Cat5 Video Balun Question

[Chris Chapman]

So the video guys I'm working with just dumped $1200+ to run Cat5 to connect our Gym to the Auditorium so they can do camera shoots in both locations and just use our booth to mix from each location.

They are using Broadcast (NTSC) cameras. Here's the rub. They are using Intelix baluns for the Cat5, and they purchased units that have one video (rated at 75 ohms) and 2 audio (rated 600 ohms). They are trying to send the preview video over the audio feed.

Since the audio ones are rated at a different level, will they be able to send video over the other lines? Right now the preview isn't working and I hve the nutty feeling the spec'ed the wrong balun for.

Thoughts?

[ruinexplorer]

Yes, they purchased the wrong balun. They probably did a test over a shorter run and found that it worked and decided to go this route because it was probably cheaper. Can you still make it work, maybe.

Can you explain more on how they set up the system? Tell us the type of cameras, how they are sending the video to the balun (preview and program), how you are receiving it, transmitting it, etc. Did they buy everything off the shelf or was there a saleman involved? Maybe we can help you make the best out of your situation.

[Chris Chapman]

These are older Broadcast quality cams that are sending 2 lines of video (BNC) out to a switcher. I don't have the specs on the gear, except for the baluns everything is ancient. Like 1980's/ 1990's ancient. I find it weird that they go to the mixer and never use the Genlock.

The video guy thinks he can solve the problem taking a Y off of the single video feed before it goes into the Switcher.

See what happens when you skimp on quoting a system? They purchased all of the other gear off the shelf, they just didn't want to pay the extra $25 per balun for the 6 lines run. Yeah, I know it was only a difference of $300, but they are cheap. And now their cobbled together medusa hair/rats nest of cables and splitters will be even more incomprehensible. (sigh)

And so it goes...

[mnfreelancer]

Seems to me they need some DA's or monitors with looping outputs. Almost every professional video monitor I've ever seen has had looping BNC in/out, in fact most switchers do too. Like you said it's strange they're not worried about genlock return...my guess is Panasonic switcher with digital frame syncs.

[ruinexplorer]

The reason that they might not use Genlock is that either he doesn't know about it, doesn't care about the momentary glitch when switching between signals, doesn't have the ability, or your switcher has internal sync using multiple video cards. Based off of your previous statements, I think that the last one is probably not the case since he is using the wrong baluns based on price. My guess is that he is't aware of Genlock and how to use it if your video engineer is the same person who specified the baluns. Have you asked him why he isn't using Genlock?

Yes, it is probably better for him to send a single signal down the balun and then split the signal prior to it going to your switcher and preview monitor since I assume that your switcher does not have preview capabilities. There is less chance of diversity of signal doing it that way.

[museav]

Originally Posted by Chris Chapman

They are using Broadcast (NTSC) cameras. Here's the rub. They are using Intelix baluns for the Cat5, and they purchased units that have one video (rated at 75 ohms) and 2 audio (rated 600 ohms). They are trying to send the preview video over the audio feed.

Just to clarify, are they trying to send a separate preview signal from the camera or a preview video signal back for the camera? And when you say "preview video" are you referring to Preview on the switcher or individual camera monitors?

If they are trying to get a separate camera monitor signal from the camera, then it would be unusual to use to separate signal from the camera for that, you usually want to be seeing the same signal you are working with. 'Y'ing the signal will not work as it will result in double termination and signal loss. As mnfreelancer noted, many monitors have a 'loop though' input so that the signal can be monitored and then pass on to the switcher. Similarly, many switchers have 'loop through' inputs that can pass the signal on to a monitor. In fact, with some equipment it may be necessary to properly terminate and unused loop though inputs with a 75 Ohm terminator. If you do not have any loop throughs, then a Distribution Amp may be the best option.