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RG58 cable etc. How do you know?

Posted: Thu Oct 23, 2008 3:25 pm
by cardiffrob
I've got a few sections of coax cale from old aircraft radios. How does one tell if it is RG58 C/U as specified in the installation manual?

Posted: Thu Oct 23, 2008 3:29 pm
by cardiffrob
Thinking about it, does anyone have a lightweight antenna and at least 2 meteres of cable on it? Also, a couple of the TRS headset jack plug sockets?

Valcom 760 radio.

Cheers.

Rob Thomas
South Wales

Posted: Thu Oct 23, 2008 7:34 pm
by PB
It will have RG58 printed on it at intervals....

Posted: Fri Oct 24, 2008 8:30 am
by tnowak
Unless the cable is marked you cannot tell. So many coax cables look near identical but their characteristics are so different.
Tony Nowak

Posted: Fri Oct 31, 2008 6:02 pm
by Rob Swain
Easiest way to know you have RG58 is to buy it new.

Doesn't cost much and the likes of Maplin sell it by the metre.

Posted: Sat Nov 01, 2008 7:57 am
by cardiffrob
My radio manual specified RG58c/u cable but I couldn't find that EXACT reference at Maplins, RS or Farnell. I did, however, have a pile of old cables with connectors already fitted at each end. It would've been great to have saved the effort and used some of the garage clutter. In the end, a fine chap has made me a complete aerial 'kit' for not much more than the postage costs from Maplins! Nice shiny stainless lightweigh aerial wire thingy. No more wiggly amp confusion! Also, the aerial connector at the box end has to be a specific one and he had a pile of ex Navy connectors that fitted the quick-release radio tray.

Posted: Sat Nov 01, 2008 8:18 am
by Ian Melville
The Maplin and RS stuff should be OK, in fact, a better bet than that you find kicking around. However if you really want RG58C/U
http://www.nevadaradio.co.uk/acatalog/c ... 58cu1.html

This one is mil spec

Posted: Sat Nov 01, 2008 6:11 pm
by cardiffrob
Cheers.

A 100 metre (£39:95 plus postage and VAT) roll might come in handy when I have to fit a Mode S transponder a safe distance away! :lol:

Has anyone got an ideas as to what the difference is with RG58 and RG58c/u? Not too worried, now that my new £25-ish aerial kit is in the post, but it would be interesting to see what the 'radio Anorak' meant when he was writing the manual.

Why can't people keep it simple? :roll:

Posted: Sat Nov 01, 2008 7:40 pm
by Ian Melville
For the cable types
http://www.belden.com.au/beldencatalogu ... ax/6.9.pdf
For the abbreviations
http://www.belden.com.au/beldencatalogu ... x/6.15.pdf

If you are looking at RG58 and it has a multicore inner that is tinned, Solid insulator, and a tinned braid outer, then it is very likely that it is RG58C/U

PS Maplin photo is wrong

Posted: Sun Nov 02, 2008 8:45 am
by cardiffrob
Thanks for that, Ian.

Added to my list of handy links since it has a tech advice section.

Hey! Maybe that would be a good thing to add to the website? A 'sticky' list of handy websites with tech info like this that doesn't fit the usual mould?

Just a thought.



PS I'm not volunteering. I can't even program my wristwatch. :cry:

Posted: Sat Nov 08, 2008 9:53 am
by JonKil
cardiffrob wrote: A 100 metre (£39:95 plus postage and VAT) roll might come in handy when I have to fit a Mode S transponder a safe distance away! :lol:
RG 58 or 58U not suitable for mode S. Frequencies too high. Cable for this installation has higher freq characteristics and is not so tolerant of mechanical stress. Check this out before you fit the transponder. Using wrong cable (or wrongly tuned antenna) can cause high SWR in the system resulting in reflected power being sent back through the cable and "blowing" the output amp. A lot of the installations I look at that are having problems can be traced back to poor installation of the antenna and wrong cable being used, the range and performance can be dramatically improved by having this feature properly installed. I have learned this from building antennas for amateur radio use over the years.

And by the way, that is a completely crazy price for RG58/U... 100% too expensive.
Check these guys out for the prices, £18.50 for the same 100 metre reel
http://cpc.farnell.com/CBBR0133/cable-w ... black-100m