General cable modem questions

[videobruce]

I have had DSL for years and never had any experiance with cable modems. I have a few generic questions about them. The one in use is the Motorola SB5100 on what was Aldelphia, now Time Warner cable. There is also a Linksys router in the mix.

1. Adding a broadband amp (US made Winegard 40-1000MHz) seems to kill the modem. Is it because of excessive signal or is there a need for coverage below 40 MHz? Mind you, this isn't one of those cheap no-name Chineese made wonders. It is only a 10db gain, so I doubt it is a excessive signal issue. I would say there is around +5-10 dbmV of signal with the amp.
2. I was told (by TW support) that you have to leave the configuration of your NICs' to "Obtain a IP address automatically". Is this true? I perfer to assign each conputer with a static IP address. With DSL, I have no issue here, so I don't understand why cable would be different. What does the output of the router have to do with what the modem sees??

Hope all of that makes sense.

[classicsoftware]

There is NO need for a broadband AMP. I think if you get a linksys router, you can turn of DHCP and assign IP address yourself.

[KenJackson]

I wasn't even aware that broadband amplifiers exist. Did you install it before the splitter or after? Did you buy it to improve your TV picture? Does it help?

I also have a Motorola SB5100 and a Linksys router (but I have Comcast service). I have the router configured to do NAT, but not DHCP, so like you I assign my own static local IP addresses and am pleased with this setup.

Classicsoftware is probably right about the amp. When my modem was dropping out, I called Comcast and they sent over a technician that replaced the splitters to raise the signal strength a little, which solved the problem.

[videobruce]

I wasn't even aware that broadband amplifiers exist. Did you install it before the splitter or after? Did you buy it to improve your TV picture? Does it help? Most/many amps are broadband now. Some still are VHF/UHF for antenna only. I never even consider those dime-a-dozen Chinese POS wonders. It's a complicated situation where everything is and can't go into it here.
I orginally was going to amp after the modem, but changed the location of the amp. The signal comming into the house was actually good and they aren't far from the HE, but with all the TV's 'online' (pardon the expression) it's kinda a mess.
It's not a problem to split the feed (after a inital split) and send one side to the modem and the other to the amp. That signal is good.

I figured a too low signal would be a problem, but whenh I set it up initally all was fine. It was because of what I though was a very slow connection speed, I startrd to troubleshoot a non problem. As I don't have cable internet I didn't know they offered three levels of service. the slowest is 380kbps (beleive it or not) and I was expecting between 3 and 6 Mbps. The uplike is faster that the download. :rolleyes:

I have the router configured to do NAT, but not DHCP On the home page of the router access there is a choice of automatic DHCP and a few others (including PPPoE for DSL). The router is set for auto DHCP for cable. This isn't what you are talking about is it?

[KenJackson]

On the home page of the router access there is a choice of automatic DHCP and a few others (including PPPoE for DSL). The router is set for auto DHCP for cable. This isn't what you are talking about is it? I can't get to the router's web page right now because I'm not at home. I don't remember if it offers any PPPoE options, but I ignored it if it does.

But now that you mention it--it offers DHCP two ways. I do use DHCP on the WAN side to accept a non-static external IP address from my provider. But on the LAN side, I selected the network address and range to use and I also set the local DHCP automatic addresses to a small subset of the segment so they wouldn't get in the way--and I don't use them.

[videobruce]

But on the LAN side, I selected the network address and range to use and I also set the local DHCP automatic addresses to a small subset of the segment so they wouldn't get in the way It's the local DHCP that I can't find. I have the manual and will look through it.

[classicsoftware]

It's on the first page on the router firmware. Under Local DCHP.

[KenJackson]

Oops! Now that I'm home and looking at my router's web page, I see that I do not have a Linksys router--I have a NetGear RP614v3 router.

[pangea33]

This topic was addressed in this thread: http://pcguide.com/vb/showthread.php?t=44149&highlight=cable

The executive summary basically is that a cable amp can ruin your broadband signal oftentimes. If you split the cable from the wall sending one to the cable modem, and the other output to the amplifier, then all standard cable devices are downstream from the amp, you may have success.

[classicsoftware]

Only a fool would attempt to bump the amperage on your cable system. If you don't have enough power, you call the cable company and have them the check the wiring. What are you paying a monthly fee for anyway? It's their responsibility. Also, if you up the power too much and let's say damage the modem, the guess whose responsibility it is? It's not your wiring, it's the cable companie's and most of the time it's their modem too and now a days it may even be their router. If they want to up the power let them, don't do it yourself. The risk of harm is so much greater than any gain I can't see where it would ever be wise to do this on your own.

[videobruce]

If you split the cable from the wall sending one to the cable modem, and the other output to the amplifier, then all standard cable devices are downstream from the amp, you may have success. It's already done and was the orginal plan. Because of the layout the plan was changed.
Only a fool would attempt to bump the amperage on your cable system. Fool? Amperage?? Try signal. When the signal level is low (because of the number of taps involved), it would be a fool that would watch noisey pictures when a decent amp would make up for the loss. If you don't have enough power, you call the cable company and have them the check the wiring. It's called signal and they are only required to supply 0dbmV at the set, as in one set. Anything else is optional. t's not your wiring, it's the cable companie's Not necessarly. Up to a certain point it is theres and the rest can be yours. f they want to up the power let them, don't do it yourself. Is this a cable TV modem thread or a electrical power company discussion. The risk of harm is so much greater than any gain Exactly what "harn" are you talking about?? :confused:

[classicsoftware]

This is America and you are free to do what you please. I have been a cable Internet subscriber from the very beginning. You need to let the cable company control the signal strength. I would not up the signal strength which I believe is measured in amps. So increasing the strength ups the amperage. You can damage the cable modem which will cost you money to replace and worse if it's their modem they can charge you for that and the labor to do it.

If you do not have enough signal strength it's up to your cable company to fix it. This is NOT a DIY project.

[videobruce]

I would not up the signal strength which I believe is measured in amps. RF signals are measured in dbmV. Amps is a measure of electreical current normally use on the AC or DC input side of a device that actually powers up the device. It could also be used on the xmit side of the signal as in from a TV transmitter regarding power on the feedline to the antenna. But, since that isn't what we are talking about the term "amps" has no bearing here. While you could overload anyreceiver, it is unlikely in this case, BUT, since 99% of the amplifiers out there aren't compatable with these modems anyway (aparently), placing an amp on the line going to the modem is notan issue. It's 'boosting' the low signal to the rest of your household where the issue is. If you do not have enough signal strength it's up to your cable company to fix it. Only up to a point as I said before. [B]They are only required to provide 0 dbmV at the set. 0dbmV is an archaic figure from the 50s' since that was what was determined to be a acceptable picture (on a 14" B&W set) at the time and AFAIK, it hasn't changed. Hardly fits todays TV's (digital aside). This is NOT a DIY project. Yes it is. It's done every day. Just look at all the home TV amplifiers available, most are speced for cable (or so they say).