Modem Phone line filter

Unplug the house wiring from the CO at the network interface, and see if the line is clean at that point. The problem may be in the Telco side.

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Michael A. Terrell
Central Florida
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Michael A. Terrell
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Joerg wrote in news:6207h.6722 $ snipped-for-privacy@newssvr13.news.prodigy.com:

IIRC, phone lines are a nominal 600 ohm impedence.

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bz

The impedance of a non-loaded phone line is "nominally" 900 Ohms. That's the compromise value used by the Telcos. The actual value could be higher or lower depending on line length. Good modems will adjust themselves to get the best match.

Modern phones should have a off-hook DC resistance of 430 Ohms if they contain a tone dialer, or 330 Ohms if the have a pulse dialer. The 100 Ohms difference is to provide the voltage drop to power the tone generator. Which leaves me wondering what a modem DC resistance would be. Since they are not line-powered, they could be designed to 330 Ohms, but if they were designed to 430 Ohms it would be ok too. By way, this true of U.S. And Canadian Standards.

Don

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Don Bowey

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