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Old 11-24-2013, 11:22 AM   #1
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How to check cable signal strength


Hi all --

I just spent an hour in hour crawl space and was able to reconnect a long unused coax/cable outlet to my Comcast input.

However, the coax cable was slightly rusty at the end (it had been sitting loose under the house and the cable appears to be 15-20 yrs old. I would just put in a new cable, but the wiring was really tight and would be a pain to re-fish.

Miraculously, the picture came in fine on my TV, but flipping my TV input back and forth between this outlet and a newer outlet, I sense a subtle decrease in picture quality. But it may just be my mind! So my questions are:

1) Is it possible that an older, slightly rustier cable provide a worsened signal?

2) Is there any way to test this on a DIY basis?

Thanks!
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Old 11-24-2013, 01:01 PM   #2
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How to check cable signal strength


1) Is it possible that an older, slightly rustier cable provide a worsened signal?
Not only possible, but highly likely.

2) Is there any way to test this on a DIY basis?
Yes, but the meter will cost $200 or more.

Common causes of strength loss are longer runs than necessary (excess cable coiled up), un-necessary connections in cable, corroded connections, and splitters.

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Old 11-24-2013, 01:02 PM   #3
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How to check cable signal strength


http://www.homedepot.com/s/Signal%25...20meter?NCNI-5

Why not just cut the end and install a new connector?
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Old 11-24-2013, 03:15 PM   #4
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How to check cable signal strength


If the cable is that old, it's most likely RG59. That is reason enough to maybe replace it with RG6.
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Old 11-24-2013, 04:54 PM   #5
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How to check cable signal strength


If your cable is showing signs of rust, it is Copper Clad Steel. It needs to be steel core. As for checking signals, you can either use your Cable modem, or the diagnostics screen for your DVR or Set Top box or DTA.

Personally I would call Comcast in about the issue, and have them terminate new ends, on all new runs of Solid Core Copper wire. DirecTV uses this http://www.amazon.com/Perfect-Vision...ds=directv+rg6

When you pull it, do a home run to a Utility room, along with two runs min. of Cat-5e from each location. Run two runs of RG-6 to the outside, where the coax will enter the building. Also make sure that it is properly grounded to the ground rod, when you have Comcast come in and put on the fittings.

Now of course you could do the fittings yourself, but they have the testing equipment to check for proper signals, when they are done putting the fittings on.
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Old 11-24-2013, 06:15 PM   #6
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How to check cable signal strength


Hey folks -- thanks so much for these answers, which confirm how little I know about wiring.

I looked up RG59 vs RG6 and I couldn't tell which one I have. The cable is actually a twin cable with two coaxes attached together. I'm only using one. The house (which I am renting) is also wired for DirectTV which I don't use, so I may be able to repurpose one of of those cables if they are state of the art RG6s.

That's great advice about using the cable box to check the signal. Looks like a little internet digging will show me how to do this.

The advice from Greg:
Quote:
When you pull it, do a home run to a Utility room, along with two runs min. of Cat-5e from each location. Run two runs of RG-6 to the outside, where the coax will enter the building. Also make sure that it is properly grounded to the ground rod, when you have Comcast come in and put on the fittings."
is fascinating, but is beyond my paygrade. Is this "to code" installation, or a way to test signals?

Overall, it sounds like this is worth a $50 visit from Comcast, if only to learn what the heck is going on here.

Many thanks!!
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Old 11-26-2013, 07:22 AM   #7
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How to check cable signal strength


Let me in on this since this is what I do for a living.

1) don't use solid copper. Use copper clad. Three reasons are cost, strength, and the skin effect.

2) in almost all cases, 59 cable is fine. The problem people run into is poor shielding but some brands of 6 are pretty bad as well. As long as there is a layer of foil and a good lawyer of braid, you're fine.

3) are you looking at digital channels? If so then you're either getting the same quality that leaves headend or you receive nothing at all. You also don't want to compare SD to HD.

4) the cable you describe is ran by satellite companies typically. Twin pair.

5) a corroded fitting changes impedance which does affect signal. Changing fittings are a very common fix to most problems.
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Old 11-26-2013, 08:19 AM   #8
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How to check cable signal strength


Tongle, why did everyone move away from RG59 if it is fine like you say?
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Old 11-26-2013, 08:40 AM   #9
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How to check cable signal strength


Here is a good blurb on it....

To summarize....RG59 would actually work as well or better for an antenna feed (less loss). But for Satellite...RG6 is better.....though, RG59 will also work.

I agree that replacing the connectors would most likely solve any 'rust' issues....but....you need the right connectors.....and I have not been happy with the garbage that HD or Radio Sh!t carries.....in the twist on flavors....

Now, if you have a coax crimper....that is the good way to go.

http://www.milestek.com/blog/index.p...x-vs-rg6-coax/

Quote:
The first obvious difference between RG59 and RG6 is the diameter of the cables themselves. Standard RG59 coax has a 20 AWG copper center conductor and RG6 coax has an larger 18 AWG copper center conductor, offering higher bandwidth and longer distance capability.

Generally, RG6 is widely used in CATV and Satellite DSS applications and RG59 is used for in analog CCTV or baseband video applications. RG6 Dual or Quad Shield shouldn’t be utilized for baseband applications, such as video projectors, component video, plasma TV’s, etc. It may sound like a great solution because of all the layers of shielding, but RG6 Dual and Quad Shield don’t have the proper type of shielding for the above described applications. It is manufactured using foil shields and braided aluminum shields. The makeup of the shields differs between models. The effective range of operation for foil shields is above 50MHz, which makes them perfect for rejection of radio frequency interference, or RFI, that may have an effect on satellite or cable installations. At frequencies below 50 MHz, however, foil shields are not effective. The braiding on the RG6 Dual shield and the RG6 Quad shield doesn’t have enough coverage to work effectively with baseband applications.

The frequencies that are used in High Definition are usually around 37 MHz. For those lower frequencies, an RG59 with a 95% all-copper shield is designed to block RFI inclusion at base band frequencies. Because RG59 does not have a foil shield, it shouldn’t be utilized for satellite feeds or cable feeds.

RG59 has a little less signal reduction, or attenuation, over 100 feet. The shielding on RG59 does not work quite as well to maintain Gigahertz level signals inside of the center conductor. RG6 has a better design for maintaining the signal levels inside the center conductor. This is the reason RG6 has become the standard for broadband CATV and satellite systems. A basic rule of thumb is to use RG6 for any Rapid Frequencies, and use RG59 for video frequencies. RG6 has an aluminum braid and an aluminum shield. RG59 comes with a copper braid, and in some instances, an aluminum braid and shield, although this is quite rare.
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Old 11-26-2013, 08:51 AM   #10
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How to check cable signal strength


Better attenuation and more durable. With that said, if the shielding is correct, then you generally leave it alone inside the house. The exception is the drop due to distance. The only time you'll benefit from changing existing 59 to 6 is if you're already running on the edge with signal or if its defective. If it's a signal thing, it is much simpler to do what I'm already supposed to do and make sure the levels are fine out of the tap and making sure the drop isn't excessively attenuating. Last resort is a house amp. Most 59 in my area is behind walls and we do not work in those spaces. If the wire is defective then obviously the only fix is to run a new one either through an exposed basement or along the exterior.

I guess what I'm saying is that its pointless to replace 59 (in house) unless it actually is causing a problem. New work should be 6 of course just for the added cushion, but ripping walls apart to replace good 59, that is causing no problems, makes no sense.

FWIW we run MOCA over 59 prewire with no ill effects.
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Old 11-26-2013, 09:02 AM   #11
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How to check cable signal strength


Tongle....where do you guys get your screw on connectors?

When the cable guy was installing our coax for internet, he had some real nice screw on RG6 connectors. I have not found some as nice....and beefy...
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Old 11-26-2013, 09:05 AM   #12
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How to check cable signal strength


Quote:
Originally Posted by ddawg16 View Post
Here is a good blurb on it....

To summarize....RG59 would actually work as well or better for an antenna feed (less loss). But for Satellite...RG6 is better.....though, RG59 will also work.

I agree that replacing the connectors would most likely solve any 'rust' issues....but....you need the right connectors.....and I have not been happy with the garbage that HD or Radio Sh!t carries.....in the twist on flavors....

Now, if you have a coax crimper....that is the good way to go.

http://www.milestek.com/blog/index.p...x-vs-rg6-coax/
That quote is off a lot. HD can be ran 55mhz and higher. The return path is 5-42mhz, so you're obviously not going to put a forward signal in the return. That quote also generalizes the shielding of 59 incorrectly. Most 59 I come across is aluminum foil and aluminum braid. The real old 59 only comes with copper braid. That is the type that loses a hell of a lot on the high frequencies. Braid=low freq shielding and foil=high freq shielding. It still needs to be at least 60% braid coverage though so keep that in mind.
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Old 11-26-2013, 09:08 AM   #13
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How to check cable signal strength


Quote:
Originally Posted by ddawg16 View Post
Tongle....where do you guys get your screw on connectors?

When the cable guy was installing our coax for internet, he had some real nice screw on RG6 connectors. I have not found some as nice....and beefy...
I dont know where exactly we get ours but the manufacturers we used were Thomas&betts , and times fiber. I think eBay has them. Even Lowe's does. They're called compression fittings.

Also forgive my poor formatting here. On my phone.
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Old 11-26-2013, 11:34 AM   #14
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How to check cable signal strength


Quote:
Originally Posted by Tonglebeak View Post
Let me in on this since this is what I do for a living.

1) don't use solid copper. Use copper clad. Three reasons are cost, strength, and the skin effect.

2) in almost all cases, 59 cable is fine. The problem people run into is poor shielding but some brands of 6 are pretty bad as well. As long as there is a layer of foil and a good lawyer of braid, you're fine.

3) are you looking at digital channels? If so then you're either getting the same quality that leaves headend or you receive nothing at all. You also don't want to compare SD to HD.

4) the cable you describe is ran by satellite companies typically. Twin pair.

5) a corroded fitting changes impedance which does affect signal. Changing fittings are a very common fix to most problems.
The reason they change the fittings on connections, is due to using Copper Clad Steel, and that there are tech's that do not know how to terminate them properly.

As for skin effect, it has nothing to do whether the cable is CCS or solid Copper core. Also RG-59 is only good for short distance patch cords, not for long runs through homes, also never ran from the pedestals or poles to the structure.
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Old 11-26-2013, 11:41 AM   #15
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How to check cable signal strength


As stated, Your Cable Modem and/or DVR or STB diagnostics menu can be used to determine signal strength. As for the tech fee, some techs may wave it, depending on the circumstances. If you have an older box, they may wave the fee for installing it, due to have line quality issues.

Same goes with if you have digital phone through Comcast, they will usually wave the fee, if having service issues with that.

Now over your pay grade, would be asking you to build a computer, to install Smooth wall, just so you can see the modem stats on a graph.

A third party that has UVerse, designed a software program for those users, to help diagnose their problems, but as far as I know, no-one has done the same at least like U-Verse Realtime, for the CATV EMTs & cable modems, so you are left doing it with the equipment, not software that you can run on your computer.

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