> the whole house one looks like what want. that's really the function
> I'm trying to fulfill. I can get a smaller u.p.s. for the computer, and
> that just to shut down gracefully upon power loss. kind of a stupid
> question, but reading that, it says 120v
Not sure what you're looking at ... I see 120v/240v meaning it will work for
either one.
> the lines to the t.v.s have the amp, but apparently the amp
> will interfere with the cable modem's function, and a seperate line must
> be split off, pre-amp, to feed the modem.
That's true, sort of. Any amplifiers between the modem and the cable station
have to be "two way" or bi-directional amplifiers. The common, run-of-the-mill
TV amplifier only works one direction. Here's a bi-directional version :
http://www.ramelectronics.net/html/rf-cable-satellite.html#amp
There has to be a filter between the cable modem and the televisions, which is
no doubt in the splitter the cable company provided.
> I've taken to viewing the cable modem as a sort of fuse/surge protector
> itself - at least it isn't frying the computer.
That's reasonable enough, if it's their modem. But I'd still want a surge
protector on the lines between the cable modem & my firewall.
> and you really can't say for sure that it's the cable, since
> the cable is plugged into the amp, which is plugged into the electric
> line, except that only cable stuff was hurt and not electric-only stuff
> (which you'd expect with an electric surge) and the modem is supposed to
> be downstream of the amp (I'm told the amp has a one-way check to keep
> the power boost from feeding back into the line to the modem), yet it's
> been hit.
Seems strange to me, especially since I would expect the amp to be pretty good
at not passing center conductor surges through. I wonder if perhaps the amp or
shield isn't grounded properly. Every amp and every splitter should have a
screw that should be connected to a good solid earth ground ... but my cable guy
said "Oh, that's not necessary, it'll work fine without it." That's true, until
something like a nearby lightning hit induces a big voltage spike into the
shield. Also, lots of people use water pipes for earth grounds, but water pipes
frequently have insulators in them these days. Especially if your house has
been re-piped with copper, there should be an insulator between the copper and
the (steel) water main. Water heaters should also be insulated (so never use a
hot water pipe as a ground).
> I guess the bottom line is I need to be able to protect both the coax
> and electric lines from surges. bad.
Yup, it's a pain alright. Seems like the cable company and electric company
should be legally obligated to not introduce lightning strikes into your home,
but that's not the way it is.
Randall
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