co axial cable types what is rg58U?

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tim_ber

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I've been told that it is best to run a new wire up my mast.

I can see rg58A/U (very cheap and nasty)
rg58 c/u nicer, bit more expensive,

but what is rg58U (middle priced)??

I may go rg213, but am still keen to know what rg58u is.
 
Ive been thru this as well, rg58 is fine the u bit is a bit more foil, less loss. The posher stuff is thicker and that is the prob, the purists argue to use it but most boats come with 5mm rg58 variants and if you try to fit the posher stuff it physically is a lot more difficult, for what its worth ive just ordered 20mtrs of rg58/u for 7.99 which i am more than happy to use!
Stu
 
The reason for the different types is that smaller (cheaper) coax has a large loss at VHF.
One catalogue (old) I have says RG 58c/U has 16db at 100mhz and 24db at 200 mhz. of attenuation in 100 metres of cable.
RG213/U has 7.2 db of attenuation at 100 mhz and 15.4 at 500 mhz in 100 metres.

Now db is a ration of power 20 log P1/P2 I can't get my head around the math but if I remember rightly at 160mhz and a typical mast height/ cable run of 15 metres you can lose nearly half of your 25 watts before it gets to the antenna with RG 58. While the better coax might lose only 20%.

However again this doesn't matter as much as you might imagine because perceived radio signal strength is also logrythmic so the loss is barely perceived.
So you decide yourself. I think if I had a mast head antenna I would go for the better (lower loss) coax. olewill
 
RG58U is 5mm nominal diameter and has 5dB attenuation (power loss) per 100 feet at 100MHz.
RG8X is 6mm nominal diameter and has 3.4dB attenuation at 100MHz.
RG8U is 10mm diameter and has 2.0 dB attenuation at 100MHz.
RG213 is the same diameter and specification as RG8 but tougher outer coating and is more difficult to make connections.
The U stands for Universal Specification, but I've never seen this defined. The RG, by the way, stands for Registered Government specification.
A loss in the antenna system of 3dB halves the power output.
All the above are 50 ohm output impedence - you can't use 75 ohm (tv, video) cable.
 
Oh, and the most significant measure of quality (assuming the cable is stranded conductor, pvc jacket) is the braid coverage, expressed as a percentage. This should be in the 90's, not the 80's. 92% is ok, 96% is excellent.
 
Will et al
for what its worth I stand by what I said. Was talking to a forumite the other day and he agreed with me, loads of valuable advice here BUT some of the posters are so tied up with theory that peeps can get confused. OK everybody. go to your local swindlery, check out the antennas there with included cable, what is it? RG58 by the looks of it. The wire on my antenna is the original, I know this cause it has the crimped "bullet" connector on it, what is it? RG58! I am replacing it with rg58U because it is supposed to be slightly better BUT more because it is the same diam as the old stuff 5MM, making it easier to pull throught the grommetts etc on the mast.
Now if RG58 is so bad why do Vtronix supply it with their Hawk antennas?

Stu
 
For transmitting I would think it unlikely that there is a discernable difference. Corrosion is the enemy, though. Tinned copper braid is best for marine applications, aluminium foil is the worst.
I have no personal experience of foil, but the 'experts' such as Charlie Wing say 'coaxial cable for marine use should have a tinned center conductor and braid'. Calder also recommends tinned braid and centre core. Everyone agrees the core should be stranded to minimise the chance of breakage.
 
John
just got back to my shop, the cable has arrived, my mistake, it is rg58a/u. Have stripped an inch and to my delight have found it to be tinned braid and tinned centre multi strand core with an alu coat under the braid. For £7.99 for 20 metres I will take a chance on it lasting a few years!
Rocket Radio in Letchworth, no connection
Stu
 
Will
further to my post, arrived today a vtronix bullet to fit on the new rg58au cable, it fits just, the instructions are very specific about it being very tight to screw on the cable, it wouldnt fit on the fatter 7mm posh cable, that ties in with the fact thtat the original is basic rg58 with non tinned braid 5mm
Stu
PS, have just read the instructions and it again is quite specific, RG58 cable.
 
Everyone agrees the core should be stranded to minimise the chance of breakage.
**************************************************

And what is more important....to assist the pin in the bullet connector to penetrate the weave so as to make good connection. Can be a bit hit and miss with single strand centre core.
 
They do, as do some other suppliers, and they have clearly taken the decision that RG58 is OK for a 20m run.
Be aware, however, that others disagree. For instance the offshore racing authorities give this advice:

ii it shall have a masthead antenna, and co-axial feeder cable with not more than 40% power loss

iii the following types and lengths of co-axial feeder cable will meet the requirements of OSR 3.29.1 (b)(ii): (a) up to 15m (50ft) - type RG8X ("mini 8"); (b) 15-28m (50-90ft) - type RG8U; (c) 28-43m (90-140ft) - type 9913F.

So, if you intend to race offshore you shouldn't have RG58 cable.
 
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