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New Visitor
Posts: 1
Registered: ‎10-18-2007

what kind of coaxial cables and splitter do I need to prevent a slow connection?

I know nothing about cables.  I currently have a very fast internet connection.  I recently purchased a TV tuner PCI card.  I found two old coaxial cables in a box, and a splitter of some kind from who knows where.  When I disconnected the coaxial cable from my cable modem and connected it to the splitter, sending one output back to the modem and the other back to the PCI TV tuner, I found that my internet connection slowed to about a tenth of the speed and my digital phone connectivity is now terrible.  Apparently I don't have the right kind of cable or splitter to do what I did.  What kind of cable and splitter should I buy to get this to work?
Recognized Contributor
Posts: 14,085
Registered: ‎10-01-2003

Re: what kind of coaxial cables and splitter do I need to prevent a slow connection?

The cables are probably OK, but you need a high-quality splitter, something with a nice wide bandwidth, like 5MHz - 2GHz (that spec is usually printed right on the splitter).  Even then, introducing any splitter before the modem will reduce the signal strength (the laws of physics are very resistant to breakage!), so if your signal was borderline to start with, you might not be able to get away with this.
Networking Expert
Weil
Posts: 3,567
Registered: ‎07-04-2003

Re: what kind of coaxial cables and splitter do I need to prevent a slow connection?

My local store sells some splitters with very poor labels.  They include a filter to separate vhf and uhf antennas.  Be careful NOT to buy one of these.  They are also one-way.   sam
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runnoft
Posts: 3,193
Registered: ‎09-27-2003

Re: what kind of coaxial cables and splitter do I need to prevent a slow connection?

[ Edited ]
Any new splitter with the kind of bandwidth range EarlyOut is talking about will be bidirectional, but that's another important point.  A really old splitter probably has too narrow a range and may not be bidirectional. 
 
Splitting a signal does weaken it significantly.  Too many splitters in the house can cause your symptoms.  I don't know how it's best to do this with phone service, but with just cable TV and Internet service, what you're supposed to have is one two-way splitter near the entrance to your house ("two-way" means one input, two outputs), and one of those outputs goes to your Internet cable modem and the other output goes to one additional splitter that then splits the signal to all the cable TVs in the house (which would include your PC with the tuner card).  NO OTHER SPLITTERS.  Each time you split, the signal gets weaker, so you have to minimize splits.  Some people have additional splitters in their house, like they'll run one piece of cable up to the second story of their house, and have another splitter there to distribute the cable TV to all the second story TVs.  Then On Demand doesn't work, they see "THIS CHANNEL WILL BE AVAILABLE SHORTLY" on a few digital channels, they have pixellation problems.  People who try to split away the feed to the cable modem to TV sets can end up with both not working.  So since you're having problems, I think you may need to take your feed to the TV tuner card on the PC not from the cable modem area, but from the TV side, which means you need a new arrangement of splitters and cables. 
 
Again, how the Comcast phone service ties into that, I don't know, because that's not something I have any experience with.  You may need to have a three-way splitter near the entrance to your house, and send one feed that goes off to all your TVs (including the PC), one feed that goes to your phone service, and the third one goes to your cable modem.  But a three-way splitter makes the signal weaker to all the branches than a two-way splitter does.  So maybe that's wrong.  Maybe you need to take the phone service from the cable TV split, and only use a two-way splitter.  
 
Another thing to avoid:  don't use a splitter with unused ports.  If you need to split a signal three ways, use a three-way splitter, not a six-way splitter.  Unused ports weaken the signal too much.
 
For a long run of cable, you want RG-6 or RG-6/U, not RG-59 or RG-fifty-anything-else.  Old cable may well not be RG-6.  You should see small white print on the cable telling you what it is.  If you don't see it, I would be suspicious about it, as it might not be up to specifications.  The other thing is that the connectors need to be tight, not just on the devices they're attached to, but on the cable.  Make sure you can't pull the black cable out of the metal connector at the end of it when the connector's attached.
 


Message Edited by runnoft on 10-18-2007 10:03 AM
Regular Problem Solver
Posts: 1,210
Registered: ‎04-07-2005

Re: what kind of coaxial cables and splitter do I need to prevent a slow connection?

[ Edited ]
You might be able to get a freebie if you flag down a comcast truck, they have stacks of them.  The ones they give me are Regal brand, seem to work well, though the ones outside are prone to dying every couple years (but I think any splitter will in those conditions).
 
2 Way splitters have 2 ports that each degrade the signal by -3.5db.  3 ways you can get Balanced which is -5.5 on each port, or unbalanced where they add some resistance to 2 ports (making them -7db) in order to force more signal through the third port (-3.5db).  4 ways are usually balanced with -7db per port.  There are some unbalanced ones out there but it makes the other 3 ports pretty high loss so they aren't terribly common.  You also want to make sure it has a minimum 130db shielding/isolation rating.  1Ghz splitters are fine, technically the 2+ ghz ones can give you a slightly cleaner signal as you approach the 1ghz range, but all mine are 1ghz with no issues.  Someday we'll need more than that once they roll out newer technologies, but for now its not worth paying 2-3 times as much for something that will probably die by the time you actually need it.
 
Ideally you want only -3.5 between the line to the house and the cable modem.  Not because there is a specification saying that, just simply because that is the least possible (well Monster claims theirs is -3.4, whatever).  Unless you don't have TV and you just plug directly in with no splitters, but that's pretty uncommon.  Though in my case I had to have 2 splitters in the line, giving me -7 total, and its ok, but I have a very strong signal to the house (node is like 3 doors down).
 
For the RG-6/U cabling, you want Quad Shield.  There are also different qualities of it.  The standard is copper coated steel center conductor, and steel/aluminum shielding with like 50-75% effective shielding coverage.  The high quality is solid copper center and copper shielding with in the 90% range of effective coverage.  The longer the run you have to make from the outside of the house, the better quality cable you want.  As was stated, connectors are important too.  I use Digicon compression fittings but they require a special tool to install.  Look for a cable that doesn't have cheap "dent" crimps, one with a solid smooth circle base is typically a compression and better quality.  Though the same comcast guy who hands you a splitter will often build you a cable or 2 also using good compression fittings and RG6 Quad.
 
Though most likely its just a junky old splitter.  You can try a good quality new one, and if you still have issues, it could very well be that your signal was borderline and the small amount of attenuation pushed it over the edge, in which case they should come out and fix it (assuming you don't have like 5 splitters in the path which they'll blame on you and charge you for it). 
 
It's amazing how messy the coax in a house can get.  A few years ago I lived in an apartment, and re-did the coax in the whole place.  Put a 2 way on the outside of the house, one fed directly into the office for the cable modem, the other fed a 4-way splitter for the TVs.  A friend of mine moved into the apartment recently after 3 other tenants had been in there.  There were now like 5 splitters hanging in the basement and a rats nest of cabling.  It basically looked like each cable guy that came out just put in a new splitter and cables and attached it to the last splitter that was left the year before.  I cleaned it all up again and their modem signal skyrocketed.  Sometimes you can gain a lot of signal just by cleaning things up or moving cables around.
 
You can get into amplifiers and regenerators too, however to do it properly you're going to be spending a pretty penny for a good one.  Shouldn't be necessary.

 

runnoft wrote:
Any new splitter with the kind of bandwidth range EarlyOut is talking about will be bidirectional, but that's another important point.  A really old splitter probably has too narrow a range and may not be bidirectional. 
 
Splitting a signal does weaken it significantly.  Too many splitters in the house can cause your symptoms.  I don't know how it's best to do this with phone service, but with just cable TV and Internet service, what you're supposed to have is one two-way splitter near the entrance to your house ("two-way" means one input, two outputs), and one of those outputs goes to your Internet cable modem and the other output goes to one additional splitter that then splits the signal to all the cable TVs in the house (which would include your PC with the tuner card).  NO OTHER SPLITTERS.  Each time you split, the signal gets weaker, so you have to minimize splits.  Some people have additional splitters in their house, like they'll run one piece of cable up to the second story of their house, and have another splitter there to distribute the cable TV to all the second story TVs.  Then On Demand doesn't work, they see "THIS CHANNEL WILL BE AVAILABLE SHORTLY" on a few digital channels, they have pixellation problems.  People who try to split away the feed to the cable modem to TV sets can end up with both not working.  So since you're having problems, I think you may need to take your feed to the TV tuner card on the PC not from the cable modem area, but from the TV side, which means you need a new arrangement of splitters and cables. 
 
Again, how the Comcast phone service ties into that, I don't know, because that's not something I have any experience with.  You may need to have a three-way splitter near the entrance to your house, and send one feed that goes off to all your TVs (including the PC), one feed that goes to your phone service, and the third one goes to your cable modem.  But a three-way splitter makes the signal weaker to all the branches than a two-way splitter does.  So maybe that's wrong.  Maybe you need to take the phone service from the cable TV split, and only use a two-way splitter.  
 
Another thing to avoid:  don't use a splitter with unused ports.  If you need to split a signal three ways, use a three-way splitter, not a six-way splitter.  Unused ports weaken the signal too much.
 
For a long run of cable, you want RG-6 or RG-6/U, not RG-59 or RG-fifty-anything-else.  Old cable may well not be RG-6.  You should see small white print on the cable telling you what it is.  If you don't see it, I would be suspicious about it, as it might not be up to specifications.  The other thing is that the connectors need to be tight, not just on the devices they're attached to, but on the cable.  Make sure you can't pull the black cable out of the metal connector at the end of it when the connector's attached.
 


Message Edited by runnoft on 10-18-2007 10:03 AM




Message Edited by Drinkingbird on 10-20-2007 12:57 AM
Bronze Star Contributor
Posts: 129
Registered: ‎09-27-2006

Re: what kind of coaxial cables and splitter do I need to prevent a slow connection?

Also, make sure the center cable sticks out of the F- connector about 1/8 inch because it is carrying most of signals through the cable...
 
higgie
 
Connection Expert
EG
Posts: 42,192
Registered: ‎12-24-2003

Re: what kind of coaxial cables and splitter do I need to prevent a slow connection?



higgie wrote:
 
because it is carrying most of signals through the cable...
 

 

All. :smileywink:
Connection Expert
JamesR
Posts: 6,423
Registered: ‎09-29-2007

Re: what kind of coaxial cables and splitter do I need to prevent a slow connection?

Impressive posts!  Verbosity Rules!  If I were moderator I would make this thread Sticky to keep it near the top.  Failing that I have saved it to the Hard drive under TechStuff and have printed it out for archival purposes.
One Question, does anyone sell a powered Splitter that provides Gain rather than Loss?
 
Networking Expert
Weil
Posts: 3,567
Registered: ‎07-04-2003

Re: what kind of coaxial cables and splitter do I need to prevent a slow connection?

Radio Shack (and others) sell a 4 way two-way amplifier/splitter for about $50.  It claims to have 8 db gain for each port.  I have one and it appears to work as it currently is feeding three tv sets with digital boxes.  Again, they sell others for less that are not two way and/or are not specified for digital cable.  sam
Regular Problem Solver
Posts: 1,210
Registered: ‎04-07-2005

Re: what kind of coaxial cables and splitter do I need to prevent a slow connection?

Agreed, there are many out there, however as with any sort of signal amp (think of amps for home stereo, car audio, etc), quality makes a huge difference.
 
The amp has to be placed where it has a good signal.  If you have a lousy signal, you're just amplifying the lousiness.  You'd want to place the amp as close to the side of the house as possible, and ideally BEFORE any splitters.  Otherwise, you'll just add all kinds of noise along with the extra signal.  Sure the router may stay synched better, but you'll be having all kinds of packet loss and retransmissions.
 
Even with a good signal, a lousy amp will have the same effects.  As stated it must be bi-directional, and be able to amplify at least 1Ghz of signal.  But generic brands will put the worlds best specifications on there, but perform horribly.  Often its a good idea to find out the model that Comcast uses in your area and get ahold of one of those, they've done all the testing and picked the best one for you.  A friend of mine actually had one installed by Comcast for free (your mileage may vary).
Regular Problem Solver
Posts: 1,210
Registered: ‎04-07-2005

Re: what kind of coaxial cables and splitter do I need to prevent a slow connection?

Flush is ok too, you don't want too long (1/4" beyond the end of the connector) or too short (1/4" below the end of the connector).  Anything inbetween will be fine.

higgie wrote:
Also, make sure the center cable sticks out of the F- connector about 1/8 inch because it is carrying most of signals through the cable...
 
higgie
 



Regular Problem Solver
Posts: 1,210
Registered: ‎04-07-2005

Re: what kind of coaxial cables and splitter do I need to prevent a slow connection?

Not true, the shielding can have some great radio stations on it, some sweet EMI interference, possibly some dangerous voltage too.  Very useful stuff :smileylaugh:

EG wrote:


higgie wrote:
 
because it is carrying most of signals through the cable...
 

 

All. :smileywink:



Connection Expert
EG
Posts: 42,192
Registered: ‎12-24-2003

Re: what kind of coaxial cables and splitter do I need to prevent a slow connection?

:smileyshocked: :smileygrin: