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Questions about RG-11 and long cable runs

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Old 01-25-2008, 10:55 PM   #1
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Default Questions about RG-11 and long cable runs

I have a question about RG-11. Firstly, I know it's recommended for runs longer than 150 feet, but does it make a noticable difference when trying to reach a station at 75-100 miles with a shorter run, say of 50 feet? And I also have the option of moving my apparatus about 150 feet AWAY from my house, and onto a pond dam. The advantage of this would be 25 feet of extra height, enough to get me above the tree line. Do you think the extra cable run would cancel out any advantage the extra height would bring?
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Old 01-26-2008, 06:20 AM   #2
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Originally Posted by alphanguy View Post
I have a question about RG-11. Do you think the extra cable run would cancel out any advantage the extra height would bring?
If you use a preamp the loss of the extra cable would be overcome. You might not even need to go to RG-11.
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Old 01-28-2008, 09:05 AM   #3
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Coming from a microwave engineering background, there are a couple of ways to look at this...

You have to factor in the highest frequency you want to receive, I'll use 700MHz.

Commscope5731 (RG6, VG quality) loss for 150ft = 8.4dB
Times LMR400-75 (RG11, VG quality) loss for 150ft = 5dB

So we can predict the difference in signal strength is 3.4dB.
When it comes to most receiver installations, 3.4dB is not going to make a big difference. This is particularly true if you've got great signals already. However in my case I'm very deep fringe (100+ miles) and that 3.4dB does indeed make a difference in my case. BTW, a pedant will quickly point out that 3dB lower signal strength means that only HALF the signal is making it to your receiver.

The gain of your preamplifier is fixed and although it can certainly overcome losses in the cable and put you into solid signal area there could very well be a benefit to up-rating your coaxial cable.

I actually tested a number of different 300Ω-75Ω baluns yesterday to find the one with the lowest loss. It was a good nerdy experiment because there's quite a difference between the new one (worst) and the 1970's vintage Magnavox long one (very good) and Marsland "Magic Match" (best by far).

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Old 01-28-2008, 09:11 AM   #4
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Also you need to consider cable length not just the distance from your house. Up the tower and throught the house to your TVs sounds like it could be more like 200 feet. Also as connectors get old there will be some additional losses in the future. Good connector protection from the elements can forestall this.

Also it may be instructive to know what the cost difference the rg6 and rg11 would be.
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Old 01-28-2008, 09:20 AM   #5
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Isn't RG11 too "thick" to fit into standard F-connectors on TV's and satellite boxes? If so how to you bridge between the RG6 and RG11 cable?
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Old 01-28-2008, 10:04 AM   #6
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I tried that as well, and had problems with it fitting. I gave up on it, and my 60' of RG-11 is still in the heated shed (I'm assuming it's still good, although it's 8 years old... it's never been exposed to sunlight, freezing temperatures or moisture)... but when I switch my system over this year, I'm determined to use it, and after reading much about cable loss, I'm abandoning the idea of moving my antenna further away. I'm going to SHORTEN my run to within 60 feet. And since I'm a passive DX'er, any preservation os signal will be of utmost importance. And THANK YOU for the info about the loss in the balun. I didn't know some brands were better tha others. I also wondered... would you lose signal if you hooked your into an external tuner as opposed to directly to the set?
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Old 01-28-2008, 10:23 AM   #7
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BTW, fellows, Thomas and Betts, and several other companies make RG-11 compression fittings that will mate up with regular RG-6/RG-59 fittings: Check the Skywalker catalog and you will find them. One of the great things about RG-11, though is that it is ALL quad-shielded, and that it is acceptable for direct burial without a conduit if you choose to do so. By the way, an additional 3.4 DB signal is welcome in ANYONE'S book when you are talking about DXing!
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Old 01-28-2008, 11:29 AM   #8
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Default Fittings

My problem was that the copper conductor was too large to fit into the F conenctors on the back of my VCR, so I'm guessing that one must use some kind of adapter to get this to fit? I know where to buy the fittings for the end of the cable, but the size of the conductor is what's puzzling me.
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Old 01-28-2008, 12:11 PM   #9
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RG11 usually has a 14AWG center conductor, RG6 is 18AWG. The difference in O.D. between 14 and 18 AWG is 0.0238". If the F-connector on the back of your VCR is smaller than the spec.

The specification (PDF) for the female F-connector states that the maximum diameter of the inner conductor guide is 0.068", meaning that 14AWG (which is 0.064") may fit, but a lot is going to depend on the construction of the connector and whether you flattened the center conductor of the RG11 while cutting it. I have had to trim the center conductors with a Dremmel cut off wheel because of the burr on the end.

One thing to try is to get a barrel connector that will fit the RG11 to make the transition with. I've done that a couple of times where I was able to open the one end slightly with a drill bit by hand.

Here is a link to the connectors I think tiger was talking about. Notice they have their own 0.032" center conductor.
Thomas & Betts LRC Plenum Connector, Type F for RG11 Plenum Coaxial Cable.

Last edited by rbinck; 01-28-2008 at 12:16 PM.
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Old 01-28-2008, 12:38 PM   #10
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Quote:
Originally Posted by tigerbangs View Post
BTW, fellows, Thomas and Betts, and several other companies make RG-11 compression fittings that will mate up with regular RG-6/RG-59 fittings: Check the Skywalker catalog and you will find them. One of the great things about RG-11, though is that it is ALL quad-shielded, and that it is acceptable for direct burial without a conduit if you choose to do so. By the way, an additional 3.4 DB signal is welcome in ANYONE'S book when you are talking about DXing!
Not all RG11 is quad shielded, there are specific rg 11 versions for direct burial, plenum install, and there are copper clad and solid copper versions.

for example

Belden
1523A RG11 Broadband Cable
Duobond II 100% foil shield and 60% aluminum braid
14 awg solid copper covered steel center conductor
Sweep tested 5MHZ to 1GHz
Black PVC jacket
NEC CATV CM
1000ft spool

therefore statement is false.
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Old 01-28-2008, 12:58 PM   #11
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Oh yeah, I also wanted to add that while you can make up for 3.4 db (probably going to be more like 4 db) loss with a preamp, all preamps will add some degree of noise that the larger cable won't.
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Old 01-28-2008, 01:53 PM   #12
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Default pre amp

Well, since I dabble in DX'ing, I intend to use my RG-11, AND pre-amp. I know the titan7777 is well reccommended, but is there anyhting more high end that is even better? I don't mind spending 150 bucks or so for the thing.
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Old 01-28-2008, 02:47 PM   #13
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I have read good reports on this amp.

Sitco pa24 preamp...on uhf 25 db gain, 1.4 db noise figure. never tried it personally though.

http://www.simplicitytool.com/preamplifier.htm
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Old 01-28-2008, 03:07 PM   #14
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Does burying the cable cause any loss in signal strength?
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Old 01-28-2008, 05:57 PM   #15
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Quote:
Originally Posted by alphanguy View Post
Well, since I dabble in DX'ing, I intend to use my RG-11, AND pre-amp. I know the titan7777 is well reccommended, but is there anyhting more high end that is even better?
If you are planning to use a 7777 preamp, you have enough gain to use RG-6. If you already have the RG-11, you won't need a 7777.

The 7777 can overload, the HDP-269 is better, but has too little gain for 200' of RG-6.

There are GASFET preamps with lower noise than the 7777, but they seldom make enough difference to matter.
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