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Author Topic: RG-213/U coax?  (Read 1313 times)
CRBOWERS
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« on: May 15, 2003, 05:42:11 PM »

I'm planning how to setup my equipment when I get it and came to my antenna in the attic and the required coax run. I have read that RG-8 is the coax to use for your feed line, but then I came across RG-213/U coax and it says it is a RG-8 replacement. Is this good stuff to use for the feed line to my 2m/70cm dual band antenna or should I stick with RG-8?
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K5LXP
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« Reply #1 on: May 15, 2003, 06:16:11 PM »

According to the data sheet that I have, 213 has the exact same loss per 100' that RG-8/A does. Yes, you can run 213 anywhere you'd run RG-8. If I'm not mistaken the primary difference between them is the jacket material. At UHF it's kind of lossy though, if you've got a particularily long run I would recommend a higher grade of coax such as LMR 400, LMR 600 or even heliax.

Mark K5LXP
Albuquerque, NM
k5lxp@arrl.net
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KA9ZIM
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« Reply #2 on: May 15, 2003, 06:20:21 PM »

From the Belden cable company's web site I came up with RG-8/U having 2.6 dB loss per 100' at 400 MHz and RG-213/U having 4.1 dB loss per 100' at 400 MHz.  So if both of the cables you are considering are Belden cables then the RG-8/U is a better choice.  If the cables you are considering are by some other manufactures then you will need to obtain info on that particular cable's losses at you maximum operating frequency and make your choice based on loss vs. cost.
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N6AJR
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« Reply #3 on: May 15, 2003, 06:57:11 PM »

You can look up the table at the belden site ( google search) but I try to keep my Vhf and Uhf runs to 20 or 30 feet and use RG8X for them.  

This is lossier than 8 u or 213 but its cheep and I get a 500 foot roll for around $60.  I don't use rg58 ( even worse in losses) except for mobile use.  This is because most rg58 is solid core insulation instead of foam so bending it around stuff and getting too hot in the trunk does not make it wander around in the dialectric. And most mobile runs are in the 10 to 15 foot length so minimal loss no mater what you use.

 But use what you have, and buy the best you can afford, but remember this is a hobby not an obsession.  Pretty good is ok, ya don't need to run hard line fo 440 satilite work.  

73  tom N6AJR
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AC5E
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« Reply #4 on: May 15, 2003, 07:17:28 PM »

Actually, the RG8 confusion is the difference between RG8 Foam and RG8 Solid polyethelene dialectric. The foam has much less loss at VHF and UHF but won't handle as much power, and it's a lot more fragile than the solid poly.

RG8 has not been "MIL-SPEC'd" for many years and a lot of stuff is floating around with an RG8 label that isn't fit for low power jumpers - and a lot that is as good as any coax you can get.

RG213 is MIL SPEC, made to tight military specifications, and that lable should mean you have good, durable, and well shielded coax.

73 Pete Allen AC5E
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AA4PB
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« Reply #5 on: May 15, 2003, 08:14:08 PM »

I believe RG-213 also has a non-contaminating jacket which means longer life. Personally, I'd go for the RG-213 for HF work.

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KA2UUP
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« Reply #6 on: May 16, 2003, 08:40:44 AM »

Try this URL:  http://www.radio-ware.com/

I ordered from them two 75' fabricated sections (professionally soldered UHF connectors) of their 9913 cable.  If you have a rotor, you may want to use the 9914 buryflex.  Both are low loss, about 2.6-2.7 dBs at 400 MHz.  Check the price, it may be a little expensive, but they have worked for me very, very well.

Hope this helps!

Good luck DE Bert @ KA2UUP
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WB2WIK
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« Reply #7 on: May 16, 2003, 12:53:21 PM »

"RG8" has become generic, like Frigidaire or Kleenex.

Real mil-spec RG8A/U is nearly identical to real mil-spec RG213/U, the only difference being the stranding of the center conductor.  They have absolutely identical loss.

When you "look up" stuff on Belden's website (and many others), it's easy to be misled by the data because they call every cable that is .405" diameter and 50 Ohms "RG8," even though the cables vary considerably.  The 2.6~2.7 dB/100' loss stuff is not RG8 at all, it's 9913 or 9913F, etc.  

To add even more confusion, the hobbyist market evolved a .242" diameter very flexible cable called "RG8X" or "RG8M" or "Mini-8," and a lot of people confuse that with RG8/U.  They're very different.

For VHF-UHF use, I'd go with the low-loss stuff which is neither RG8 nor RG213, but 9913, or 9914, or 9086, or 9096-IIA, or LMR400, or CXP-1318, or Davis BuryFlex, or whatever.  These all have much less loss than "RG8" or RG213/U, but have the same outside diameter.  They cost a bit more but can have about half the loss of conventional (military) cables of the same diameter, and since we're hobbyists and not the Marines, it's good enough for most ham use.

WB2WIK/6
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KA2UUP
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« Reply #8 on: May 16, 2003, 04:04:02 PM »

To WB2WIK:

"The 2.6~2.7 dB/100' loss stuff is not RG8 at all, it's 9913 or 9913F, etc."

That is exactly what I said!

73 DE Bert @ KA2UUP
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CRBOWERS
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« Reply #9 on: May 19, 2003, 05:38:53 PM »

Thanks for all the help. I'm on a pretty tight budget and the RG-213/U is pretty cheap around here, if I go to LMR400 it is about 40 cents more expensive, unless I order it. I've been doing some reading and I get mixed responses, some people say I NEED LMR400 for UHF/VHF work. I'm doing a pretty short run of maybe 60' in the attic, will the loss with RG-213/U be really so great that I need LMR400 or will it be fine.
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WA9SVD
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« Reply #10 on: May 22, 2003, 04:40:35 PM »

Will this be an indoor or outdoor installation?  The type of cable and installation can make a difference; some "RG-8 type" cable may be OK for an indoor installation but not be the best choice for exposure to the elements.
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