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RG6 versus standard cable (RG58?)

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Posted by: john9999

Best Buy DTV contractor is coming tomorrow. Odd question from the pre-screener that called last week. "Do you need wiring or do you already have cable?" Whaaaa? I read everywhere that RG6 is required but is souds like they are willing to use existing runs. even the sales-drone at BB says you can use existing cable "but it might overheat so don't use it if it runs through insulation."

What's the real poop, here? Must have RG6 or use existing runs of RG58? (The run for the HDVR2 needs twin wires so I'll insist on a fresh run of RG6 there.)



Posted by: Pluto01

The difference between RG-6 and RG-59 is the amount of shielding on it. RG-6 has a much better (100% I believe) shielding). So, although RG-59 'can' work, you may fall victim to signal interference and/or loss due to the lesser grade shielding. The amount of problems will be proportional to the length of the cable run (longer cable = higher chance of problems).

The 'poop' is that you really want RG-6 in the long run, and to avoid problems (better safe than sorry, etc). So if BB is coming to install, you should make them run RG-6 for both lines to the reciever. :-)

-B



Posted by: OLdDog

RG 58 is often used for scanner, ham, and CB ants I have not heard of it being used for TV or SAT in any form. But there could be cases I do not know about.

The common old cable, and cables companies still install it a lot, is RG 59.

RG6 is better and works better for SAT installs but, with short, under 50 feet, RG59 works just fine.

IF you are pulling a new wire it is not much harder, or more expensive, to pull two.



Posted by: john9999

Presbyopia got me. RG59. OK so I'll have him pull a twin cable of RG6 to the HDVR2 and leave the 59 for the other run which is about 10 feet from where the multiswitch will be.



Posted by: Bob TeaTow

Rg6 is wider and slightly more expensive than RG-59. It has lower signal loss per foot, which is particularly important for long runs of the high frequency (gigahertzish) frequencies used by DBS-satellite systems.

The "amount of shielding" explanation is not correct.

Search this board for much more fact, speculation and opinion.
If you really want "more shielding" then us "quad shielded" RG-6.

It is correct, that for short runs - RG59 that is in good condition and properly connectorized (make sure the threaded F connector is really electrically connected to the cable shielding!) will work fine. Even really old stuff. It's an urban myth that RG59 "rots" any differently than RG-6.



Posted by: Bob TeaTow

OOOOh "RG59 will overheat" is a new line of BS that I never heard or saw before. Gee any wire will overheat if you put enough current through it!
Seriously. Not a problem. Pure BS. We're talking very low power and voltage to the LNB. We're not running a high-power broadcast antenna here!



Posted by: lostcause

RG numbers refer to the diameter of the center conductor.



Posted by: phone1

quote:
Originally posted by lostcause
RG numbers refer to the diameter of the center conductor.
Huh? In what measurement? Taken literally that would make RG59 almost ten times bigger than RG6.

In any case, wire thickness is measured in gauge. RG59 has a center conductor of 22 AWG (0.6438 mm diameter), while RG6 is 18 AWG (1.0237 mm diameter).



Posted by: Bob TeaTow

I always thought the RG numbers were assigned by the US Military in a way that has nothing to do with the physical dimensions...

But maybe that is another myth.



Posted by: jahf

My installer briefly talked about keeping my existing RG59 from the wall to my HDVR2. However, when he noticed how long that run was (over 10 feet) and realized he needed to have 2 runs to support both tuners, he went ahead with 100% RG6 from the sat to the wall to the tuners.

That said, he also said my Monster Power surge suppressor switch was not going to work because even though I have 3 coax inputs/outputs, the cable input and antenna input were filtered and I only had 1 that was labelled for satellite. He recommended getting a Panamax supressor.

I tested it on the Antenna input and saw the same reception as with the Satellite input (I never tried the Cable input) so I ignored him. When I tested I removed one RG6 from the wall so that I had RG6 to the switch and RG6 from the switch.

However, after testing, since I didn't have enough RG6, I put both of the RG6's on the wall to the switch, then put RG59 from the switch to the HDVR2. Doing this my satellite signal dropped from <> 90 to <>75. Good enough to work, but I will be replacing it as I get more weather interferrence and we've had a lot of snow.

These are very short RG59 runs ... 5' per cable. I definitely wouldn't recommend using any longer runs of RG59, especially on an HDVR2 since you have 2 cables next to each other and need to prevent crosstalk. It might be less of a deal with a single cable.

Definitely don't use RG59 outside if you are running more than 1 line ... at least in my case I have 3 runs of about 60' from the sat to the front of the house, all stapled direclty next to each other. RG59 would have some serious interference issues at that point.



Posted by: Bob TeaTow

More facts, less BS:

http://svconline.com/ar/avinstall_h...cable/index.htm



Posted by: OLdDog

quote:
Originally posted by phone1
Huh? In what measurement? Taken literally that would make RG59 almost ten times bigger than RG6.

In any case, wire thickness is measured in gauge. RG59 has a center conductor of 22 AWG, while RG6 is 18 AWG.

RG 6 = 6.0, RG 59 = 5.9 and RG 58 = 5.8 in 1/100s of an inch - I believe.



Posted by: Bob TeaTow

Okay, no BS this time. Belden is a very good cable company

http://bwcecom.belden.com/college/t...pplications.pdf

RG-xx are old US Military specs which cover a number of dimensions.
The crucial dimensions of any coax cable are the conductor diameter AND the dielectric diameter == the inner diameter of the shielding AND
those together with the velocity of propagation of the dielectric DETERMINE
the characteristic impedance of the cable -- eg. 75 ohms for both RG6 and RG59.



Posted by: Bob TeaTow

From the above Belden doc
quote:
RG, or Radio Guide, is the manner that the
military used to identify transmission lines. The
RG number specified the physical construction,
materials, physical, mechanical and electrical
requirements of the cable. This methodology is
now obsolete and the military has changed to
“slash sheets” for identification. For example,
RG-58C is now M17/155-00001 or M17/28-
RG058. Today, the RG number has become a
generic identifier, telling the user of it’s general
construction and electrical properties, but not
specific enough to compare attributes from one
product to another.




Posted by: phone1

quote:
Originally posted by OLdDog
RG 6 = 6.0, RG 59 = 5.9 and RG 58 = 5.8 in 1/100s of an inch - I believe.
Arghhh... just do the math or look it up. By your terminology, RG6 should really be called RG60 and there would be only 1/100 inch difference between the two. The facts:

RG6 - (18 AWG) 0.0403 inches
RG59 - (22 AWG) 0.0254 inches

:rolleyes:



Posted by: ourmusic

The difference in cable types and quality as far as what we need it for has to do with the amount of signal loss.

We are working with ultra high frequencies when sending signal from the dish to the receiver. The idea is to keep the loss of signal to a minimum and still have a good impedance match.

Rg59 cable has more signal loss than rg6. I have used rg11 at times and had even less loss of signal, but it is large and can be a pain to work with.

By the way, having less loss of signal from the dish to receiver, will reduce the problem of rain fade.

As for having a fire with rg59, that would more likely be a problem if we were using a high power transmitter and not receiving equipment.

As is usually the case, the sales person doesn't know anything about what they are selling. :(



Posted by: doconeill

quote:
Originally posted by OLdDog
RG 58 is often used for scanner, ham, and CB ants I have not heard of it being used for TV or SAT in any form. But there could be cases I do not know about.


RG58 is 50 ohm coax typically used in "thinwire" (10base-2) Ethernet. Much of that has been replaced nowadays with much-cheaper-and-easier-to-deal-with twisted pair cables, but I'm sure if I head back to the University I used to work at, I could still finds some.

The one nice part of it was the bus-type daisy-chaining that allowed you to use a single cable run for multiple computers.

What I really hated was when the media lab guys, thinking any coax with BNC connectors was good enough, snuck RG59 into the chain. Weird things would happen, like you could have a "black hole" for data, where systems near the RG59 segment wouldn't work, but systems at either end of the segment would work fine.



Posted by: DNERO2004

Heres the fast answer. Get the RG6.



Posted by: Combat Medic

Actually you'd be best off with LMR-600 from http://www.timesmicrowave.com/ :-)

-Mike



Posted by: steuert

As you can see from this thread, it's easy to get carried away with this subject. If you get a signal strength of 80 or so with the existing RG-59, no need to replace it with RG-6, and no need to look up and compare a bunch of specs to help make up your mind.

If signal strength is much lower than this, you would probably be better off with RG-6, and I would certainly use RG-6 for new work. Keep in mind that with a digital satellite signal, any signal you receive will be of perfect quality (unlike analog broadcasts.) The only difference is that a weaker signal will be more subject to rain fade.



Posted by: HofstraJet

quote:
Originally posted by Bob TeaTow
More facts, less BS:

http://svconline.com/ar/avinstall_h...cable/index.htm



Interesting link. Thanks. I was especially surprised to see how poor S-video cables are and the price we pay for their supposed convenience.

Should we send a copy of this article to Monster Cable? :D



Posted by: ourmusic

In reading the article, I noticed that when he talked about extra shielding that he would always refer to loss of signal.

The main reason for extra shielding is to prevent other RF signals from 'bleeding' in and causing problems. There is a reason for quad shield on cable systems to help prevent interference from local transmitters in the area.

As for attenuation, it is best to have the largest possible center conductor (wire) to reduce loss.

I have several cables that claim to be RG/6. One is almost thin enough to be RG/59 cable and another is almost thick enough to be standard RG/11.

The type of shielding the cables have is one of the reasons for the size.

The center conductor is a different size on the cables I have.

Bottom line is, if you want the least amount of signal loss, the best performance and the least chance of rain fade and other problems, use the BEST quality cable and connectors you can get.

The largest center conductor possible and with a good amount of shielding and the ability to handle the types of weather conditions you will most likely have in your area.




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