LMR-400 Longevity

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N4IFE

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In 2007 (15 years ago) I ordered 100 feet of Times Microwave Systems LMR400 Coax. It has since sat, unused and still in the shipped coil, in my garage. The garage is protected but still subject to south Florida heat and humidity. I want to use this cable now for a VHF/UHF dual band antenna in my attic but would first like to get an idea if I could expect to have degraded over those 15 years.
 

N5XPM

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In 2007 (15 years ago) I ordered 100 feet of Times Microwave Systems LMR400 Coax. It has since sat, unused and still in the shipped coil, in my garage. The garage is protected but still subject to south Florida heat and humidity. I want to use this cable now for a VHF/UHF dual band antenna in my attic but would first like to get an idea if I could expect to have degraded over those 15 years.
Does the cable have connectors and vapor block installed?
 
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mmckenna

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Should be OK. You'll probably want to cut off a few inches from the exposed end. Strip back the cable and expose the center conductor. If it's clean and shiny, you are OK.
Risk is that moisture will creep up the cable and corrode things.
 

RFI-EMI-GUY

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I have a roll of 9913 in exact same condition. I do try to maintain <55% RH but it fluctuates.
 

K6GBW

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I recent ran a 100 foot length of Time Microwave LMR400 that sat in a garage since the early 90's. It works perfectly fine. I've used cables that have been on roofs in the sun for twenty years and as long as they aren't compromised in so way they're good too. Just keep water out and don't let rodents eat the stuff and you should be good to go.
 

merlin

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I have 200' = LMR600ds. 65' installed 3 years ago. All is still like new.
Shelf life, probably 100 years.
I did something new for weather sealing outdoors. After a good packing of #4 compound in connectors, I wrapped with ordinary electrical tape.
Then a good coating of 'Flex-Seal' The last check with a TDR, the integrity is 100%. the seal still water tight.
The rodent and open ends points above should be considered.
Your coax should be just fine.
73s
 

mkewman

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The real concerns are UV, Water and Rodents. If it's sat in relatively dry place without direct sunlight, you're probably fine. I'm in the midst of replacing some 20+ year runs on a roof that are now completely roached by the sun.
 

AZDon

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Not the same as LMR 400 but you better believe a lot of 1/2”, 7/8” and 1 5/8” heliax is hanging on towers all over the country for decades. Sure UV, heat, temperature and light will have advers impact on LMR 400 but it will last for years especially if it’s still in its original condition. unless you have water getting into the 400 or there is no physical damage or kinks it’s fine.
 

dogtowndrums

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Just use it. I've had a run of the same Times Microwave LMR 400 out in the elements here in the mid-south since 2015. I moved to a new QTH a year ago and swept it on a NanoVNA before I reused it. It specs the same as when I bought it. It is fairly tough stuff. As with any coax, make sure you do a good job of sealing any connections exposed to the elements, don't bend it too acutely during the install, try not to compromise the jacket, and you should be good to go. Silicone tape worked well for me. I'm sure there's somebody around that will disagree on some theoretical basis, but just getting out in the yard and trying it out will be more productive than anything else.
 

prcguy

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UV will degrade things over time but I would not worry about water. I've pulled thousands of feet of LMR400, 500 and 600 through underground conduit that is filled with water 24/7. Those cables will probably out live us all.


The real concerns are UV, Water and Rodents. If it's sat in relatively dry place without direct sunlight, you're probably fine. I'm in the midst of replacing some 20+ year runs on a roof that are now completely roached by the sun.
 

W5lz

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In 2007 (15 years ago) I ordered 100 feet of Times Microwave Systems LMR400 Coax. It has since sat, unused and still in the shipped coil, in my garage. The garage is protected but still subject to south Florida heat and humidity. I want to use this cable now for a VHF/UHF dual band antenna in my attic but would first like to get an idea if I could expect to have degraded over those 15 years.
I seiously doubt that you will be able to tell a difference between that cable and new cable. I'd take the precautions described here and mnot waste any good worry on it
 

mkewman

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I wonder how much life you can expect out of LMR400 in constant sun?

Once you reach the 15-20 year mark, you start seeing issues if it's in direct sunlight, depending on where you are. Out here in California, I replace anything that's 20 years old if it's not already toasty if it's on a roof, especially if it's a rough asphalt.
It kinda depends on how it's installed. Hot Shingle roof? It probably won't last last 20 years in the Sacramento Valley Sun. But if it's mounted on TPO, might last longer. it sorta depends.

If you can get it in shade for part of the day, you might extend its life a few years.
 
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