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Coaxial Cable Question

14K views 9 replies 5 participants last post by  JamesA 
#1 ·
Hi everyone,

I've got a bit of a signal problem for my cable television in the house. I called the cable company and they came out to the house to take a look. From the street, they said that the signal quality was fine. They claimed that the problem was that the house is wired with RG59 cable. Their suggestion was that I should rerun it with RG6 cable, which they would be happy to do for me for an extra fee (which seemed pretty high to me).

A few things that may or may not be important about my house:
1 - There are three televisions in the house; 2 of them have cable boxes.
2 - There is also a high speed internet connection (which is cable based).
3 - I have VoIP phone in the house, so it runs over the internet connection, which is cable.
4 - Probably the longest run of cable is about 80 or 90 feet.
5 - The house is 23 years old, and the cable has probably never been replaced since the building of the house.
6 - The house has two stories - one of the hook ups is on the first floor, the other two are on the second.
7 - There are three splitters in the house: one on the outside of the house (not sure where the other two cables go, but one goes inside the house), one under the house (where the lines to the TVs and high speed internet connection go), and one from the wall (which splits the cable between the high speed internet connection and a television in a room).

So a few questions for you guys:
1 - Is there really a signal quality difference between RG6 and RG59?
2 - How hard would it be to run new cables? That is, take out the RG59 and put in the RG6. Ideally, I'd like to keep the lines running where the old ones are now. That is behind the walls.
3 - Any suggestions on how to actually run the lines? Especially the ones to the second floor?
4 - Outside of RG6 specification, is there anything special that I should be looking for when I buy the new cable?
5 - Would the splitters need to be upgraded as well or will they be able to handle the new cable? How about the wall jacks?

I know that was a really long post, thanks for getting through it! Thank you for any help that you can give me!

Phil
 
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#2 ·
1 - Is there really a signal quality difference between RG6 and RG59?
RG6 just has heavier shielding to resist interference, I would change the cable only after first checking your splitters, each split degrades the signal. Then maybe try a booster, Motorola has one for like $50 at any electronics store.

2 - How hard would it be to run new cables? That is, take out the RG59 and put in the RG6. Ideally, I'd like to keep the lines running where the old ones are now. That is behind the walls.
Are they secured inside the wall? Otherwise just tape the old to the new and snake away. You may want to setup a central "AV center" and maybe even pull ethernet while you're at it for a home network? Or speaker wire for audio? I always try to think ahead when I'm rewiring...

3 - Any suggestions on how to actually run the lines? Especially the ones to the second floor?
I thought you were just replacing the existing ones? Otherwise a snake will do the trick (and some patience)

4 - Outside of RG6 specification, is there anything special that I should be looking for when I buy the new cable?
For your application I'd say no. Have you thought of upgrading to digital cable? You'll have to rent a box for each TV, but you'll have no quality loss

5 - Would the splitters need to be upgraded as well or will they be able to handle the new cable? How about the wall jacks?
If they're old, replace them. Every connection degrades signal, every split causes a loss. It's a "weakest link" situation...
 
#3 ·
I'm going to beg to differ with part of the reply from Johnny331.

There is a HUGE difference between RG59 and RG6. Resistance values and bandwidth are but two of these differences.

That said:

It's hard to follow how the cabling is run by your description. I assume:

1. One splitter outside with one line going under the house and one line going up stairs?

2. A splitter under the house taking that one line from outside and sending it out to 2 0r 3 locations?

3. A splitter in the room where a TV and the VOIP/Modem is located?

If that's right:

You should be fine with the existing RG59.

What you will need is a bi-directional RF amplifier. I would say something like the Channel Vision CVT-2/8PIA II with a CVT-P1 power injector should be at the head end (cable demarc outside). This device would be your ONLY splitting device!

Note: Do not purchase a low end amplifier from Radio Shack, or some other outfit, it will not get the job done. And in all likelyhood will make matters worse.

Then ALL coax runs should be home run from this amplifier (NO splitters downstream from this point).

Meaning you should run run new cables under the house, eliminating that splitter. and you should run a new line in from outside to the VOIP/modem (although you may be workable without that last new run of coax).



I'm not all that surprised that the cable company is blaming the cable in your house. They're looking to drain you dry. That's what they do...:yes:

In my area, Time Warner will furnish an amplifier when needed (IF the customer complains enough). And in your case an amplifier is the fix.

I doubt that you'll need to worry about the second floor, even though there is probably a downstream splitter there as well.

If your signal strength from the street is within acceptable limits (FCC requires +7db at 7" from structure) the loses of all those splitters is what's doing you in, not the low grade coax.

Hope this helps....
 
#4 ·
Thanks!

Johnny and KT, thanks for the quick replies! Just a few points of clarification.

Johnny - If I am understanding your suggestion, you are thinking that I should first see if I can minimize the number of splitters, then if that still has a problem, I should consider upgrading to RG6. And your suggestion for wiring the RG6 is to pull the RG59 cable out of the wall a little, tape the end of the RG6 (electrical tape, maybe?) on to the end of the RG59, then go to the other end of the RG59 and gently pull it through, right? Makes sense.... (And while I'm at it, I could also pull some Ethernet cable through too. Again, great idea!) I've definitely got a few ideas from you. Thanks so much!

KTKelly - You seem to think that the RG6 would make a big difference, but for my little set up, might be a bit of an overkill, right? (Your three assumptions on the set up of my house were basically right...) However, that being said, you seem to think that I should also try to minimize the number of splitters. In looking at your suggestions, I think that I might already have what you were refering to. Outside of the house, I have the following:

On one of the TVs inside the house, I have the following (it goes only to one television):

I think that the first pic (which was in place when I bought the house) is what you described as the bi-directional RF amplifier, right? The second pic (which I actually got from Time Warner Cable) is what you warned me not to get, right?

So, if I am understanding you properly, I've got all of the hardware that I need, but probably just too many splitters. Does that sound about right?

Again, thank you two so much for your input. If anyone else wants to weigh in, please feel free.

PS - One last question, I promise. I ran into a similar problem about a year ago. Back then, Time Warner came out and gave me the hardware from the second picture listed above. Could there be anything else in the equation that would degrade the signal over a year? Thanks!
 
#5 ·
Phil,

The first pic is a bi-directional amplifier, and the second pic is a power injector. So the cable company gave you what you needed, at that time.


A problem I see there is that they installed a four port amplifier, with one port being used for the power injector, so there are only three outputs available for your use.


Now my questions are:

Are all ports on the amplifier in use?

Where exactly are the existing splitters? And are they 1x2 splitters?


Rest assured, the RG59 is not your problem. I'd bet that if your system worked after the cable company installed that amp, that you now have some build up on the various connectors and splitters. If you were to install new splitters and new ends on the cable lines, your problems would most likley go away. At least for some time....:yes:
 
#6 ·
I think you need special equipments to do the job right:

- measuring signal device
- making connector device

These are small devices, but you don't have them, you don't have them... those cheap equipment from HD cannot do the job ....

so you probably either spent a lot of $$ to get the good quality equipment to do the job yourself... or have no choice to pay someone to do it....

the cable core wire the thicker the better... (heard from my friend who work for cable company)...

the signal to internet should be from the line with strongest signal and do not split.... not any line can be used for internet....

tv lines is more forgiving....

I said if the cost is not sky high... you may be better off eat it and have it rest to the ground.... as your situation is complicated enough to justify the charge...
 
#7 ·
I think you need special equipments to do the job right:

- measuring signal device
- making connector device

These are small devices, but you don't have them, you don't have them... those cheap equipment from HD cannot do the job ....
It's always best to have a good meter when designing a RF distirbution system, but even the average cable installer doesn't. You'll find that only the most senior techs from the cable company might have something like a Leader field strength meter.


That said, there is a way you can get a good idea of what you signal strength is. And that's the key to designing the system properly.

If you purchase several 1db attenuators (10 or so, they are cheap) you can use them to determine the starting signal strength.

1. Disconnect all but thincoming line at the demarc.
2. Connect a short jumper to a small TV at that location and check the picture quality.
3. Install attenuators one at a time, checking the picture quality after each is installed. When the picture quality becomes "snowy", you have found the starting signal strength (adding the number of attenuators).

So now you have the signal strength at the demarc. Let's say it's +7db.

1. A 1x4 "passive" splitter has a insertion (loss) of approximately 7db.
2. RG59 has a line loss of approximately 11db per 100' (the longest run).

You now know a 20db amplfier will give you a signal at +3db (roughly) at the end of the longest run.


core wire the thicker the better... (heard from my friend who work for cable company)...
Actually it would be closer to say, the thicker the dialectric the better. But even that is sort of off the mark. Ask "friend if he uses CCS or CCA coax, percent of sheild and what the loss value is. I bet he might know the first, possibly even the second but will have no idea of the third.

cable internet should be from the line with strongest signal and do not split.... not any line can be used for internet....

tv lines is more forgiving....
Not even close.....:no:

if the cost is not sky high... you may be better off eat it and have it rest to the ground.... as your situation is complicated enough to justify the charge...

Lost me on that one....:huh:



Yes, there are a large amount of variables that can come into play, but with this small system, it shouldn't be all that difficult to DIY.

If you do some research, you will find that the loss levels we (in the industry) use are the worst case numbers for OTA. Low channels (400mhz) will have less loss than much higher (900mhz) channels.

I do a LOT of RF distribution in my business....

My two rules?

1. No downstream splitters ever.

2. Equalize ALL input signals.

Rule #2 doesn't apply in this case.
 
#9 · (Edited)
"It's always best to have a good meter when designing a RF distirbution system, but even the average cable installer doesn't. You'll find that only the most senior techs from the cable company might have something like a Leader field strength meter."

not true... all the guys from cable company come with a small digital device which tells the signal... don't know if this is the top of the line euipment you are talking about... but somthing like that is a standard device cable guys carry around...


if the homeowner willing to go that far to tackle this issue... why not.... me... I found it so headache just to make a connector out of the troublesome coaxile cable... never made one I like so far... using the the cheap HD coaxile crimper.... not to mention to go through all these headache.... but you are right... if I don't have a friend in the industry... I probably also very reluctant to pay expensive $$ for someone to come over to fix it rather than trying it myself....

"Could the problem be that I crimped poorly?" Definitely... that is why you need the cable company equipment... it is not a rocket science equipment they have... but you just couldn't buy those with twenty thirty bucks.... may be hundred bucks....
 
#10 ·
A possible, simple solution

I had some issue a while back with cable internet signal strength. The tech came out and ran some tests with his signal strength meter.

He showed me a real simple thing that a lot of people seem to miss. disconnect all your cable connections and look into the connector. The white insulation that is around the center copper wire should be flush with the bottom of the connector where the copper wire sticks through the hole.

He explained that this, like network cable, exposes the signal to outside interference and can seriously degrade your signal. Since this is so simple, I would check this first. It may save you a lot of time, money and effort.:thumbsup:
 
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