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TV Interference from cable modem.

I know this has been hashed and re-hashed and I've read too much, now I'm confused.

My setup is in a camper which has a living room, front bedroom and back bedroom. Believe it or not, there are three tv's in the camper. Cable recpetion is excellent on all TVs with the cable modem unplugged. I have a splitter, brand new, but a cheapy with no specs on it, that splits off of one of the tv connectors to the cable modem. The rest of the wiring is inaccesable other than a cable jack in each room.

Cable modem works great for internet access when plugged in to cable but my tv recption gets wrecked. I get noise on channels 2-7 and channels 52-60 are virtually wiped out by snow and are unwatchable.

I'm thinking that I should split the wire where the cable comes into the camper running one wire to the cable in jack that feeds the the tvs with a 50mhz highpass filter and then another cable going to the cable modem all by itself. Does this sound like a reasonable approach or are there other things to consider ?

Any help would be appreciated.

Thanks,

Mark

Reply to
Mark
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They are cheapy TVs, 13" for $59 at best buy.

Reply to
Mark

If the modem is putting out interference on the TV channels, then the high pass filter will not stop it. Further, if it's doing that, it's operating out of spec. If it's owned by the cable company, get them to fix it. If it's yours, you have to take it back to where you got it from. Further, the interfering signal might be going over the shield of the coax, in which case, a ferrite choke may fix the problem. If the TVs are simply sensitive to the transmitted signal from the modem, the high pass filter might help, though this situation indicates a sub standard TV.

Reply to
James Knott

I would start with a ground block for the incoming cable and Quad-Shielded RG6 cable thoughout.

Then a good 4-1 splitter (digital 4-way splitter (5-1000Mhz) with the first tap going to the cable modem and the other three off to the TVs (or a 1-2 with cable modem on first and then split the second again for the TVs - that would give you less of a dB drop on the cable modem side, but more on the TV side). If you still have problems once you are hooked up right, then you could look at filters and such.

Reply to
$Bill

Thanks all for the advice. I'm going there this weekend and will try out some of the suggestions and post back the results.

Mark

Reply to
Mark

I'd start off with replacing the splitter with a high quality one that has blocking capacitors on all ports. The importance of good splitters can be read here: (the first 2 articles). Blocking capacitors are gone into in a detailed explanation in the "Hum Got You Down" article.

A cable modem should always be on its own dedicated splitter and be the first device in the line. Among other things, doing so increases the isolation between the cable modem and the TV sets, which is always a good thing.

CIAO!

Ed N.

Reply to
Ed Nielsen

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