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String insulators in link dipoles?

following on from my first wire dipole here

it seems to me that the same approach could be used between sections of a link dipole.
Any reason why not?
then it can we wound up nice and tidy, no drilling, no plastic to fracture etc.

Edit: By string I mean nylon cord like light pulls in bathrooms.

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Try it. Make an antenna. See if it works. See if it works when it’s very wet. See if it stays together when the wind is howling. See if takes the physical strain. See if you can rig it with gloves when it’s very cold.

If it does all of those without constant need of repair you have a solution. If not change the failing part and try again. Lather, rinse, repeat.

A tip when making one of these is try and keep the weight down on the antenna as a whole.

One of the mistakes I made was to make a really good link dipole only to find it was too much for the pole to handle in Winter conditions. Simplicity is key.

Jonathan.

Thanks both.

Jonathan, I was thinking the string would be lighter than anything else could be which should help.

What was the recommended minimum wavelength fraction to keep the ends of an inverted vee from the ground? Was it 1/20th? Of longest wavelength I presume.

Keep the ends at least 1m above ground. Or the height of your walking poles.

Hi Andy,
From the other thread I think Steve is talking about using nylon cord rather than string. I agree with you that if he was using string and it got wet, it could be a problem. The Nylon cord would be the strain relief for the links. There would still of course need to be some kind of connectors for the links themselves (my favourite are 2mm RC power connectors, they have a nice “click” while being small and lightweight).

The feed point could also use nylon cord I exepect however the use of a piece of connector block shown in the other thread, looks like a great idea. The feed point would need some way to be fastened to watever is supporting the centre of the Inverted-V. Just an extra loop of cord perhaps.

Steve are you using a fishing pole for the centre support of simply finding a suitable tree branch?

In any case the use of nylon cord as the strain releif for the links and possibly the feed point sounds like a good idea - I look forward to hearing how it goes Steve.

73 Ed.

String not good becomes damp very quickly and will short out.
Fishing wire nylon with good LB-age breaking strain should good as would have thought.

Can see where your coming from in trying to make the antenna simple as possible and lighter.

At moment am making portable antenna with a view of one minute its a vertical and then can quickly change it to a 40mb 1/2w end fed long wire that will run up the 8M Fibre glass pole and away at angle in one direction. and a equal length in counter poise via the Home brew 9:1 Unun for both antennas. Cause some times there won’t be room for said long wire and will have to resort to the vertical only. Be interesting see how this little fella works. But like the man says keep the end off the ground at least by what I reckon of 5 five or more

karl

But presumably not near the metal of the poles as there is a voltage peak at the end of the dipole yes?
I plan to use more nylon cord the extend the dipole for pegging out.

Yes indeed, I should have said nylon cord, thanks.
I plan to use a fishing pole (probably a sotabeam pole- I suddenly remembered the other day I actually have a fishing pole from my angling days, so excitedly went and (ahem) fished it out of the bag but it’s not much longer than a fishing rod, so too short)
Centre point wise I was thinking of a plastic (derivative) flat plate, but not like my prototype in the link, which was a bit fragile when drilling.(I’ll add photos actually to the original thread for completeness after posting this)

Yes my bad re string, I really mean the fairly slippy feel nylon cord.
Fishing line (I would favour braided) could be good for utra lightweight, though joining the two wouldn’t be as easy as the double fisherman’s knot would probably not work.

Its all a learning curve

I have here spider fishing wire 100Lb breaking strain .55mm and its braided got off internet its PE braided line fishing wire check your local fishing tackle shop they may have something similar. On end of my G5RV portable antenna for the car i use nylon rope as support wire ended off n a bungy rope to stretch it a little and keep the tension before it his the support pole

Now note the end support poles are ali poles from a tent that hold up the flap and are broken down into three sections easy to fold away and the bungy strap to add tension

karl

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I seem to remember from school physics that the breakdown voltage for air is 25kV / inch.
How high is the voltage on a half wave dipole with 5W of drive?
So yes, right at the end.

:wink:

I like that.

[quote=“MM0FMF, post:10, topic:11149”]
I seem to remember from school physics that the breakdown voltage for air is 25kV / inch. How high is the voltage on a half wave dipole with 5W of drive? So yes, right at the end.[/quote]

:smile:
Though I might contest that in the Blackies when I go up there is usually enough cloud conductivity in the air to break down much lower. But point well made and taken! :wink:

Also, do you have a link to an example of these?
I had been thinking of something like 4mm banana plus and sockets, but maybe the smaller 1 or 2 mm size.

Anderson power poles work for me

Terry G4POP

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I just use crocodile clips. I have been using them for 5 years and have had no problems.

And yes, I use nylon cord without any additional insulators to support the dipoles.

73,
Walt (G3NYY)

2 Likes

Thanks Andy, I’ll order those.

Thanks for the vote of confidence too Walt.

G4OBK links as used on my dipoles, as pictured today on I/TO-304. This link dipole has had about 60+ activations without a breakage.

Materials required: Phono connectors, wire, shrink sleeving (2 sizes), solder (inner is soldered to outer and wire), cut pieces of plastic soffit drilled to take the wire.

Works for me… sorry about the black thumbnail…

73 Phil

PS End termination: Tie wraps - soffit lozenge - shrink sleeving. Cord can be bought from most local hardware shops and flame fused to prevent fraying. Wire has quite thick insulation but is more flexible than most - 0.1/55 as used on instrument leads.

2 Likes

Ah brilliant Phil thanks.
I had seen someone (maybe even you) using phonos the other day but it had gone from the memory FAT. They are pretty good connectors. Used to draw about 20amps through some of those back in the day :smile:The cord you are using there is identical to what I plan to use.
That thumb looks painful too!

http://www.hobbyking.com/hobbyking/store/_31863__2mm_Gold_Connectors_10_pairs_20pc_UK_Warehouse.html?strSearch=connector%202mm
EUR2,11 for 10 pairs - the ones Andy pointed to appear to be the same but with heatshrink. These are from the Hobby King UK Warehouse.

Ed.

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UPDATE:

Well last night I finally got up to some clear space to build the antenna using this idea.
It worked well (unlike the **** brand new gas soldering iron).

Here is a finished dipole link. I don’t think you’ll get a lighter one than this, not even a cable tie required.

More waffle about it here, where more items recommended by you (with thanks!) all here can be seen in action.
http://g1ybb.uk/first-portable-lightweight-link-dipole/