Cable Modem Hookup

[Jerry Bruette]

New cable modem should be here in a couple days. Can I use any type/brand of coaxial cable to hook it up or should it have some magical rating for internet/modem/computer use?:confused:

[Mike Henderson]

I think the old standard was RG-59. I've heard that RG-6 is better. But I did not work in the cable modem area (I worked in dial up modem area).

I think it's a 75 Ohm cable.

Mike

[David Masters]

Both RG-59 and RG-6 are 75 Ohm cable. The RG-6 generally has better shielding and can used for longer runs. If the run is more than a couple of feet, I would probably use RG-6, but I have plenty of that cable around here. I'm fairly certain that under 10-15 feet, you'd be okay with RG-59.

[Ole Anderson]

The standard for cable installers now is RG-6, even for short 3 foot cables.

[Larry Frank]

I did a bunch of new runs in my house and used RG 6Q which is the quad shielded version. Is the extra really needed...maybe ?? I figure that because some of the runs are closer to electric wires I would use it.

[Jason Roehl]

Our cable company will give you cable if you ask for it. I found that out AFTER I had purchased the friction-fitting tool and some terminations for quad-shielded coax cable.

RG-59 is obsolete. Don't use it with anything digital. Also, don't use any coax cable that has terminations crimped onto the ends.

Your new cable modem will probably come with a 3' or 6' cable anyway.

[Dan Hintz]

The easy answer? Use the provided 3' of RG-6 and be done with it.



The more complicated answer? Take a look at this breakdown of losses at various frequencies:

RG 59 Signal Loss (in dB) per 100 ft:

Loss at 50 MHz: 2.4 dB
Loss at 100 MHz: 3.4 dB
Loss at 400 MHz: 7.0 dB
Loss at 900 MHz: 11.1 dB
Loss at 1000 MHz: 12.0 dB

RG 6 Signal Loss (in dB) per 100 ft:

Loss at 50 MHz: 1.5 dB
Loss at 100 MHz: 2.0 dB
Loss at 400 MHz: 4.3 dB
Loss at 900 MHz: 6.8 dB
Loss at 1000 MHz: 7.0 dB



Cable modems receive data from the head-end in the 50-1000MHz range, and transmit back in the 5-50MHz range (shared with everyone else in the neighborhood). what the chart above doesn't show is RG-6 is not well-suited to shield noise at frequencies much below 50MHz.

So, RG-6 is best for reception, but RG-59 is best for transmission. You can't have the best of both worlds, but since you receive the majority of data traffic rather than transmit, the RG-6 is the best choice.

[Jerry Bruette]

I did a bunch of new runs in my house and used RG 6Q which is the quad shielded version. Is the extra really needed...maybe ?? I figure that because some of the runs are closer to electric wires I would use it.

This is what I was wondering about.

I'm sure I'll use the short whip provided by the cable company, but this is a new service, switching from DSL to cable, so I'll need to run a bunch of cable to a room that doesn't have have a hookup.

Does it hurt the reception if the coax has several feet coiled up and left hanging?

[Mike Henderson]

This is what I was wondering about.

I'm sure I'll use the short whip provided by the cable company, but this is a new service, switching from DSL to cable, so I'll need to run a bunch of cable to a room that doesn't have have a hookup.

Does it hurt the reception if the coax has several feet coiled up and left hanging?
If by "several feet" you mean 5 or 6 feet, then, no, you probably won't notice any difference. You'd have to be really "on the edge" for 5 or 6 feet to make any difference.

Mike

[Duane Meadows]

Are you running to another room for TV, or for internet? If internet, I'd just use a WIFI router, or run cat6 to the second room. If for TV, you need a proper splitter and you will lose about 10db to each tap. If you are going to hook up a second modem, the same applies(splitter and losses), but not sure why you would want to do it that way!

[Dan Hintz]

If for TV, you need a proper splitter and you will lose about 10db to each tap.

Woh woh woh... 10dB is HUGE! You will lose 3dB (theoretically... in actuality, it's probably closer to around 3.1-3.2dB). 3dB is 50% of the signal, which makes sense when you figure you're splitting the signal down two equal paths.

[Jason Roehl]

You should also keep in mind that you should only have one splitter at your residence for digital cable--don't split a cable that's already been split at the service entrance.

[Dan Hintz]

You should also keep in mind that you should only have one splitter at your residence for digital cable--don't split a cable that's already been split at the service entrance.

You have to split multiple times to distribute at some point. Our house has a 1:9 distribution block, which is pretty typical these days for larger houses. There should be plenty of signal headroom coming into your house for a proper distribution. If not, talk to your carrier and get that fixed.

[Duane Meadows]

Woh woh woh... 10dB is HUGE! You will lose 3dB (theoretically... in actuality, it's probably closer to around 3.1-3.2dB). 3dB is 50% of the signal, which makes sense when you figure you're splitting the signal down two equal paths.

You are not just 'y' connecting 3 wires... and if you do you will have loss due to impedance mismatch and other issues. Check specs, 5.5-7db is usually about minimum loss for a splitter. Line tap, 15-20db more typical. They look the same, but are for different applications. Good reason to know what you are looking at/for, and the effects of inserting one.

Oh, and as to the original question, I'd use RG6 unless you just happen to have RG59 laying around. For 20-40 feet, not that much difference though. It is in addition to th splitter loss though. Don't take long to get to or exceed that 10db point though.

[Duane Meadows]

You have to split multiple times to distribute at some point. Our house has a 1:9 distribution block, which is pretty typical these days for larger houses. There should be plenty of signal headroom coming into your house for a proper distribution. If not, talk to your carrier and get that fixed.

You probably have enough headroom if the cable company knows you are using a 1:9 distribution block. If you add that to service that was set up for one tap, you are very likely to low signal issues! They won't push +40db at you you just in case.

[Dan Hintz]

You are not just 'y' connecting 3 wires... and if you do you will have loss due to impedance mismatch and other issues. Check specs, 5.5-7db is usually about minimum loss for a splitter. Line tap, 15-20db more typical. They look the same, but are for different applications. Good reason to know what you are looking at/for, and the effects of inserting one.

What, exactly, are we talking about, a simple splitter or a distribution network? A splitter is about 3.1-3.2dB, plain and simple. If you're losing 6-7dB in a splitter, throw it away! A distribution network, as I said earlier, is an entirely different animal and not what I thought we were discussing.

And the cable company is not going to squirt just enough power to your house to cover one splitter... if that's what you're measuring, the lineman screwed up.

[Duane Meadows]

Here are spec's on one...

Product DescriptionSize: 2-Way

The Cable Matters Gold Plated Coaxial Splitter splits a single incoming coaxial signal from cable television (CATV), VCR, satellite receiver, cable box, or antenna into multiple outgoing signals. Gold plating ensures a corrosion free connection. Convenient and cost effective 2-pack coaxial splitters can be used on different devices.

Specifications
- Input: 1x Coaxial Female
- Output: 2x Coaxial Female
- Frequency: 2.4 GHz
- Supports DC Pass Through
- Plating: gold plated
- Insertion Loss: 5-1000 MHz: ≤ 5.5 dB; 1000-1750 Mhz: ≤ 6 dB; 1750-2450 Mhz: ≤ 7 dB
- Isolation Loss: 5-1000 MHz: ≥ 17 dB; 1000-1750 Mhz: ≥ 17 dB; 1750-2450 Mhz: ≥ 16 dB
- Return Loss: ≥ 8 dB



I don't design 'em, but I've had to solve many a problem for folks who haven't a clue how to use them properly.

[Jerry Bruette]

You guys are making my head spin.

I think what would be best would be to split the cable as close as I can to the modem and have a longer run to the TV?

What's a line tap look like and how can I tell the difference between it and a splitter?

Should I use the quad shield RG6?

If I split the cable what type/brand of connectors should I use?

[Myk Rian]

Don't worry about it.
I have 2 splitters. The first goes to the modem and the second splitter. The second splitter goes to both TVs.
Nothing special about any of it. I asked the cable installer to leave 2 sections of cable. 20 and 30 feet long. He put connectors on them for me.
Too many people like to show off their technical wizardry, but all it does is complicate things. K.I.S.S. works just fine.

[Dan Hintz]

Here are spec's on one...

Product Description

Size: 2-Way

The Cable Matters Gold Plated Coaxial Splitter splits a single incoming coaxial signal from cable television (CATV), VCR, satellite receiver, cable box, or antenna into multiple outgoing signals. Gold plating ensures a corrosion free connection. Convenient and cost effective 2-pack coaxial splitters can be used on different devices.

Specifications
- Input: 1x Coaxial Female
- Output: 2x Coaxial Female
- Frequency: 2.4 GHz
- Supports DC Pass Through
- Plating: gold plated
- Insertion Loss: 5-1000 MHz: ≤ 5.5 dB; 1000-1750 Mhz: ≤ 6 dB; 1750-2450 Mhz: ≤ 7 dB
- Isolation Loss: 5-1000 MHz: ≥ 17 dB; 1000-1750 Mhz: ≥ 17 dB; 1750-2450 Mhz: ≥ 16 dB
- Return Loss: ≥ 8 dB



I don't design 'em, but I've had to solve many a problem for folks who haven't a clue how to use them properly.



And here's a better one (a 3-way)...
http://www.amazon.com/Extreme-Unbalanced-Digital-Performance-Splitter/dp/B009FMHHX2

3.5dB drop on one leg, 7dB drop on the other two. It's essentially a couple of two-ways in series, hence the doubling of amplitude drop on the second pair. But I would never be happy with a two-way that handed me a 5+ dB drop at each leg.

[Duane Meadows]

And here's a better one (a 3-way)...
http://www.amazon.com/Extreme-Unbalanced-Digital-Performance-Splitter/dp/B009FMHHX2

3.5dB drop on one leg, 7dB drop on the other two. It's essentially a couple of two-ways in series, hence the doubling of amplitude drop on the second pair. But I would never be happy with a two-way that handed me a 5+ dB drop at each leg.

Yeh, it's better on one output, bit worse +- on the other 2. WOW I am impressed! Not! There is also the issue of isolation between taps, but not going there, at least in depth. Oh, and yes I am aware of those and many others.

The point is and remains the 5-7 db thing is quite common. In most installation the difference won't be noticed. But, if your signal is borderline to begin with(and in 40 years as a tv technician many, many are) it may cause issues, especially when going through a couple of them(splitters). It is quite a bit better with a lot of fiber optic lines, than it used to be.

Jerry, line taps are for larger distribution systems such as a retail store. There they run a main trunk line at high level and use line taps to drop the level to individual sets. The line taps look pretty much identical to a normal splitter... really need to read whats written on them to tell the difference.

Quad shield probably over kill unless you are in a high rf location(such as a CB or Ham operator, or radio/TV station or such, next door.

Most any connector properly installed should do the job indoors, outdoors needs to be water proof!

[Jim Becker]

RG6 coax cable is what you want.