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Call Sign : 26-SW-010 / 26-TM-087 Posts : 67 Times Thanked : 1 Join date : 2020-06-13 QTH or Location : Somerset Equipment Used : Kernow beta 4100 mobile for now...
Subject: Long wire portable antenna? Mon Jun 07, 2021 3:19 pm
Good afternoon guys.
Currently thinking about having a go at taking my xiegu g90 out portable. Got a good battery pack to use, only thing I'm missing and not to sure about is antenna. I'm thinking of possibly building my own long wire and then using my radios own built in tuner to tune it the frequency I want to use.
Now I'm not the brightest person going, I won't lie, but I'm guessing there's more to it than cutting X amount of wire, putting a plug on the end and then away you go?
So what I'm really asking is, can anyone break down the basics for me or know of any build guides? I'm guessing I'm probably going to need some sort of unun? And some way to chuck it up into a tree?
Any help would be appreciated?
Failing this, anyone got a link to where I can buy somthing? I'd much rather have a go at building somthing myself but if I have to buy then I'll have to buy.
Call Sign : 26-CT-3228 Ham M7VIC Posts : 3702 Times Thanked : 222 Join date : 2019-11-10 QTH or Location : Bedford Equipment Used : Various
Subject: Re: Long wire portable antenna? Mon Jun 07, 2021 6:41 pm
Nice to hear about you contemplating some portable/field work with your g90.
There's a couple of main options for antennas I can think of, one fairly easy to build the other really simple!
The first would be a long-wire as you mention or in reality a random-wire. The shortest you'll see is approx 20m long, (18.57m in reality), and cut in such a way that you get the lowest impedances on the most bands possible. (The other common type being shy of 40m long.)
You're right in that they are normally fitted with a 9:1 Un-Un. There's loads of info on the web about building such and I believe about £50 to buy a complete antenna system with one. (But where's the fun in that?! )
Regardless of what anyone says they also need a 'counterpoise' or some way of taming that RF for them to be effective. I believe some people are happy with the coax, radio and yourself acting as a counterpoise!! You also have to make sure that your radio can handle the tuning range required or carry a small ATU with you.
The other is the simplest system you can build and in my opinion the best in that you require no tuning so long as made for the bands of interest......
That would be a "Link-Dipole".
It's a simple dipole arrangement cut for various bands and you simply connect or link-up extra lengths for lower band usage. Might seem a pain to alter the dipole whenever you change bands but bang-for-buck a damn good system and easily home made.
Here's a link to a typical arrangement :-
He has some other useful stuff on his site so worth a bit of a read.
Anyone that can measure a length of wire out can build such antennas with consummate ease.
You may have to get yourself a fibreglass SOTA type pole for support but comes in really handy when there are no suitable trees about. You can also mess around with the dipole arrangement making a 'sloper' an 'inverted V', an 'L' or even zig-zag it across a suitably long fence....very versatile.
It means you won't be slinging wires up trees, sling-shoot or catapulting cord onto unsuspecting squirrels and more importantly trying your absolute damnedest to unravel your antenna from a tree! (Or even abandoning such a tangled mess...seen this a few times...littering bar-stewards!)
Anyway, there's bound to be a few other suggestions but that's the best I can muster out of this old brain of mine.
I wish you the best with it all and you'll have to let us know how you get on.
Call Sign : 43-CT-016 Posts : 287 Times Thanked : 20 Join date : 2019-11-17 QTH or Location : Perth Equipment Used : iCom IC-7610/IC-9700
Subject: Re: Long wire portable antenna? Mon Jun 07, 2021 11:18 pm
Tim Tom wrote:
Wow that's that's a lot of information there! Thanks Victor, I didn't think of a dipole but I'll check out that link as sounds good.
The other option, and one I use, is an EFHW. This is still a long wire type, but cut for resonance on the longest band, and using a 49:1 matching transformer rather than a 9:1 unun. Not really any more difficult to build than a random wire, quite flexible in how you use them (vertical, sloper, inverted v, etc.) and the big advantage…..resonance on all higher bands that are harmonically related, unlike a dipole.
There’s a few tricks to building them depending in frequencies you want to use, but generally if you are an SSB operator, you won’t need a tuner on the main bands.
I run an 80-10 at home, and a 40-10 for portable.
Youtube has heaps of build videos, and Steve Ellington has a heap of background info on his channel, as well as a decent transformer construction guide.
Last edited by 43CT016 on Tue Jun 08, 2021 9:01 am; edited 3 times in total
Call Sign : 26-CT-3433 Posts : 160 Times Thanked : 6 Join date : 2020-04-06 QTH or Location : Hull Equipment Used : Midland Alan 88s + crt 9900+5/8 gain master Age : 54
Subject: Re: Long wire portable antenna? Tue Jun 08, 2021 9:19 am
Hi Tim ,I can recommend the gwhip 432.its 12m long good for 40 20 10,set up as a sloper,fed from the ground only needs one support tree or pole. Under £100 and good to go straight out of the box. regards mark