Anyone have an experience with LMR 400 coax? Is it worth the high cost?
I just bought a length of it for my Midland MXT 400. Anyone care to share their thoughts on it?
It depends on how long you need to run the cable. On short runs of 20 feet or less, RG58 should work just fine and is considerably less expensive. LMR400 is better suited for longer runs because there is less signal loss, however, it is also a lot thicker and is not as flexible, making it impractical for vehicle installations and other short range applications.
Thanks Rick. I’m planning on using LMR400 in my base station so size and lack of flexibility will not be an issue. I’m hoping for a noticeable improvement on receiving weak signals.
If I have the money, and don’t need to bend the cable sharply as you might with a mobile install, I think the better cabling is almost always worth the cost to avoid as much loss as possible. If you’re using a lower wattage radio, which many GMRS mobile radios are, every bit of loss is important (to me).
Thanks Rick for your comments. Update: I received the LMR coax, (around 25-30’). I haven’t had a lot of time to observe any improvement, but during the short time available, I have noticed significant improvement on the receive side! Very happy to confirm what I had expected would happen👍
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LMR400 is a fairly multi-purpose coax. Very handy for base station application especially when talking about VHF/UHF application for 150 ft or less runs. Wouldn’t put it into repeater service (I can go on about why and how it was actually one of the key reasons I left a former employer) but that’s honestly a story that isn’t really important for the purposes of this discussion.
All that being said, when you are pushing power (more than 10W) you really won’t notice a difference when switching to LMR400 over say, RG58. Where it really becomes noticeable is when dealing with receiving weak signals.
Zap, That was actually the reason I wanted to make the change to LMR 400. I was anticipating an improvement on the receive side but boy, was I amazed. I can now talk to people that I didn’t know existed. With the MXT-400, I have more than enough xmit power👍
It’s only about a 25’ run at my base station.
You’ve got me intrigued now? I do have one repeater here that I swapped out the cable for LMR400, and there was a little extra gain over 213 it previously was using. It’s a UHF repeater, not that long feeder runs and no other equipment on site. I’m guessing you’re talking about interference products annoying to other users, but that’s a guess? P
Glad to see some interest in this topic!
The main drawback is of course the dissimilar metals, specifically the silver clad copper braid which sits directly on the aluminum foil secondary shield. Over time the coax tends to absorb moisture regardless of how weather proofed it is. After a few years you’ll often begin to see an increase in noise in a full duplex environment (which you will typically only notice and be able to fully diagnose on analog systems) due to corrosion between the shield materials. Half duplex operation…it will never be an issue though.
Historically I would typically see it develop after 5 years or so. It’s one of those great debates between service, sales and billing. If I use a coax for an on-prem repeater that I know will need to be replaced in 5 years, I can bill a truck roll, labor and material costs. Since it’s been 5 years I can also try and sell a new repeater or entirely new system. Or if I’m one servicing it, I can use a feedline that costs maybe two times as much but the labor is the same and it will be good for the next 15-20 years barring something physically happening to the hardline (like a roofing crew cutting it because it was in the way, don’t laugh I actually had a customer bill their roofing crew for the cut and the repeater who’s PA got fried in the process).
I actually hadn’t noticed the screen covering - I can see why that gives repeater site folk the jitters.