Kevlar/wire

Hello,
Does anyone have any experience of Kevlar twined wire?
It has a weight of 1.35kg per 100M. Wire is silver (16/4/0.1mm) with a rating of 2 kilowatt RF.
In these coming winter months I am thinking for something for an antenna next year.
Best price found so far is 90 UK pounds for 100M.
Any comments?
Thanks
Mike

Just found this on e bay
its copper wire interlaced slightly less than £100

http://www.ebay.co.uk/itm/Nevada-Kevlar-32D-heavy-duty-antenna-wire-superb-quality-WEEKLY-DEAL-PRICE-/181591195322?pt=UK_Mobile_Phones_Communication_Radio_Antennas&hash=item2a47adbeba

or this could be useful
http://www.ebay.co.uk/itm/50-MTRS-Of-Poly-Coated-Flex-Weave-Antenna-Aerial-Wire-Ham-Amateur-Radio-Use/221234081153?_trksid=p2047675.c100005.m1851&_trkparms=aid%3D222007%26algo%3DSIC.MBE%26ao%3D1%26asc%3D28111%26meid%3D887b5f85269049b587d3ee99ca354d7d%26pid%3D100005%26prg%3D11472%26rk%3D4%26rkt%3D6%26mehot%3Dag%26sd%3D321397960873&rt=nc

or better still

http://www.ebay.co.uk/itm/ULTRA-STRONG-LIGHTWEIGHT-KEVLAR-ANTENNA-WIRE-100M-IDEAL-FOR-ANTENNA-PROJECTS-NEW-/400779614932?pt=UK_Mobile_Phones_Communication_Radio_Antennas&hash=item5d50539ad4

Thanks Karl,

I am interested in anyone has used/had experience of the the 28D spec.(rather than 32D) with silver.

Thanks for looking it up though.

Evening meal shortly so shut down in awhile.
Night night.
Mike

I use Clansman Dipole wire for a lot of my antennas. It has a kevlar core with copper braid around it (like coax braid) and then a ptfe coating. You can usually find them on Ebay for around 15 or 20 quid incl postage. They come as about 45 metres of wire on a nice winder with a length of thin paracord. Like item 291299257543

Colin

Silver plated copper. But the silver is where it matters, on the surface of the wire where the RF will be found.

My opinion Mike - for HF work a complete waste of money.

73 Phil

Yes but will it really make any appreciable difference?
The Resistivity (ρ) of Copper is 1.678 x 10-8 Ω.m
Silver is1.586 x 10-8 Ω.m, not a lot of difference.

Skin depth at 14Mhz is 17.4242μm and 16.9399μm for silver.

In the same league as audiophiles with their low oxygen speaker leads :stuck_out_tongue:
I’m with Phil on this one, silver plating is a waste of money.
DXwire sell lots of nice copper and tinned copper wire.

(other retailers are also available)

YMMV

Pete :gb:

Well tlhe resistance of a composite conductor where a thin layer of a more conductive metal is electro deposited is quite significantly reduced when the majority of the current is in the skin. So silver on copper is much better than silver. Secondly, corrosion is much less with silver than copper. Corrosion is a surface process and copper only will degrade quicker than silver. Silver suffers from reacting with Hydrogen Sulphide in the air and contact resistance does increase if you don’t solder it. The main commercial reason for silver plated wire is that it maintains conductivity at high temperatures compared to copper and significant ranges of silver plated copper wire can be found using polyamide or fluorocarbon insulation which remain viable upto 200-250C. That wont be a problem in a UK garden environment!

However, I don’t think the silver is the reason to use Kevlar cored wire for an antenna. I think the Kevlar core is the reason to use Kevlar cored wire. It wont snap or stretch and so with the enhanced corrosion resistance you can fit it and to a very large degree forget it.

Hello,

Thanks for comments/help.

“However, I don’t think the silver is the reason to use Kevlar cored wire for an antenna. I think the Kevlar core is the reason to use Kevlar cored wire. It wont snap or stretch and so with the enhanced corrosion resistance you can fit it and to a very large degree forget it.”

Yes these are the reasons I have chosen such wire. I will get some 28D spec. and see how it goes.

I have to make one new antenna and also replace my three quarter wave 40M inverted V next summer. The V has at the end of its ‘legs’ marine cord which then goes through S/S roller wheels to weights. The apex of the V is on a very tall larch tree and despite the movement of the tree the legs remain in position but stretch happens so… I also prefer silver going black to copper going rotten.

Thanks again.
Mike

I was actually thinking along the same lines for a new 60m linked dipole and hoping it would be a bit lighter than the old wire one. Looking for lightness rather than non-stretch as i retune it every time it breaks at the centre. Also possibly replacing the old long-wire and counterpoise and going back to using that with an ATU to be more speedy and flexible with band switching. I suppose the Kevlar is about twice the price of ordinary light-weight antenna wire, so not really an issue when the rest of the gear is a bit more costly :smile:
73,
Rod

Hi Andy,

I think you meant that silver plated copper is better than copper.

Pure silver would be better than silver plating but you need deeper pockets.

I use “DX wire” which is a plated wire with a tough core and outer skin and cost around $1/m. I wouldn’t leave home without it.

73
Ron
VK3AFW

No. Electro deposited Silver on Copper is better than pure Silver. Yes, that doesn’t seem right but apparently is correct.

There are nine different versions of DX wire available from the company DX wire, found on-line, along with other suppliers.

I have just ordered quite a lot of the UL which is Aramid (Kevlar) cored and extremely lightweight so should be good for SOTA. Awaiting a quote for carriage before confirming the order.

I will report back in due course.

73,
Rod

Interesting thread MIke…if the Kevlar wire is as strong as suggested it’s not as expensive as I thought it would be. I haven’t compared the conductor size to the cheap stuff I use. I don’t know what the breaking strain is of the wire I use either. I tend to go for cheap in the garden for the home station for dipoles and inverted Ls.

For years I have used 18 AWG UL1015 105c temp rating multi stranded equipment wire like this from CPC:

WIRE UL1015 18AWG RED 305M
Conductor Area CSA: 0.816mm²
Conductor Material: Copper
Conductor Size AWG: 18AWG
External Diameter: 2.845mm
Jacket Colour: Red
Jacket Material: PVC (Polyvinyl Chloride)
No. of Max Strands x Strand Size: 16 x 0.255mm
Reel Length (Imperial): 1000ft
Reel Length (Metric): 304.8m
SVHC: No SVHC (16-Jun-2014)
Voltage Rating: 600V
Cable UL Style Number: UL1015
Conductor Make-up: 16 / 30AWG
Current Rating: 18A
MSL: -
No. of Cores: 1
Operating Temperature Max: 105°C
Operating Temperature Min: -20°C
Outer Diameter: 2.85mm
Secondary Insulation Colour: Red
Secondary Insulation Material: PVC
Voltage Rating V AC: 600V
Wire Size: 18AWG

£69 for a 305m roll post free

Chinese wire. Some years ago I bought a few lifetimes supply of this grade, the same as now advertised. It’s tough and I don’t remember any ever snapping. It’s rather inflexible for SOTA activations though, fine for home. I was using a much thinner equipment wire until recently, but after two breakages out of 30 activations on my trip to FN this year I have upgraded my portable antennas to the sort of wire used for test leads 55/0.01mm, with the soft insulation. It’s quite thick in terms of insulation but is less prone to tangling. E-bay: enter link description here. That comes out at £10.89 for two 25m rolls red (for centre) black (for screen) so quite expensive. I just use simple phono plugs for my dipole links now, so far they haven’t pulled off when shrink sleeving is used to strengthen the conenctions. I don’t believe in using a balun for a dipole that is being thrown up willy nilly for no more than an hour either. You want as little weight as possible at the top of our spindly fishing poles. Coax - I accept the loss and use the thin stuff in the field (RG-178 or 179) can’t read the cable markings as its worn off!). At home I have gone the other way and when I retired I spent an amount from my lump sum and buried the costly Ecoflex 15 coax I bought underground.

73 Phil G4OBK

Hi Andy,

I can see no reason why it could be so. Frankly I don’t believe it. Perhaps it is the definition of “better” but I can’t imagine wht that might be so let me explain why I disagree.

A quick look at a text book will show you that the rf resistance is inversely proportional to the skin depth and directly proportional to the resistivity of the material. For plated surfaces it depends on the relative thickness of the plating layer, the skin depths and material resistivities. The plating does not create magic.

The skin depth in silver at 10 MHz is 20 um and for copper at 10 MHz it is 21 um. Silver has about 5% less resistivity than copper. So using silver wire instead of copper wire makes little difference to the rf resistance.

Now for the plated copper wire.
If the silver plating is equal to three times the skin depth then very little current (< 5%) will flow in the copper. The rf resistance will be almost the same as silver alone.

If the plating is less than 1/3 the skin depth then a substantial amount of the rf will flow in the copper. The rf resistance will be less than for copper alone but noticeably greater than for all silver. The differences are however all small.

The elephant in the room is that typically the plating is 1 to 2 micrometers thick which is 5 to 10% of the skin depth at 10 MHz. So most of the rf flows in the copper anyway! the rf resistance is almost unchanged!

There is no significant gain in rf performance for good copper wire whether you plate it with silver or not.

So why plate copper? Silver oxide is a much better conductor than copper oxide. So if the conductor cannot be kept with a clean shiny surface, silver plating will give good rf conductivity even when tarnished. Oxidised copper also makes good rectifiers.

Gold is more resistant to tarnishing but the plating process may give the gold plate a resistivity greater than copper. The lack of tarnishing is often worth the slightly higher loss and higher cost…

If you are silver or gold plating steel then you need to have the plating three times the skin depth (60 micrometer at 10 MHz) as steel is not a particularly good conductor and its permeability creates a very small intrinsic skin depth making it horrid at rf. It’s rubbish even at 50 Hz.

73
Ron
VK3AFW
.

1 Like

Ron, you can believe what you want. You can believe the world is flat if it makes you happy.

Hello Phil,

As I said in my opening post £99 for 100M from Nevada with a nice green covering.
I have been using similar wire as you but the Kevlar stuff should last a good time and be better.

I also use Ecoflex along with the superb connectors from SSB Electronics. As part of the ongoing refurb last year I replaced the cable to the inverted V (it had been Westflex) with Ecoflex. The hexbeam has it and the only co-ax cable renewal remaining is to the SteppIR vertical - I did an extremely stupid thing when I ran the co-ax through conduit to the base - I tie clipped the control wire to the cable for about 4 metres so I could pull both through at the same time now of course I cannot withdraw the co-ax without dragging the control line!

I run tests on the co-ax every now and then and keep the record from the AIM4170. Interesting comparing graphs over time even though the information tells me I have to creak open my wallet :wink:
Bye for now.
Mike

Hmmm - I often write comments in various science forums, and if I were to write such a one as this I would be gunned down in flames. The other forum “residents” would ask for references to support my claims. Just sayin’…

And just for the record, the world IS flat - I just went outside to check :smiley:

I just noticed I used the word “just” 3 times… Oh, did I mention I’m enjoying this thread - most illuminating.

R

4 Likes

G’day,

Well we all believe what we want to believe.

For example I believe that assertions that A is better than B need to be backed up with a reasoned argument preferably including real data. Repeating that the earth is flat in increasing strident tones won’t advance anyone’s knowledge. Going outside and looking is a start.

Until I see some proper alternative analysis I’ll stick to the established basic engineering and physics. Oh and also my experience as an electrical, electronic and communications engineer.

Silver plated copper wire is nice but only more effective at rf because even when tarnished it is a good conductor and allows the clean copper underneath to carry 99% + of the current. See my last post.

Salesmen love to promote silver plating in case you hadn’t noticed. Bull**** baffles brains often enough for it to remain a productive activity.

These forums should be about information sharing and rational evaluation of ideas IMO.

If indeed a micron of silver plating on copper is better than pure silver then please show me why.

Until then I will (stubbornly) stick to my belief it isn’t.

73
Ron
VK3AFW

Hi,
Many VK activators are happily using DX Wire UL. Tinned copper wire with Kevlar core, breaking strain 60 kg. Suits us fine. It was bought in from China in km roll.

73
Ron
VK3AFW