On 11/19/06 6:42 AM, in article
9, "bz"
wrote:

Joerg wrote in news:6207h.6722
:

Its hard to peg characteristics. Would a modem be considered a 200 ohm
nominal load on the phone line?


IIRC, phone lines are a nominal 600 ohm impedence.



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