On Tue, 4 Nov 2003, Stephen R. Besch wrote:
> 5) Attempt to balance the hybrid at the 2-line to 4 line interface.
> Why: 99% of the time, this is where the echo originates and
> this is where is should be fixed. Unfortunately, this is not for the
> faint of heart, but if your line card has a hybrid balance adjustment
> (many don't), use it. Also, with multiple simultaneous calls, this may
> be the only real solution. Part of the problem arises from the use of
> lower impedance telephone wiring nowdays. The typical characteristic
> impedance of Cat5 twisted pair is about 100 ohms and many line cards are
> optimized for a 600 ohm line. This is made worse if the DC resistance of
> the wiring to the CO switch is relatively low. I haven't tried this
> myself, but you might try something as simple as a 500 ohm variable
> resistor in series with the ring line and adjust for minimum echo. If
> it gets worse, you haven't lost anything, just take the resistor out of
> the line. If it works, measure the value of the resistor when set for
> minimum echo and replace it with a fixed value resistor.
I've had to do similar things to lower loop current. Be sure you get at
least 1 watt resistors and put the same size on the tip and ring. Putting
resistance on only one wire will throw other things off.
dave
--
Dave Weis "I believe there are more instances of the abridgment
[EMAIL PROTECTED] of the freedom of the people by gradual and silent
encroachments of those in power than by violent
and sudden usurpations."- James Madison
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