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HF linked dipole - finished

Finally got my HF linked dipole for 20 and 40m finished today. I needed more space so I headed for a local beach in Hoylake, Wirral.

Made contact on 14mhz, 1 x SOTA(EA2WX/p and 1 x CQ call from Poland(SQ1REX)
Top of the 6m pole needs some guys as this bends over with the weight of the ferrite at the top.
Fed via RG58 from a FT-875D via an ATU. But looking at SWR, I don’t thinks its required, but I think I might pack it just in case.

Cheers
John
m0vaz

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I can highly recommend Richard’s video. HOW TO PUT UP A PORTABLE ANTENNA | SOTApole - YouTube I now do exactly what he recommends. In very strong winds I may add an additional long guy from the very top directly into the wind. I had been diligently setting up my linked dipole in a straight line, thinking it was important, it doesn’t matter.

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I took the thin end section out of mine as its very fragile. Most poles were designed for smaller fish - not strong winds. I then glued in the small eye to the next section down. It is much more steady now.

As for erecting the mast I have rarely use guys.

I got about a foot length of black plastic waste pipe just slightly wider than the butt end of the pole. One end sliced off diagonally to make a sort of point/sharp end. Pressed or knocked into the ground with a stone or your foot and you can simply insert the butt end into it. You can also do this in a stone cairn or other stoney place which means you are not struggling to hold the pole in p,lace whilst you secure it. When yyouve got the pipe firmly fixed in the rocks you can lift and insert your pole in the pipe. The pipe takes all/any pressure or damage which may damage your pole.

As an improvement I made a shortish slit along most of the length of the pipe using a jig saw. Its wide enough so that when pulled out of the ground you can poke out with a tent peg any soil/peat inside it if you need to… You can also cut the ground/bottom end to look like the teeth of a hole saw - obviously with much bigger ‘teeth’, so that you can screw into or through hard ground.

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My suggestion, guy the pole with a collar and nylon coords around 1.5 - 1.75m. You can then get the pole vertical which results in the weight of the antenna being less likely to bend and strain the pole. Using the antenna to guy the pole will result in stress/strain fractures in the wire/joints. Also clip the coax to the pole and make sure the weight of the coax is not supported by the joints/connectors. There’ll be less waving in the wind and less flexing and less chance of the coax fracturing.

I think it is 15 years since I was last on the beach at Hoylake. (Former Upton resident).

That aside, the satisfaction that comes from rigging a few wires together and finding it works as expected is difficult to measure. Next on your list should be a vertical or two for the higher bands as the sun continues to wake up.

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You shouldn’t need an ATU. It would be worth buying (or borrowing!) an antenna analyser. The NanoVNA isn’t too expensive and does a good job. I built a 15/17/20m linked dipole and tuned it with my NanoVNA without a lot of difficulty.

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I use the Comrade 600 pole these days. I took out the very top section and glued it inside the second from top section to make it a bit stronger. Maybe you could lighten your feedline by using RG174 and BNC connectors and tie the feedline in a couple places to the pole rather than have it hang as something else to catch the wind. I rely on my FT817 vswr meter in the radio if the radio is happy with the load it will give full power. I think the link dipole made for the bands you want to use is a great antenna and I have used it almost all the time on SOTA, and tested or tried all kinds of antennas in my yard on QRP or chasing other SOTA ops for fun.
Regards.
Ian vk5cz …

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The bending of the rod is not due the ferrite weight but the weight of the RG-58.
I practically have the same setup as yours. 6m high fishing rod, FT857, linked dipole from 28 to 7MHz and the heavy RG-58.
To avoid the belding I reccomend you atach the coax to the rod with 2 or 3 velcro tapes or also you can sorround the coax a couple of times on the rod. With this method you also avoid the stress on the conection point.

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You could also remove the ferrite at the feedpoint, it isn’t essential and it adds considerable top heavy weight. Never had a balun on any SOTA dipole, I always use thin and light RG-179 and have no problem with SWR or the need to use an ATU. Main SOTA /P bands for me 20m through to 60m using home brew link dipoles using thin silicon wire on a 5m lIfe’s a breeze travel pole.

73 Phil

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A bit slow replying to the messages, yesterday was a day of Motorsport and lack of 4G stopped replies! (But didn’t stop the SOTA chasing :slight_smile: on HF)

@mm0fmf
I do need some guy’s - something I will have to look at.
I was thinking of some velcro straps to attach the coax to the pole.

I heard you are an ex-wirral person. Blame Brian ZRP (same radio club)

There is some satisfaction from building/rigging up a few wires to get on the air.

Any suggestions as to verticals for HF? - I think I would prefer a vertical over a dipole, especially for the busy summits.

@MW0KXN I will take a look at the video & @m6gyu thanks for the tips on the plastic tube idea.

@MW0KXN I will take a look at the video & @m6gyu thanks for the tips on the plastic tube idea.

@m0wiv I do have and I did take a NanoVNA with me to the beach - a very handy tool.

@vk5cz & @jp3ppl I used RG58 as I had a 100m role hanging around

@g4obk cheers for the advice, I used the ferrite as it came with the kit. Maybe a Mk2 is on the cards, with no ferrite and some RG174/RG-179

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I mange the weight of the RG58 cable by using a short length of 20mm PVC conduit. I find it pushes down nicely on the coax and takes the weight off the upper sections.
YMMV

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Hi John,
If you want to avoid having to carry a very tall pole (at least for 20m and below) and supports (including guy ropes which can be an issue on busy or small summits), you are probably looking at a loaded whip. You can of course build your own but if you want to save some time, there are several commercial options available. I currently use a Komunica HF-PRO-2-PLUS-T with a self-modified photo tripod and 8 radial wires. (Komunica can also supply a tripod/radials kit). This all packs into the inside of my medium-sized rucksack (it would fit in a small one as well). Set-up/take-down time is about 15 minutes and works well (but not quite as good as a dipole) on 40 & 20m. It actually covers 80m through 70cm. It’s light enough that it stays in the pack as my backup antenna even when I take other antennas with me.

73 Ed.

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1/4wave GP. 10/12m fit a 5m mast. 15m just fits a 6m mast. This is for the classic arrangement with 3 radials sloping down from the feedpoint to ground at 45degs (use Pythagoras and basic trig to work out lengths and angles). In mine, the radials meet the ground.

NIST’s WWV time signal uses 1/4wave GP antennas. Each antenna is 1/2wavelength tall. The top 1/4 is the radiating element, the bottom 1/4 is isolated and used to raise the radiating element 1/4 wavelength above ground. There are 9 equal length radials, each of which slopes down at 45deg, each radial is sqrt(2)/4 wavelenth long. This is a little longer than the classic formula which suggests 1/4wavelength long (WWV length 0.3535 wavelength vs 0.25 wavelength). Antennas are fed with hardline coax and no coax crosses another coax feed.

That’s a commercial setup. The improvement of 9 vs 3 radials is measurable but probably not worth the effort for SOTA.

I’ll post some pics/measurements for mine.

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RG 174 coax such as https://uk.farnell.com/multicomp-pro/pp000620/coaxial-cable-rg174a-u-black-100m/dp/2356780 ?

Thanks DD5LP, I will take a look at the link/page.

That coax is awfully cheap.

Cheap due to being not good quality. Or cheap due to misprint?

Yes! It’s copper coated steel inner conductor which is OK. A roll of Belden RG-174 (a known quality brand) is £68 for 1/3rd the length. It just seems too cheap.

You may want to consider buying a length of RG-174 with connectors already fitted. RG-174 connectors are fiddly if you don’t have a crimp tool. Being a cheapskate I put off buying a crimp tool for far too long. People like Sotabeams will sell ready made cables for not much more than the component costs and were using some quality RG-174 cable in the past.

Like all things, there’s always far too much to consider :wink:

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Both Belden and Multicomp (Google suggests Farnell is the owner behind Multicomp) coax’s are both copper coated steel.
I have the crimping tool.
Cheers
John