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Old 15th May 2022, 4:16 pm   #1
onlineguy
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Default Kevlar antenna wire.

Hello, I'm on with building an antenna for 160,80,40 metres and in need of the afore mentioned Kevlar based antenna wire. Anyone know of a seller in UK or have a roll or two to sell? I see a few emporiums selling similar but it ain't Kevlar!

All best. Andrew.
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Old 15th May 2022, 6:02 pm   #2
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Default Re: Kevlar antenna wire.

How much do you need? A "roll" isn't very informative.
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Old 15th May 2022, 10:43 pm   #3
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Default Re: Kevlar antenna wire.

https://rfcomms.co.uk/

2 quid a meter.

Last edited by Station X; 17th May 2022 at 6:42 am. Reason: Link added.
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Old 15th May 2022, 11:56 pm   #4
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Default Re: Kevlar antenna wire.

Bigfatha

Thanks for that will check it out . All best om.
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Old 16th May 2022, 12:12 am   #5
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Default Re: Kevlar antenna wire.

Graham,

I mention 160 metres..80m and 40m .. anyone with Kevlar based antenna wire would know a bit about whats requred for afore mentioned bands i imagined. Or maybe not if they just sell the stuff..So thanks for the nod.

100 metres for starters would be favourite although any long runs of Kevlar is always handy if you like rolling your own... (Home Brew)
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Old 16th May 2022, 9:26 am   #6
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Default Re: Kevlar antenna wire.

I asked the question because I had no idea what type of antenna you were planning to erect. Presumably it's multi-band? If your plot is large enough for a 160 metre dipole you're very lucky, I've just got room for an 80 metre one.

Another reason I asked the question is because I have a lot of this wire NOS and surplus to requirements.
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Old 16th May 2022, 11:57 am   #7
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Default Re: Kevlar antenna wire.

160, 80 and 40m

There are many ways of making such a set of antennae. A halfwave dipole for each would be roughly 80+40+20 = 140 metres total of element wire. Trapped dipoles would save some wire. Then there are feeders.

I use an 80m band dipole with open wire feeder and a balanced ATU. This tunes up on 40m just nicely and does several other bands. For 160m I join the feeders and tune it up against ground. It works. There are better solutions if I had more space, there are worse solutions. A set of rhombics for each band and several directions would be nice...

I'm curious about why you want Kevlar wire. Kevlar isn't much of a conductor, so it acts as a very high tensile support for a thinner copper wire. Thin means higher resistance which means more loss. For a long end-supported run, copper plated steel would make a more efficient antenna. Kevlar would win on weight and coil-ability for portable use.

Sorry, but you haven't given enough information for even a rough guess of how much you want.

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Old 16th May 2022, 8:28 pm   #8
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Default Re: Kevlar antenna wire.

I've got these unopened "kits" which I believe use Kevlar cored wire. A bit of googling should show how much wire there is in each pack.
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Old 16th May 2022, 9:27 pm   #9
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Default Re: Kevlar antenna wire.

Good Evening Graham
I would very much like 2 of these antenna elements to replace a set that I used for a Scouts JOTA event and when taken down had suffered an attack by tree rats.
Will pm you.
Regards
Mike
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Old 16th May 2022, 9:50 pm   #10
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Default Re: Kevlar antenna wire.

David,

After having problems with a doublet , each leg about 66 feet , believe its copperweld or similar ..very thick and unruly and hard to stretch out in a straight line it always looks full of twists and a mess, im not bothered but l8ke to keep things neat for the missus ! so thought of Kevlar based wire as I have a few Kevelar based wire antennas for the higher bands ..fairly short ..40 metre band and a Windom ..also delta loops etc ..not much wire in them ..I mentioned 100 metres would be ok and give me scope for future projects .

Im interested in your take on the merits of using other conductors as regards various other copper based wire etc..and the resistance values re Kevlar.

Will go have a read up.

After using Kevlar for this n' that over the years I find it easy and light and the green colour of the mil spec stuff has its merits and asthetically ok on the eye .

Thanks for your valuable, as always input.. always an education ! 73.
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Old 16th May 2022, 10:03 pm   #11
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Default Re: Kevlar antenna wire.

Hi Graham , aye , thanks for your take on it all ..Im thinking of 2 projects. A trapped dipole/doublet fed with 450ohm via a balanced tuner. My system at moment is 132 feet top doublet fed with 450ohm all im doing is going to change the unruly wire full of kinks etc to Kevelar based wire.

100 meters would also give me an option on another project I have in mind.

150 feet would do me to replace the one im taking down ..actually 66 feet a side replaces what I have up at moment.

Its inverted V almost with a couple of dog legs ..

Also have in mind a horizontal trapped dipole for 80.40. ..then thinking of experimenting with the G7FEC
..

what length is the Kevlar in each pack ?

Thanks Graham.
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Old 16th May 2022, 10:07 pm   #12
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Default Re: Kevlar antenna wire.

I got 100m of "Flexweave" from an online supplier, theres plenty of reputable ones out there.
I havent used it yet but it's quite nice to handle and unobtrusive going by the 67 foot of end fed I was given by a local amateur.
I was meaning to replace the elements on my G5RV based doublet and the 80m "dipole" thats out of necessity configured as a horizontal V, and both aerials are still using the very ordinary 16x0.2mm PVC insulated wire that I lashed up my initial setup. I took a bit of stretch out and as they aint broke I'm not fixing them just yet.
Anyway the point is flexweave seems cheap and plentiful and I'd be happy using it when I eventually re rig my aerials.
Andy 2E0AND
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Old 16th May 2022, 10:12 pm   #13
onlineguy
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Default Re: Kevlar antenna wire.

David , Graham,

I cant get a full top band antenna in horizontally so I alternate between an inverted "L and my gamma matched tower.

Obviously with the vertical side of the inverted L its always going to be a bit noisey over my past horizontaly polarised systems ..I can switch to the tower for top band and its putting out a decent signal with good inter G coverage. Still all experimental and ongoing.
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Old 16th May 2022, 11:22 pm   #14
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Default Re: Kevlar antenna wire.

Once your antenna is up and tweaked, then your ideal material is copper, at least to the skin depth on the bands in use (assuming silver is right out on budget grounds)

Copper isn't very strong, though it is strong enough given care. The standard recommendation is hard drawn copper. Soft (annealed) copper is easier to form for wiring, but stretches, but it only stretches so far before it work-hardens (IE becomes hard drawn) I have some hard copper but it's a pain when not up. What I've used for years is PVC insulated single core 2.5mm squared multi stranded. The house is on PME so the radio gear inside could, theoretically go live and take the antennae with it, so insulated antenna wire covers that base. It stretches, so I let it get on with it and I can prune as needed. But I'm not using my inverted V doublet at a resonance directly, so my ATU alonf with two pulleys and weights handle the stretch.

The Kevlar-assisted wire fixes a lot of stability issues, but adds loss issues. No such thing as a free lunch, or in this case an expensive lunch.

I have kevlar guy lines for some portable verticals I use. Brilliant stuff, but so much tension on such thin line needs care but those lines (no copper) were a hundred quid some time ago. Hiking up a mountain, they seemed cheap.

There isn't any one all-round good solution, just different compromises.

I think the best advice is to do your experimenting with cheap wire. get your results logged before it stretches too much, or do a little pruning. Only once you've got your ideas stabilised do you break out the expensive stuff. Easy to cut, very difficult to uncut so best do your cutting on the cheap stuff.

David
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Old 17th May 2022, 12:34 am   #15
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Default Re: Kevlar antenna wire.

I may be off topic a little, BUT:
In Australia aerial telephone single pair was made out of very hard drawn copper with a super tough PVC outer. It also had a support wire of high tensile steel, also PVC covered. I used it as a kid for receiving antennae. I have never bothered with transmitting ( legally anyway ).

It used be very cheap.
Its just my idea to see if such was available in UK. Its fat lady style, that is 3 wires in figure 8 plus one .

Joe
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Old 17th May 2022, 12:37 am   #16
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Default Re: Kevlar antenna wire.

I should have added, the copper was very thick for telephone wire. Perhaps 16G.

j.b.
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Old 17th May 2022, 1:39 am   #17
onlineguy
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Default Re: Kevlar antenna wire.

David

Thanks for good input.

I used to use enamelled copper wire and go stretch it and anneal it on local farm gate.. that was ok for my building the 2 element 10 metre quad beams I used to knock up for myself and local operators..had issues with it snapping when employed for 80m band length..kinking now and then..I suppose I could run with what im using but thinner guage if I can find any..this stuff iv got up was for marine use and brand new when i obtained it..too heavy ! Anyway all good fun . 73 David , Graham, et al ..Andrew.
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Old 17th May 2022, 7:50 am   #18
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Default Re: Kevlar antenna wire.

I have had perfect results by using the 2.5 m/m stranded wire which is commonly available and used for house/counduit mains wiring. Never had problems with it here on Anglesey (one of the windiest places in the UK!).
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Old 17th May 2022, 8:23 am   #19
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Default Re: Kevlar antenna wire.

Kevlar as a strength member in cables is surprisingly poor. This is because it has to be sized to not stretch beyond the elastic limit of the copper (4% I think) at max load, otherwise you have a tangled mess when tension releases. In turn this means oversized Kevlar with respect to breaking strength. Combined towing/electrical cables are very carefully configured as a result.
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Old 17th May 2022, 11:24 pm   #20
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Default Re: Kevlar antenna wire.

VT fuse

Mike, I started the thread on Kevlar in asking for some .. Graham replies to me telling me he has got some and you jump in saying you will have it ! And will pm him private !

As It was a thread and a request from me for Kevlar Im wondering why you jumped in on my thread saying you will have what I was offered.. I was brought up with good manners so perhaps its me expecting too much these days ?

Andrew.
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