Newsgroups: comp.dcom.cabling
Subject: Re: RG-59 & Amplifier?
References:  
"Crypt"  writes:

> Also the Electroline amp I'm thinking of getting is model EDA-2100. 

Web page http://www.cabletvamps.com/Products/EDA-2100.htm says:
"The EDA-2100  is a 1-port amplifier. One port amplifiers are the
easiest to install, and are best suited for connecting to your
incoming cable line before you start splitting off the line to go to
multiple TVs. The EDA-2100 is generally the best for use in existing
installations, since it is easy to use, with a single cable connection
in and out."

This kind of ampliifer sound somethign that is OK for splitting 
the incomign antenna signal to different TVs. 
What in you case complicates thigns is that you say you have cable 
modem. A cable modem will not work through a normal antenna 
booting amplifier. The reason is that normal antenna 
signal amplifiers are unidirectional, pass signal only to 
one direction and amplify signal on the way. 
The cable modem uses two way communications over cable TV cable 
(at least all modern systems). If you put an unidirctional 
amplifier on the way, the downstream signal gets through 
amplified, but the signals the cable modem sends out never 
get to the cable company end becasue the amplifier blocks them. 
The cable TV systems that support cable TV use bidirectional 
amplifiers designed for two way commications in mind. 
Those amplifiers will amplify normal TV frequencies normally 
as any norma maplifier, but in addition to it they will 
pass the return signals (frequencies from 5 MHz to 30..60 MHz 
depending on system) on the opposite direction. 
This is accomplished with a special filter inside amplifier unit 
and possibly another amplifier to amplify the return channel 
signal. This kind of bidirectional amplifiers are available, 
but their market is generally more to cable TV companies 
than to consumers.

-- 
Tomi Engdahl (http://www.iki.fi/then/)
Take a look at my electronics web links and documents at 
http://www.epanorama.net/