Need help with cable interference

[WakeBdr]

Forgive me if this is not the correct place to post this, but I have not found any answers anywhere else and Satelliteguys has been very helpful to me in the past. I'm hoping someone can offer a suggestion for my problem.

I recently installed an underground pet fence in my yard. The problem is the cable tv wire that runs from the cable box at the street to my house. The signal from the fence "jumps" onto the tv cable which then acts like the fence cable. If I let my dog out into the yard to run, she would get shocked anytime she comes near the cable which runs across my yard.

The pet fence manufacturer suggests running the tv cable perpendicularly across the fence line and then no less than 3-5 feet from the fence line in a parallel manner. I have done this. I cross the fence line perpendicularly and then run at least 15 fee away before I turn to run parallel. I do not understand why it is behaving this way since I followed their instructions for this particular scenario.

Does anyone know a way I could solve this problem? Is there a way to insulate the tv cable such that the signal from the fence could not get onto the tv line?

Thanks for any suggestions

 

[cablewithaview]

If possible, I recommend dual shield underground and if it is where you can put it in conduit, that too. With electric fence though, the fence maybe feeding back in your electrical ground. I would recommend putting in a separate ground rod for the fence altogether. by separating the ground from power, it cuts down on interference with your stuff and other people around you. I have had a well feed back on the power 1/2 mile away because of a bad ground. your ground will be key. also keep some distance from the ped or pole.

 

[BrettTRay]

Cablewithaview is right. I would ground the conduit to if you use metal conduit.

 

[cablewithaview]

NO metal conduit ! that will cause more trouble. Just ground the fence separate from power. If you have some 3/4 conduit, put it in. I would try ground 1st and then go from there.

 

[WakeBdr]

There is no ground on the fence. It is not an electric fence like you see for livestock. Here is a link to the fence system: http://www.radiofence.com/dog_fence_premium_1_dog.htm

It is just a complete loop from the transmitter, around the yard, and back to the transmitter.

 

[cablewithaview]

what is the frequencies on that ?

 

[cablewithaview]

If there is nothing wrong with the wire, check your connections. Sometimes a connector may not have a good ground on the coax causing outside interfere to get in. One way you can check for ingress, have you ever had a checker like pattern intermittently or solid on any channel from say 17 to 21 ? If so, then it's a matter of eliminating the source of your ingress. A RF modulator, VCR, splitter, bad connector, etc. Your cable provider should be able to trouble shot that with a spectrum analyzer or do it the old fashion way, if you feel it is on the outside. I have had a TV to have that problem and the only way you can tell is to take a converter box and set the TV on 3 or 4 and if the problem is not in the box then it's the TV having the ingress issue, if it is in the box also then you have to back up from that point.

 

[WakeBdr]

I'm not sure what frequencies it uses. I tried searching online for it, but can't find it. I'll check the transmitter to see if it has anything written on it.

cablewithaview: I actually only get cable modem from my cable provider.

The problem is the tv cable picks up the signal from the fence wire and acts like the fence wire. It will cause the dog collar to shock if it gets close to it. I need a way to prevent the signal from the fence from getting onto the tv cable.

 

[cablewithaview]

return on the internet is in between 17 & 32 mhz and forward depends on the provider. ask your provider what channel they transmit on for the forward. You may have something feeding back and going back out on the cable. Disconnect it from the tap, if it still causes trouble disconnect the modem, still does it disconnect the ground leaving nothing hooked up to it on either end. try one thing at a time and then reverse. The cable, being underground, you may have a small hole or splice in it somewhere causing it to induce on the cable. If so with everything else disconnected then the cable is bad. It takes a little time to trace it out.

 

[WakeBdr]

I tried one of those things yesterday when I was working on it. I disconnected the cable from the tap, and it worked like it should. The tv cable line did not cause any interference when it was unhooked. I also cut the power to the fence to see if the tv cable alone would make the collar go off. It did not make the collar go off when the fence was powered off. So, it appears the signal is "jumping" to the tv cable somehow.

I found some documentation on the web that says the fence operates in the 10 kHz range.

 

[cablewithaview]

did you hook it back then disconnect from the house? this should narrow it down a little better for you for sure. If it is in the underground cable, it sounds like it is exposed somewhere underground. Is there a ground rod in the ped? sometimes they will put in a rod inside the ped an attach it to the back of the tap or amp housing.

 

[WakeBdr]

I did not unhook it from the house. I will try to do that when I next get a chance. What will this tell me?

I'm not 100% familiar with the correct terminolgy, so I'm assuming the ped is what I've been calling the tap at the street. There is some sort of grounding device inside that, but I don't remember how it is connected. The line is also attached to my house's grouding rod right before it goes into my house.

 

[WakeBdr]

I unhooked it from the house tonight, and it still set the collar off. What does that mean?

 

[cablewithaview]

If you disconnect the wire from the input side breaking the ground of the coax to the ground of the house and it still does it, I would about say it would have to be the ground in the ped (tap) that it's feeding back on or the wire underground has a splice or hole in it. If disconnected on both ends and don't do it, then they cable should be ok. I'm thinking it's feeding back on the ground on one or both ends(house and/or tap).

 

[WakeBdr]

What can I do about that? If I disconnect it from the tap (input side), it doesn't do it. If I disconnect it from the house, it still does it.

 

[cablewithaview]

call your local cable company and have a service or maintenance tech come out to the house. it sounds like it maybe feeding through there ground in the ped. they can elimnate it by doing some stuff. explain what you have done and what you found out. They may have a report down the line of trouble and haven't been able to find because of you. who knows?, but give them a heads up and go from there. It may be resolved by them unhooking there ground from the tap housing itself.

 

[cablewithaview]

If you disconnected from the ped and does not do it, then everything on your end sounds like it checks out. if it is disconnect from the house with it disconnected from the input side of the ground block, then I would question the ground in the ped OR possibly a hole in the cable underground.

 

[WakeBdr]

I'll give them a call tomorrow. I'm sure I'll have a pretty difficult time trying to explain why they need to send a tech out, though.

Thanks

 

[cablewithaview]

once you explain that your interferring with there cable, I don't think you will have a problem getting someone out there.

 

[cablewithaview]

I wish I could be of more help.