712N Composite Video and Stereo Audio Over Twisted Pair Receiver. I can go 1000'!!

11-07-2013, 02:25 PM
Where are the two long runs going? How close together are the two devices being fed? If they're close together, run a single cable as far as you can before connecting to a VDA. Then you'll have way shorter runs to deal with after the split for the connected devices.