Detecting where a coax cable goes to

I have what I think is an unsual question which I couldn't find an answer to: in my attic there is a coax splitter with several coax outputs to coax cables which snake into the ceiling and disappear in the boweles of the house. They are all of the same color and have no identifying marks. In the house itself, there are coax jacks in several rooms.

And now the question: is there a way to determine, without buying expensive equipment, which cable in the attic leads to which room? Since not all coax jacks in the rooms are connected to a tv, it's not just a matter of disconnecting one cable after another from the splitter and seeing which tv loses its signal.

Reply to
bruno.lerer
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"Since not all coax jacks in the rooms are connected to a tv, it's not just a matter of disconnecting one cable after another from the splitter and seeing which tv loses its signal" I can think of two ways right away. The way I would do it is to get a small TV and conenct it to a cable outlet. Turn the sound up high. Go in the attic and perhaps with a helper listening disconnect one coax at a time. bingo.

the hard way would be to use a volt-ohm meter. disconnect all the coax in the attic and jumper one outlet across itself. then check in the attic for the line with 0 resistance. ...thehick

Reply to
thehick

Cut a small cable in two.. On one cut end wire up a 9v battery connector. On the other cut end wire up a buzzer, or at least strip it so you can use a meter to test the wire and shield.

Hook the 9v at the wall outlet. Go up to the splitter and check each lead that comes up to the splitter. When you buzz, or get a 9v reading, you've found that room.

Reply to
Noozer

Hi, I saw cable guy using a 9V battery with coax connector and buzzer to trace coax. Simple but works. Tony

Reply to
Tony Hwang

also: cable tv company here will upgrade your splitters and replace the cable ends from the pole to your jacks to deliver a nice picture to your cable tv's. and: maybe time to break down and buy a digital multimeter for $25. look what you can fix with it at:

formatting link

Reply to
buffalobill

... as long as there's not another splitter between the battery and the buzzer.

Reply to
CJT

Sorry for the newbie question, but what happens if there is a splitter?

Also, is possible to tell - and if so, how - if there are one or more splitters between the attic and the room?

And, another also, will the presense of one or more splitters affect the other approach suggested by others on this thread (volt-ohm/multi meter)?

At least thehick's other idea - using a portable tv - should still work...

Reply to
bruno.lerer

If there's another splitter, then it depends on the particular splitter in question -- some will pass DC, others won't. If it doesn't pass DC, then neither the buzzer nor the meter will register the battery's voltage.

As for using a TV, it'll introduce some ambiguity there, too, since you might have two (or more) equally good signals.

If you have the same number of wires in the attic as wall connections, there's probably not another splitter.

Reply to
CJT

If there were more splitters, it would be unlikely that they would be hidden away somewhere. Splitters and connectors do occasionally fail and they would have to be accessible for service. Depends on the intelligence of the installer.

Bob

Reply to
RobertM

If the cable was daisy chained as was the custom years ago, there could be a splitter at every outlet. My last house had a run with 9 splitters in it. Needless to say, it didn't do very well with a broadband connection!

From:RobertM snipped-for-privacy@newsgroup.com

Reply to
BruceR

Let's assume there are no other splitters involved. Forget the battery method. Go to RadioShack or equivalent and buy a 75 ohm terminator. If you don't own a test meter, get the cheapest one you can find that measures resistance. Disconnect all the sets that are attached to the cable system Put the terminator on one wall outlet. At the splitter disconnect, all the cables. Take the meter and at the splitter end find the cable that measures about 75 ohms between the center pin of the cable connector and the outside of the cable connector. Tag both ends of that cable. Move the terminator to the next wall outlet and repeat. Having an assistant who can move the terminator around and communicate to the attic is a great time and effort saver.

Charlie

Reply to
Charlie Bress

Unless there is a complet floor in the attic, I would follow the wires into the ceiling, lifting the insulation a bit until I find where they go down into a wall, from the top. In the attic, a wall looks like the broad side of a 2x4. The wire is not likely to stray too much once it heads into the wall. The ones you can't trace this way, you can trace with the other methods given.

Remove NOPSAM to email me. Please let me know if you have posted also.

Reply to
mm

You can even just use an alligator switch to short the center conductor to the side and check for 0 ohms.

From:Charlie Bress snipped-for-privacy@paamail.com

Reply to
BruceR

Yes, there is. Disconnect all of the cables from the splitter. One at a time, test the cables for continuity using a cheap ($15 or so at RatShak) VOM meter while your SO walks around downstairs shorting each jack with a piece of wire. When the meter beeps, shout "STOP" and have her shout back what room she's in. Write it down on a piece of adhesive tape and wrap that around the cable. Repeat.

Reply to
Robert L Bass

Other posters have given you reasonable suggestions for identifying the cables. But I'm wondering why it matters as long as each outlet is feeding the same signal from the same source -- the splitter.

A caveat --

In a setup such as yours, each unused outlet should have a 75 ohm terminator. Radio Shack has them. Unterminated cables can mess up the signal to the active devices on the network.

SJF

Reply to
SJF

That goes for any unused connections on the spliter(s) as well.

Reply to
Kevin Ricks

How about a slight change that reduces the work a lot.

Have the person walk into a room and tell you which one it is. Then check continuity on all the ends at the splitter. You only move inches between test instead of the distance between rooms.

When testing, include the ones previously done. They should not show continuity again. If they do, there is a connection between them.

Reply to
B Fuhrmann

"Other posters have given you reasonable suggestions for identifying the cables. But I'm wondering why it matters as long as each outlet is feeding the same signal from the same source -- the splitter. "

Interesting you should ask (and, btw, you seem to be the first to do so...). Anyway, a little off topic, but the reason for the question is this: the cable company's feed starts from the attic and is being split into various rooms as I described. What I would like to do is intall in the attic an HTDV over-the-air antenna and feed the signal from that to an HDTV in one of the rooms.

I don't want to run a new cable from the attic thru the second floor to the first floor (where the HDTV is located); I just don't have the skills (and probably tools) required for that kind of job. So, in my infinite wisdom, I figured that if I can determine which cable goes to the room in question, I'll just disconnect it from the splitter and connect it to the OTA HDTV antenna in the attic (using a coax coupler) and to the HDTV in the room and voila! OTA HDTV reception.

I understand that by doing that I give up regular cable reception in that room but (1) it's a problem for another day and (2) it's not really much of a problem anyway since I don't intend to user that for the usual cable fare.

So that's the reason....

Reply to
bruno.lerer

Well, that's a departure from the other proposals :) Just to be on the safe side, I'm going to get tomorrow both a buzzer and a 75 ohm terminator!

I already have a 9v battery and even a multimeter - analog, unfortunately, but it does measure resistance, so I should be all set (assuming by wife agrees to act as the assistant...)

As an aside, I must say it NEVER occured to me how useful a multimeter is. Talk about learning something new every day.

Reply to
bruno.lerer

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