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Author Topic: which Coax 9913 or LMR 600  (Read 1026 times)
KA5ROW
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« on: August 04, 2004, 03:05:55 PM »

CableXperts 1813 or LMR 600
This coax will be 75 Ft and will connect to a remote antenna switch (Ameritron RCS 8V) then to my 2 Meter boomer. Is there enough difference to notice or not on 2 meter ssb.
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AD5X
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« Reply #1 on: August 04, 2004, 03:23:24 PM »

LMR-400 (I wouldn't use 9913) has a loss of 1.1 dB for 75 feet at 145 mhz.  LMR-600 has a loss of 0.7 dB.  A difference of 0.4 dB won' be heard.  This would only be important if you were into moon-bounce!  Also, you can use standard RG8-size type N or PL-259 connectors on LMR-400.

See http://www.ocarc.ca/coax.htm.

73,
Phil - AD5X
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AA4PB
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« Reply #2 on: August 04, 2004, 03:37:35 PM »

Do you mean CableXpers 1318 (same as RG8 or RG9913)?

My calculator shows 9913 at a matched loss of 1.565 dB per 100 Ft.  LMR600 is 0.998 dB per 100 Ft. You are probably talking about a 0.5 dB difference for your run. Not very significant unless you are trying to do some really weak signal work.
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WB2WIK
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« Reply #3 on: August 04, 2004, 04:53:32 PM »

These cables aren't very comparable, except that they're both 50 Ohm coax.

LMR600 is a specialty cable requiring specialty connectors.  Besides being larger and lower loss than 9913 types (including CXP1318FX), LMR600 is *very* inflexible and requires a large bend radius -- quite a bit larger than the .405" diameter cables.  But it's also "tougher."  LMR600 is mechanically stronger than 9913, CXB1318FX or LMR400 and will withstand a great deal more abuse, including tightly taping or clamping to tower legs or antenna booms, stuff like that.

LMR600 can also handle a *lot* of power.  Far more than the amateur legal limit, so this isn't too great a feature for most hams, but it's a consideration for some who might want to run legal-limit power on 70cm, for example.  (9913/CXP/LMR400 actually gets quite warm doing this -- LMR600 won't.)

Of course, if you're going with the Ameritron remote switch, then possibly the absolutely lowest loss isn't your prime consideration -- because the RCS8V has some loss at two meters, already.  At least the two I've owned certainly did -- I could measure it on the bench using a signal generator and microwattmeter.  I think the last one I had measured about half a dB at 144 MHz, depending upon which port was selected.  This isn't much loss, but it's some, and about the difference in loss between LMR400 and LMR600 at that frequency.

LMR600 is, if you haven't "felt" it, quite inflexible.  Definitely can't go around a rotator, and probably not up the side of a telescoping tower, either.  But for straight runs where the large bend radius isn't a problem, it's very good stuff.

WB2WIK/6

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VK4KX
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« Reply #4 on: August 04, 2004, 10:11:34 PM »

Have you thought about remote mounting the radio on the tower and just having the radio head in the shack.
That way all the power will enter the antenna.
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KB0ETC
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« Reply #5 on: August 05, 2004, 01:01:41 PM »

Is the antenna rotatable?  You will have to be extremely careful about the rotator loop if any.  LMR has UltraFlex that is okay for rotor loops, but the solid stuff will eventually fail from the stress.

I run heliax to the tower using a remote antenna swtich, then 213 to the antennas.  Not enough 213 coax to have a lot of loss.
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N8EKT
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« Reply #6 on: August 05, 2004, 04:05:57 PM »

DON'T WAIST YOUR MONEY ON LMR CABLE
LMR CABLE IS VERY STIFF, AND CONNECTORS VERY EXPENSIVE
YOU NEED A FLEXIBLE CABLE FOR DIRECTIONAL ANTENNAS
AND AT 2METERS AND ONLY 75 FOOT, YOU WILL GAIN NOTHING
BUT A LIGHTER WALLET
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K4III
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« Reply #7 on: August 05, 2004, 10:11:56 PM »

9913 is very prone to water infiltration if I remember correctly... May want to ask around. I know of very few outdoor installations where this coax was internally dry! (Maybe I'm getting confused though with 9914.) One of these holds and attracts water like a hose!
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K4III
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« Reply #8 on: August 05, 2004, 10:18:27 PM »

Also,

LMR may cost more, but it will last decades as opposed to a few years. My opinion is you spend just as much sometimes purchasing cheap and replacing and repairing than spending the dough correctly at the beginning saving valuable time, effort and end up with a professional installation and product. (Especially when climbing towers and installing equipment you don't necessarily want to mess with on a regular basis)

I've seen LMR cable still in decent condition left to the elements for over a decade in a saltwater environment less than 500 feet from the beach atop condos! Well, ok, the outside connectors are sometimes a little corroded, usually from being left hanging abandoned, but that is usually it!

Also you may want to see whether any old 75 ohm tv coax is available. With a tuned antenna 1:1, the difference in impedence will usually show only a 1.5:1 and sometimes even better and usually runs under 300 feet are given away or scrapped! (In case you're "strapped" wallet-wise for good cable)
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W5WJP
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Posts: 157




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« Reply #9 on: August 06, 2004, 02:54:06 AM »

I use Cablexperts CPX1318FX for almost all my coax. Very flexible and has losses similiar to LMR400. No problems with water infiltration, but I do cheat a bit, I buy premade runs with the connectors on them. Doesn't cost too much more and with age and arthritis, it helps a lot. Cablexperts does a fine job with the connectors and they use heat shrink to seal the back end of the connector. By the time I get done sealing the joint, there is enough tape over everything to keep water out for many many moons.

73,
W5WJP
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WA4DOU
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Posts: 436




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« Reply #10 on: August 06, 2004, 03:48:16 PM »

You can often buy Andrew LDF4-50 1/2" hardline, new from individuals for $1.00 per foot, or even slightly less. At $10-$15 each for good used connectors and .8db of loss per 100 ft. at 150 mhz., I'd strongly consider that route over both LMR400 and LMR600. If you're well connected to other hams in the land mobile radio business you can sometimes get 1/2" and 7/8" heliax for free.
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