Cables from DX Engineering

[gcopter1]

I'm looking to buy a new cable for my scanner/antenna set up. I've always read that, for 800 MHz applications, an LMR400, is the best cable to use because of its low loss at those frequencies range.

So I used their cable builder tool on the website.

I entered the specs to build me a 75' long cable with PL259 at both ends.

For an LMR400, the quoted price is $97.99.
For an RG-8U, the quoted price is $103.99.

But, the LMR400 specs, show it as the best performer, in terms of lower db loss, for the frequencies I'm mainly interested in using.

There's roughly a $6.00 difference between the two. But, if I'm looking solely at performance, the LMR400 wins.


However, I like the light weight and flexibility of the RG-8U, but not too crazy about the performance.

So my question is, am I paying more on the RG-8U for the lightness and flexibility and performance be damned?

 

[Ryangn]

If you want the flexibility and LMR400 there is the LMR400 Ultraflex - that's what I use. It is a whole lot easier to work with than regular LMR400 but of course more expensive.

 

[jcop225]

You are paying for the additional copper and stranded center conductor in the RG-8.

You are correct that LMR-400 style cables are better in terms of loss and weight, the flexibility of RG-8 means it can last longer in scenarios where it is repeatedly coiled/uncoiled, flexed, vibrated compared to LMR-400. (This is due to the stranded copper center conductor vs. solid copper clad aluminum)

Additionally, do not use PL-259 connectors on an assembly that will be used at 800 MHz, those connectors were only designed to operate up to 300MHz. Match the connector on the cable to the connector on the antenna you plan to use so you do not need any adapters. On the radio side I'd suggest terminating the LMR-400 with a BNC female then you can run a short LMR-195 jumper to your radio.

 

[gcopter1]

Can't find anyone who can build an LMR400 cable assembly, with anything other than PL259 or any other connector like BNC or SMA. The cable thickness itself, does not lend to anything small.

Sent from my SM-N960U using Tapatalk

 

[mmckenna]

Can't find anyone who can build an LMR400 cable assembly, with anything other than PL259 or any other connector like BNC or SMA. The cable thickness itself, does not lend to anything small.

The Antenna Farm will make custom cables.
There are lots of options for connectors that will fit directly on LMR-400. I use N connectors at work on LMR-400 and LMR-600.
UHF/PL-259 connectors will work, but they are less than ideal at higher frequencies.
Antenna Farm will offer heat shrink tubing over the connections. This is a good investment as it helps with strain relief.

As JCOP said, get one end to match your antenna fitting. Make sure you —properly— weatherproof the connection.
On the radio end, terminate the cable with N, BNC, TNC, etc, a suitable high frequency connector. Use a smaller coax to make the final connection to your radio. The LMR-400 is pretty stiff and will put a lot of strain on the antenna connection of your radio if you try to attach it directly. Use a short jumper for RG-58, LMR-200, or a similar size cable to jumper from the LMR-400 to the back of your radio.

 

[mmckenna]

https://www.theantennafarm.com/catalog/times-microwave-lmr-400-1471

 

[jcop225]

I'm not sure of other companies who will do 1-off custom assemblies, as I build most of my cables myself, but I do know that both BNC and SMA connectors are available for LMR-400 but as mmckenna stated they're not usually connected directly to equipment without some sort of mechanical relief.

 

[Radioman77]

Try the RF connection they make custom 1 offs. I get all my cables there.
Home | RF Connection

John W3JJL

 

[SurgePGH]

Can't find anyone who can build an LMR400 cable assembly, with anything other than PL259 or any other connector like BNC or SMA. The cable thickness itself, does not lend to anything small.

Sent from my SM-N960U using Tapatalk

All of the difference between the LMR400 and the RG8 will be lost when you start adding adapters. Radioman77 and mmkenna have the right ideas. Find someone to make it with the exact connectors you need or you're just wasting money. Also keep lightning suppression in mind.

 

[byndhlptom]

If you have a local Ham store/shop, they often will make up cables for you (Mine does). They usually stock most common connectors and coax

$.02

 

[gcopter1]

So, LMR400 it is.
Thanks!

 

[Ubbe]

Just to let you know that 75ft LMR400 attenuates 3dB @900mhz and tripple shielded RG6 4,5dB and costs $16 for a 75ft roll with F connectors attached. The money saved could be used on an antenna mounted low-noise amplifier that gives you no coax loss and improved signal noise ratio in your receiver, if you attenuate the signal at your receiver to give a total gain of max 3dB-6dB. It will equal to more than doubling your current antenna size.

/Ubbe

 

[gcopter1]

I do plan to listen to the aviation band as well, so, not sure if the RG6 vs the LMR400 will make a difference.
The systems I monitor, one has a site just over a mile west of me.
The next system, is a neighboring county, about as far as the first system's tower.
With the stock antenna on the SDS100, I'm getting great results.
I do plan to add an SDS200 to the shack and see what else I can catch with a Diamond D130J in the attic thus my wanting to get the best coax possible.

Thanks for your input, Ubbe, much appreciated.

 

[Ubbe]

thus my wanting to get the best coax possible.

That's everyones wish. But if you only gonna receive then instead look for best possible complete solution. I can put a low-noise amplifier together with a variable attenuator directly to any scanner I have and it will improve reception. I only have short coaxes to antennas and all systems here use 470Mhz or lower so I have no need to put the amplifier at the antenna. But with 75ft and 800Mhz it would make a scanners sensitivity more than double with an antenna mounted amplifier.

/Ubbe

 

[charlieprimero]

Can't find anyone who can build an LMR400 cable assembly

These guys will build any cable, with any connectors you want...

USA Coax - Custom RF coaxial cables by MPD Digital

I spoke to them on the phone. Nice people. Don't mind giving advice. American company. Veteran-owned.

Good interview with the business owner regarding coax here...