Coaxial cable

[nizak]

Is there any performance difference between RG6 and RG6 Quad Shield?

Does the box store cable perform as well as what would be provided by say Charter for example.

It all appears to be 18 gauge.

Thanks

 

[LarryFine]

Quad shield is overkill.

 

[Geber]

Is there any performance difference between RG6 and RG6 Quad Shield?

Does the box store cable perform as well as what would be provided by say Charter for example.

It all appears to be 18 gauge.

Thanks

What is Charter? Is that a brand of cable, or the name of a cable TV company? Is the application cable TV or something else?

Can't say I have much experience testing cable; usually I just transmit into a dummy load and measure power at the near end and far end, plus check the SWR.

 

[Speedskater]

RG6 is an ancient generic label. All it indicates is that the cable has a nominal 1/4 diameter and a 75 Ohm Radio Frequency Characteristic Impedance. There are many different RG6 coax cables optimized for different parameters. Some are good at low frequencies and others are good at cable TV frequencies. A heavy braided shield at low frequencies and a foil shield at cable TV frequencies.

 

[zbang]

"Preform" is too vague a word. If you're roping a house for cable TV, any decent quality 75ohm cable and matching connectors will do the job; the runs won't be long long.

Charter is one of the large cable TV companies, and seems to get all the respect they deserve .

 

[LarryFine]

The last time I looked, the cable company's coax had one layer of at best 75% braid coverage, no foil.

 

[electrofelon]

I will say that in the late 90's I helped a friend out pulling new RG6 quad to replace non quad cable and it definitely made a difference. So I have always preferred quad, buy may e today with digital and what not it doesn't matter as much

 

[curt swartz]

The last time I looked, the cable company's coax had one layer of at best 75% braid coverage, no foil.

Even in the 80's cable companies used RG59 with foil and at least 1 braid. I can't imagine any of the using an cable with less than 100% shielding.

If you tried to use a cable with less than dual shield (foil & braid) today your service will get cut at the tap very quickly.

RG6Q is over kill for most areas but has become a common standard for most LV contractors. Most cable companies use dual shied or tri shield RG6.

 

[LarryFine]

Even in the 80's cable companies used RG59 with foil and at least 1 braid. I can't imagine any of the using an cable with less than 100% shielding.

If you tried to use a cable with less than dual shield (foil & braid) today your service will get cut at the tap very quickly.

I should have said that this was the underground cable feed to a house.

It had coverage equal to or less than this cable, and no foil shield. I looked at it closely.

 

[hbiss]

The reason for cable shielding is twofold. First, it has to be sufficient to keep the RF from leaking out. Cable companies are required to monitor "leakage" because some of the frequencies they use are the same as those used over the air for such things as aircraft navigation and emergency communications services. Insufficiently shielded cable and poorly installed connectors allow the cable signal to radiate like an antenna and jam the over the air signals. Cable companies face stiff fines if they are found in violation of leakage levels.

Second, cable systems can be thought of as operating in duplex mode. Data is sent to you but it also has to send data back from you to them. Certainly, this can be understood for internet, but it also applies for TV and phone service. The cable boxes and modem constantly send data back to the cable company and this is why the same system integrity needed to prevent leakage is needed to prevent interference (called ingress) from entering the system and disrupting the return channels.

Cable companies have adopted their standard cable that they tested to meet leakage and ingress and that depends on the location of the system. Quiet locations can get away with an RG6 that has a foil shield covered with a 100% braid. That would be minimum. If you are in an RF noisy urban area and particularly those near transmitters you need to up the shielding to stop ingress, and quad shield may even be required. But I will agree that QS is overkill in most instances.

The good news is that fiber to the premises and Ethernet within the premises is replacing coax as streaming is becoming more and more popular.

-Hal

 

[CurrentFlow]

I recommend using RG6Q with Compression Connectors for best performance especially if you are using the coax to connect to a modem. Terminate all unused ports on a splitter/combiner etc with a 75ohm F connector terminator. RG59 is way too leaky and will underperform if used for anything other than connecting to a tv antenna. If it is a long underground span use RG11.

 

[LarryFine]

RG59 is way too leaky and will underperform if used for anything other than connecting to a tv antenna.

Isn't RG59 50 ohms? I use an all-copper (not clad) RG59 for the five RGB-HV signals to the CRT projector in my home theater. I use analog component video, and a transcoder to drive the projector.

 

[hbiss]

RG59 is way too leaky and will underperform if used for anything other than connecting to a tv antenna.

RG59 comes in many of the same shielding variations as RG6. But the problem with RG59 is that it's loss makes it impractical for use at cable frequencies. Check the loss between RG6 and RG59 at 1Ghz and see for yourself.

-Hal

 

[hbiss]

Isn't RG59 50 ohms? I use an all-copper (not clad) RG59 for the five RGB-HV signals to the CRT projector in my home theater. I use analog component video, and a transcoder to drive the projector.

No, RG59 is 75 ohms. Your application is baseband video that doesn't exceed 6Mhz and that is where RG59 with a solid copper center conductor and copper braid shield has always been used.

RG58 is 50 ohms. One use is for CB and other low power transmitter connection to the antenna.

-Hal

 

[infinity]

IMO you don't need quad shield. I've even used copper clad RG6 without any issues.

 

[egnlsn]

I always use Series 59 cable for jumpers. At 10', the difference is ~1.5dB, and 59 being more flexible than 6, it's lower profile and looks better. The construction's the same - same shielding, same bandwidth, etc.

 

[Craig Maes]

In a previous life I was a CATV engineer. Quad shield cable has its place in urban areas that are close to television transmitters. We had tremendous issues with signal leaking into the cable, especially when we could see the transmitter tower from the customer’s house. Quad shield and non-quad should have the same loss properties. I would always wire a house with RG6 not RG59; same labor but the loss could just make the difference, especially if they have many outlets. Leaks in the cable (out or in) are caused by impedance mis-match, which is caused by improper connector installation or improper "hammering" the cable with staples. Impedance mis-match used to also cause ghosting in the analog days before everyone went 100% digital.

 

[cabledawg]

IMO...For residential, most RG6 will do. Just get a decent Compression tool(like 45$) or so and some compression fittings and a good quality strippers.

 

[25yrApprentice]

ok, lots of misinformation to clear up. No offense fellas.

1. RG59 has higher loss over long runs, no longer used except for connecting a cable box video output to an older tv under 6 feet.
2. RG59 with copper braid is used for analog surveillance cameras.
3. Quad shield has mid level loss compared to standard dual shield RG6, but is better for running near sources of interference (think plenum drop ceilings in commercial buildings running next to fluorescent lights, electrical wires and WAPs).
4. Only cheap chinese RG6 and RG59 copper braid has no foil. UL listed RG6 used in cable plant transmission and satellite tv etc is dual shield, has a layer of foil on the outside of the dielectric, followed by a certain percentage of aluminum braid (good stuff is typically 70%, but only american brands like belden actually meet their own spec).
5. Don't use metal staples on coax (or cat5/6 for that matter). It causes frequency trapping. Use coax screw clips. Pinching the dielectric foam changes the frequency response.
6. Coax used for underground does not need to be quad shielded due to the earth's absorption of rf unless it is buried in the same trench as an electrical run. The jacket of the underground run is the important factor, requiring a direct burial rating, which is water proof (yes standard polyvinyl can absorb water over time and will rust the braid causing intermittent connection) and is typically filled with a substance that coagulates if the jacket gets nicked during installation
7. There are two flavors of center conductor, solid copper, and copper clad steel. Solid copper is the best. However, the cost of solid copper RG6 will be basically the same as copper clad RG11, so if you have a run that is over 200', use RG11 copper clad steel, otherwise RG6 ccs is fine unless you're running high frequency services like satellite tv, or voltage carrying services like microwave radio.
8. Never use hex crimped F connectors. Almost all problems with coax are a result of poor terminations and cheap barrels. If you cut the cable with side cutters, roll the end in your fingers to make the end round again. Use the proper coax stripper, make sure the dielectric is cleanly cut and flush with the base of the connector, watch for straggler braid wires wrapped around the center conductor, leave the foil intact (not crushed), gently fold back the braid in a circular motion, use the proper sized f connector... should slide on correctly, if using quad shield make sure to use quad shield connector (more room for shielding), if using plenum use plenum connector (tighter tolerance for thinner jacket), if using direct burial the braid will be sticky so be patient, dont ruin the foil, bring a wet wipe for your fingers and use a tee press . Lastly, cut the stinger (part of the center conductor that protrudes past the end of the f connector) to 1/4". No hypodermic needles, it screws up the barrels. When compressing, make sure the connector compresses squarely. Visually inspect the inside of the finished termination. If you screw up, cut it off and try again, it happens to the best of us.

Any questions?

 

[hbiss]

ok, lots of misinformation to clear up. No offense fellas.

Haven't seen any, except for some things you said.

5. Don't use metal staples on coax (or cat5/6 for that matter). It causes frequency trapping. Use coax screw clips. Pinching the dielectric foam changes the frequency response.

Staples? That's not true, they are fine. But yes, anything that deforms the cable will cause problems. Preferably use insulated staples (because the plastic won't damage the cable) and don't sock them down. Stay away from staple guns, but sometimes you can't when you are doing exposed work. At least use the proper size staple and don't sock them down either. You should be able to slide the cable through the staple to show that it hasn't been compressed.

7. There are two flavors of center conductor, solid copper, and copper clad steel.

Rule is that copper clad steel is economical for anything that isn't carrying power. For SAT dishes, etc. where the cable carries power also, always use a cable with a solid copper center conductor.

The jacket of the underground run is the important factor, requiring a direct burial rating, which is water proof (yes standard polyvinyl can absorb water over time and will rust the braid causing intermittent connection) and is typically filled with a substance that coagulates if the jacket gets nicked during installation

The jacket on direct burial cable is polyethylene (like sprinkler pipe) as opposed to PVC. Direct burial cable is filled with a flooding compound, variations look like grease, goo, etc. The flooding compound keeps any water that might enter through a nick or cut in the jacket from entering the cable or, if it does, from migrating along under the jacket. No, it does not coagulate.

Flooding compound is used on other direct burial communications cable such as multi-pair telephone OSP cables. Interesting to note that it's one of the reasons that the Code limits the length of OSP cables in buildings. The flooding compound is flammable and underground cable is required to go directly to a terminal in the building that has a steel compartment with a cover for the pairs to be punched down.

Keep in mind also that direct burial cable needs to be used in buried conduit and ducts as they are considered wet locations.

I agree 100% with your #8. Connectors are the most important yet misunderstood part of this work. Always use compression connectors, always use the right connector for the cable you are using, always use the right tool for the connector and prepare the cable properly. There is no such thing as a "universal" connector!

-Hal