New Contributor II
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3 Messages
Cable modem surge suppressor
I bought an Isobar Home Theater Surge suppressor (Model ISOBAR6DBS) to protect my Cox internet and phone modem. However, when I interpose it between the Cox coax cable and my modem, I cannot get either an internet connection or dial tone. Can anyone offer any suggestions in this matter? Is this just a faulty suppressor that I should exchange or is it inadequate by design? If it is inadequate, can anyone recommend a suppressor that will work? Thank you.
Accepted Solution
Leo9
New Contributor II
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3 Messages
12 years ago
I just verified with TrippLite that you are all correct. It is designed for analog video modems only ...which makes it obsolete unless you're just connecting to a rooftop antenna. The box does read "protect components on two DSS satellite, cable or antenna lines simultaneously" and lists no restrictions.
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Trikein
Contributor III
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806 Messages
12 years ago
Are either modem getting power? If so, what lights appear on the modem? If I had to guess, i would say the coax protection is filtering the lower frequencies that the modems use for upstream signal. Or it could be the included coaxial cord. Looks like RG5. Try a normal quad shield RG6 with compression connector.
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KipK
Valued Contributor II
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606 Messages
12 years ago
All coaxial surge protectors I know of are inadequate for data service by design. Unless it can pass 5-1000 MHz bidirectionally with <1dB loss and doesn't introduce any noise of its own, it is a bad thing to add to the system.
If the cable was installed properly it will be grounded at the point of demarcation, and there's no appreciable voltage coming over the cable during normal operation so that should be sufficient.
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Leo9
New Contributor II
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3 Messages
12 years ago
Kip, Thanks! There may be no appreciable voltage coming over the cable during normal operation, but what about an abnormal situation such as a lightning strike on a nearby pole? It seems that a similar argument could be made about power lines, that there should be no voltages that could harm connected equipment during normal operation. And the power line going into my service box is also grounded. Am I missing something in what I'm saying?
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Trikein
Contributor III
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806 Messages
12 years ago
Its not that you can't use a surge protector for your cable modem, its just that yours doesn't work. Looks to be for analog only as per specs. What Kip was saying is a surge isn't very likely to damage a modem via the Coaxial if your cable in your house is grounded because the electricity will just find the path of least resistance. The ground acts like a surge magnet, pulling the electricity away before it can do damage. In theory anyway.
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