Author Topic: Which antenna co-ax?  (Read 2208 times)

ls8pilot

Which antenna co-ax?
« on: February 03, 2021, 01:24:11 pm »
Doing the preparation for our new Atom/Grid instal. Slightly complicated as I cant get site access at the moment to measure cable runs to the antenna location, so wondering about just bulk buying the cable and connectors so we can make it up on site when we get access.  There seems to be a big price difference between RG8, RG8x and LMR400.  I think we're going to end up with about 8m cable run, so just wondered what experience is with the different cable grades  and what people typically use? 

AlanG

Re: Which antenna co-ax?
« Reply #1 on: February 03, 2021, 07:26:24 pm »
Doing the preparation for our new Atom/Grid instal. Slightly complicated as I cant get site access at the moment to measure cable runs to the antenna location, so wondering about just bulk buying the cable and connectors so we can make it up on site when we get access.  There seems to be a big price difference between RG8, RG8x and LMR400.  I think we're going to end up with about 8m cable run, so just wondered what experience is with the different cable grades  and what people typically use? 

Hi
This is the cable I used for my Atom/Grid unit.
  https://www.wifi-antennas.co.uk/cable-crimps-and-crimp-tools/coaxial-cable/hdf400-coaxial-cables
I bought 10 meters and used it for two aprox 4.5m runs on my P3i and Flarm antennas and just used ordinary low loss satellite tv coax on the 1090 antenna.  It's a strong signal so not so critical.
You can get all your connectors from the same source too.

Regards
Alan

exfirepro

Re: Which antenna co-ax?
« Reply #2 on: February 04, 2021, 09:31:31 am »
Hi Julian,

It’s always best to use good quality coax for the P3i and FLARM Antennas in view of the relatively low signal strengths - especially if you are talking about 8-10 metre lengths. As Alan has said, you can get away with a lower quality coax for the 1090 side, where the likes of RG8x or similar will be perfectly adequate and will give good reliability.

Best Regards

Peter

Keithvinning

Re: Which antenna co-ax?
« Reply #3 on: February 08, 2021, 04:44:52 pm »
Hi Julian

RG8 and LM400 are very thick low loss cables
RG8x and CLF 200 are the thinner versions

The thinner versions are OK for up to 4 metres.

I buy in bulk if you want me to make the cables up at cost

Regards

Keith
« Last Edit: February 08, 2021, 06:25:16 pm by Keithvinning »

steveu

Re: Which antenna co-ax?
« Reply #4 on: February 09, 2021, 10:52:11 am »
I'm going to advance a slightly different line of thought to the cable fabrication.

I'm basically a broadcast engineer, and have over a fairly long period had to terminate BNC, various other RF and audio cables.

There's no point spending a lot of time putting up a ground station if it going to be let down by basic details like cable, or cable termination, and allow a certain hostile magazine to write disparaging articles about PilotAware as a whole and ground station maintainers in particular.

In my opinion, in order to do the job properly you will need the right crimp tool for that particular cable and connector, and an average, cheap BNC type crimp tool will not be right for the job, as the crimp dimensions are tied to the inner pin diameter and the same for the outer ferrule.

I measured my cable lengths, costed getting the connectors, cable and the right crimp tool, and then asked Keith for the cost of him helping me out. Keith was cheaper or same plus postage, IIRC.

I put up the aerials, measured the exact cable runs with string, and gave the numbers to Keith.

He did the business.

I had all the cables in the same type, as it would then be possible to swap them around for fault finding.

When I put the station up for the first time, coverage was very good as seen on gliderradar with their basic overage tool.

Possible BS alert - with the better cable on the 1090 antenna, the SDR runs at a lower gain, so lower noise, better results. Keith or Lee will soon have me descending in flames, but why not?

Unless you are sure of doing a good job, get a good job done for you.

Please don't be one of the anonymous ones who gives interviews to Flyer magazine, about how your ground station crashes, how the coverage is poor and how you've not been able to get your finger out and place the aerials outside where they will work, somehow implying that it's someone else's fault.

There are some very good replies from those above with excellent RF skills. If you don't have those skills, then maybe the simpler route is the one for you.

I took the simpler route. It worked for me.