I haven't been able to find a toner that can isolate a coax cable in the middle of a run without cutting the cable. I have the Fluke toner which is great to find the ends of the cables and a couple different Klein tools toners that you can mark and find at the other end. I'm looking for something that can find a cable in a bundle in an attic for example.

Is there such a device?

An ordinary phone toner and wand will do it. It's the method that's a revelation.

Here's what I do:
Connect one terminal of the tone generator to power ground.
Connect the other terminal to the shield of the cable you're looking for.
Check for signal with the wand. Don't want to accidentally leave this on "continuity"!
Go where you expect to find the cable you're looking for.
Spread out the cables across your hand, flat to the palm, with no overlaps or crossovers, with at least 1/4" between the cables. Since this test involves detection of minute differences of induced noise, you want all the cables to have the same range of capacitive coupling to your hand.
With the other hand, touch the jacket of each cable. The one with the loudest tone (and the lowest hum) will be the cable you're looking for.

A signal is induced from the wanted cable into every adjacent cable, its strength correlating with how far a distance they are parallel, but that induced sound will only be the same volume if they are parallel for a hundred feet or so. I think. I've actually never seen that. I've never seen that method fail.

Any cables that have been connected to ground will improve the ease of finding the cable you're looking for because their induced noise is grounded out. Cables not connected to anything will have a lower toner signal and usually more hum than the cable you're looking for.

Once, with this method (I feel like I should say 'at band camp' here), I could not find the kind of strong signal you'll get used to finding this way. I got very weak signals on several cables, but a slightly stronger signal with hum on one cable. I came up with the thought "this is acting like a cable that is next to the one I want, but is not connected to it. Let's see how far this goes."

I then popped a ceiling access and went into the attic... only to find two pieces of cable tied in a large loose knot. Whoever prewired ran out of cable and tied these together to finish the run, probably thinking to come back later. I connected them and easily found the other end.

The point there is that the cable I located exactly fit the description I'd come up with: I found "a cable that is next to the one I want, but is not connected to it."

The Fluke toner has an indicator of signal strength that is helpful in this sort of situation.

Thanks guys. I've be been connecting the tone leads to the mesh shield and the copper center conductor. You're saying to connect them to the mesh shield and an ac receptacle ground? ? What do I shove in there to make ground?

remove the outlet faceplate and connect the alligator clip to the ground screw on the side on the outlet. or use a small screwdriver in the ground hole

Tom, you've got to let go for a minute of everything you think you know about these tone/wand devices.

There is no hot and there is no ground. Red and black are irrelevant here. There are two outputs that are at different voltages from one another. When connected to stuff, the wand can sense the signal. But how you connect it matters.

If you connect the two leads of the toner to the two leads of any wire, be it quad shield, cheapass RCA, or twisted lead, then you have to be at the other end of THAT CABLE for the wand to pick up the signal. That is, in that mode you can read the signal at up to maybe four inches, sometimes as little as zero inches: you have to touch the bare wire. Connecting to the two leads of a wire almost completely captures the signal on the wire, so you have to be VERY close to pick it up.

But your case wants the cable to RADIATE signal so the wand can detect it anywhere along the length. Turn the cable into a broadcast antenna: electrically ground one of the toner wires to ground -- note that the moment you do that, the wand CANNOT pick up ANY signal on that toner output! Then you connect the other output of the toner to the wire you're testing.

Remember we're trying to radiate signal here, so if you connect the other lead of the toner to the center conductor, the shield will keep the signal from radiating. You have to forget what you think you know about this device and connect the other toner lead to the SHIELD of the wire! It then radiates nicely.

I've tracked speaker wire in the attic that was not in conduit by connecting the toner in this manner and just walking through the house with the wand above my head! I could hear the toner through the wand speaker from four feet away from the wire!

BUT if the wire was in a conduit, or one conductor of the speaker wire was connected to ground, the radiated signal was tiny and I could not pick up the signal with the wand.

Going back to coax, first, it doesn't matter if it's quad shield, dual shield, RG59 with 40% braid, or whatever.

At this point I'd just be repeating myself. Don't worry if you don't understand how this works. My other post has the most complete and exact description of what to do that I could come up with. Follow it to the letter and see what happens.



Follow what I said to do.

Though I've told you to just follow and see what happens, I'm intrigued by "What do I shove in there to make ground?"

What the hell are you talking about? Shove in where? Want a technical answer? Ask a technical question.

You've correctly gathered that I mean "electrical ground." Are you trying to figure out what you should shove into.... the neutral? Just try what I told you to do.

By the way, I showed this method to a veteran Pacific Bell guy in 1985 and he was blown away. He had NEVER heard in his twenty years of work that you could hook up a toner this way to locate a wire, so don't feel like you're alone in not getting this!

Running one toner lead to electrical ground can be a lifesaver

Every wand I've ever used has a volume control and an LED. You can adjust the volume control so that the loudest signal turns on the LED, and you can do this during test so the LED shows which is strongest when it's hard to tell by ear, for instance if it's noisy in the test environment.

(The first wand I ever saw was on the ground near a telephone pole, with no phone man in sight. I was about twelve when I found it. It used tiny vacuum tubes and had a tiny 90 volt battery for plate voltage and another battery for filament voltage. And it was about the same size and shape as today's wands!)

or...do what i said....
I know what you meant - no lecture

Having a fellow coworker hold one lead at the toner side also does the trick. Grounding it to a receptacle is what is more likely though.

I'm tired and trying to calm down from a long day.

But.

PLEASE DO NOT REMOVE THE COVER PLATE OF AN ELECTRICAL OUTLET OR STICK ANYTHING INSIDE THE ELECTRICAL OUTLET.

Where is the hire a pro sign here?

THIS MAY CAUSE SERIOUS DAMAGE AND/OR POSSIBLY DEATH.

This would be cause for immediate dismissal at a minimum.

Shafer,
I can understand your concerns if your techs are not professional enough to know where the dangers are. If you fire someone for removing a cover plate to access an electrical ground, you have not trained them well enough for you to be secure that they understand what they're doing.

And don't all installers do things every day that civilians think are dangerous?

Let me not write my usual long post: all installers should know how to access an electrical ground safely.