RG58U Coax. All the same?

Submitted: Thursday, Sep 30, 2004 at 06:52

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rolande

Is all RG58U coax the same? Looking at buying some to put UHF and AM radios into the Patrol. I have some that is about 15 years old but would think it may be too brittle.
Is there any difference between the stuff at Bunnings and the stuff at the local radio shop at double the price.

Any thoughts appreciated

Rolande

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Reply By: bushfix - Thursday, Sep 30, 2004 at 08:22

Thursday, Sep 30, 2004 at 08:22

G'day Rolande,

Practically, apart from price, insulation (signal to noise ratio etc.) and losses should be the only issues I reckon. A quick read along the cable could tell you something. ie. Manufacturer like Belden (probably what your local radio shop supplies) would indicate good quality, low loss. The stuff at Bunnings may be something else or unnamed, in which case you have to 'suck and see.' Have a look end on and you might see a significant difference in the insulation qualities. A solid core conductor would be better than multicore I believe.

If the cables appear the same, go Bunnings. In any case I would suggest you invest in the better quality cable as we are not talking a lot of cost difference but you would want to be happy that your comms install is giving the RF signal the best chance.

cheers,

Jeremy.

AnswerID: 78295

Follow Up By: rolande- Thursday, Sep 30, 2004 at 23:24

Thursday, Sep 30, 2004 at 23:24

Thanks Jeremy, will look out for the Beldon brand
Rolande

FollowupID: 337962

Follow Up By: antenna guru - Saturday, Oct 02, 2004 at 10:42

Saturday, Oct 02, 2004 at 10:42

Rolande,
Essentially you need to look on the cable. If it is printed with MIL SPEC it is made to a specification. All Coax whether it be distributed by Belden, RFI, Huber & Suhner and so on will all be manufactured to the same specification and provide the same electrical characteristics if it is MIL SPEC.

From their you can look at variations of RG58 - RG58 Cellfoam which is made to better electrical specifications, or RG58 Cellfoil, which is again lightly better.

At the 27mhz or 477 mhz frequencies standard RG58 made to mil spec standards will suffice with a 5m run costing you no more than 2db of loses @ 477mhz. Most antennas on the market will come supplied at these frequencies with cell foam cable. This will give you no more thanabout 1.8 db @ 477mhz.

If you are looking ate replacing a cellular cable run then cell foil is the way to go.

Most communication dealers stock RFI cable sold as 8058 for RG58, 9001 for cell foam and 9006 for cell foil.

RFI have a really comprehensive web site and will give you attanuation loses on a wide range of cables at
http://www.rfi.com.au/rfiproducts/cablesConnectors/cable_attenuation_r171.pdf

FollowupID: 338087

Follow Up By: rolande- Tuesday, Oct 05, 2004 at 21:59

Tuesday, Oct 05, 2004 at 21:59

Thanks for the info, will check out the site.
Rolande

FollowupID: 338425

Reply By: MrBitchi - Thursday, Sep 30, 2004 at 13:31

Reply By: ColinD - Thursday, Sep 30, 2004 at 19:20

Thursday, Sep 30, 2004 at 19:20

Agree with the above. You will reap the benefits long term by getting quality. Important to route the cable as far as practicle away from noise transmitters such as ignition and alternator or other AC source. Also apply some form of environmental seal around the connector at the antenna (self almalgamating tape) to reduce loss due to corrosion. Very important that the cable has the recommended impedance, I think usually 75ohms. Lastly give your UHF clean power, get this straight from the battery, negative and positive............ave a goodn....col

AnswerID: 78393

Follow Up By: rolande- Thursday, Sep 30, 2004 at 23:25

Thursday, Sep 30, 2004 at 23:25

Thanks for the advice Col, will do.
Rolande

FollowupID: 337964

Follow Up By: V8troopie - Thursday, Sep 30, 2004 at 23:57

Thursday, Sep 30, 2004 at 23:57

Please note, Coax cable for two way radio to be 50 ohm! only. 75 ohm is for TV aerials.
re the comments about solid centre conductor, I beg to differ from the above advise and say multistrand centre conductor is MUCH better for applications where the cable is subjected to vibrations, like in a car. After all, the wiring in the car is multistrand for the very same reason.

A good quality coaxial cable will have a tightly knit, tinned copper weave screen and a tinned multistrand centre conductor. The insulation between the two will be of good quality and consistentency. The outer plastic insulation will also be good quality plastic, preferably black if the cable is exposed to the sun.

Of course, anybody can instantly ruin the best cable by using crappy connectors or fitting good connectors in a sloppy unworkmanlike fashion.
Klaus

FollowupID: 337972

Follow Up By: bushfix - Friday, Oct 01, 2004 at 07:21

Friday, Oct 01, 2004 at 07:21

G'day V8troopie,

yeah, interesting point re the vibrations. I thought multicore wiring was used to allow more flexible routing through the vehicle i.e many bends and weaves. Will contact GME and bounce it off them. Can you get RG58u in multicore?

cheers,

Jeremy.

FollowupID: 337979

Follow Up By: bushfix - Friday, Oct 01, 2004 at 09:54

Friday, Oct 01, 2004 at 09:54

Yep, guess I threw a spanner in the works mentioning solid core. I used to do broadcast transmission site installs so am used to thinking solid core for best signal. GME concur that multicore is used in vehicles due to flexibility in installation paths. I checked with Belden at

http://www.belden.com.au/beldencatalogue/PDFS_links%20to%20docs/06_Coax/6.9.pdf

looks like Belden 8259 or 8262 are the go, i.e. TC (tinned copper) core as opposed to BC (bare copper core.)

aaaaaaaaaghhhh that's enough techo talk!

FollowupID: 337993