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QRPguys no-tune EFHW?


#21

I give a big thumbs up to an EFHW for maintaining an ultralight pack. It’s worked very well for me.

Barry N1EU


#22

Well, 3 dB related to the theory may already be, but probably not so relevant in comparison with another practical portable (multi-band) antenna.


#23

Joe,

At the end of the day, I would say that whatever well known antenna design you pick, will work, as long as you have some patience and it is properly designed. Among these choices you have to make a smart decision utilizing versatility, ease of deployment, weight, and size. The no tune EFHW is great in all categories except versatility. You need separate wires per band which is a bit of a PITA. Ease of deployment is usually not bad but for 40m and especially the lower bands that’s a long wire.

The qrp guys are coming out with a trapped EFHW for 20-30-40 if you would prefer a kit. Those three bands are 90% of my SOTA contacts, maybe more. That kit will have it’s own disadvantages, namely narrowbanded nature on 40m and trap loss on 30 and 40. Neither should be enough from preventing your 4 contacts.

I’d recommended their vertical kit as well. Base loading adds some loss on 30 and 40 but again, not even close to a deal breaker.

But with your heavily treed summits these SMALL sacrifices in efficiency are easily outweighed by the benefits to the the important stuff (versatility, ease of deployment, size and weight). There are plenty of summits in other parts of the world where you have enough room for bulky linked dipoles, multiple supports, etc but in tight trees these other options make more sense. You just need your 4 contact for a valid activation. Optimize your SSB settings in the kx2, use some compressor, and dial up to 10 watts and you’ll have a better signal than the guy with 5w and the linked dipole.


#24

BIG disadvantage IMHO: it’s going to be a major pita to prune this antenna to resonance on the 3 bands. Mark my words . . . been there. Otherwise, should be a great antenna choice!

Barry N1EU


#25

Mine is ready to go, just need to get the analyser out and mark off each band.



#26

Excellent! What’s the lowest freq you’re going to try to tune? Also, what’s your plan as far as elevating the clothesline winder?


#27

Well I’ll try for 80 with the KX2 internal tuner, it’s a little short perhaps at 100ft. I’ll use my telescopic pole to elevate, either as a sloper, or with the orange plastic piece I can use it as an inverted V.


#28

Hi Joe,

$200 is not a lot of money. A 2 course meal with drinks for 2 (not a pie with chips and a beer) plus a 10% tip won’t leave much change out of $200. You might get a plumber to come to your house in normal hours for this but any work will be extra. Oh and remember it is a deposit, the full report would be much much more.
The lunch is your best option.

The best antenna is whatever you have in your pack. It might be 3 dB down on a better one but an antenna in the air is worth 100 under the bed.

Good Luck
73
Ron
VK3AFW


#29

Hi Brian,

3 dB makes no difference? Not true. When your signal is S9 plus it may not matter but when your signal is on the noise level an extra 3 dB on your signal will give you the contact. In these time of generally poor propagation every dB on a summit counts.

Red herring alert. How many dB does it take to move the FT817ND S meter from 0 to 5?

73
Ron
VK3AFW


#30

Hi Joe,
My wife always knows when a significant activation is being planned. I am in the back yard checking out a new antenna.
My most used antenna is the SotaBeams link 80/40/30/20 m dipole.
Next up is an OFHWD. I have them for 160 m, 80 m, 40 m.
Third most used is a dipole fed with 300 ohm ribbon. Either about a half wave on 60 m or 30 m.
Used a couple of times, G5RV.

These are mainly for < 3,000 km. For DX I favor ¼ and half wave verticals with 2 or 1 radial respectively. Parallel tuned cct with taps for matching half wave. More radials are a nuisance to deploy and get in the way of other hikers.

I’ve run tests on a 4 band commercial EFW in a park and it has been rejected in favor of the link dipole or tuned doublet.

The Link Dipole is no harder to deploy on a summit than an EFW, IMO.

73
Ron
VK3AFW


#31

Hi Andy,

Having replied to several others I owe it to you to make a post QRT response.

One modern behaviour that distresses me is the default of asking someone, anyone, for basic technical advice. For antennas the ARRL Antenna Handbook is very good place to learn about antenna basics. Minimal maths. Reading references seems to be a lost art. Even Google will supply more info than you can read in an afternoon. Check the credentials of the writer of course.

Not checking previous threads and resurrecting yet another dead horse is part of the same disease.

On this post G8TMV has pointed to a fine posting by AA5TB on making the EFW work. Bookmark it. You can then refer the next enquirer to it. I do not feel motivated to extract the numbers from it.

Asking about peoples experiences and preferences is of course legitimate and to be encouraged.

I should start a new thread for this but WTH. The best portable ATU’s do no better than 90% efficiency, dropping to 50% on some frequencies. Google is your friend for this. No need to ping me for making a statement without a spreadsheet and diagrams.

Broad band preset matching efficiency is inversely related to size. Should be obvious - small core, thin wire, unknown quality capacitor, etc.

When I build Baluns and rf transformers I make 2 and connect them back to back to check for loss and frequency response. Educational, especially if you can get two commercial ones for test.

73
Ron
VK3AFW


#32

Now that is just not true. Because of the end fed design and the fact it does not need to be balanced, you can route it through thick tree cover and undergrowth much more effectively than a balanced dipole with two legs to worry about. Also, you can have individual lengths of wire for each band. With the link dipole you have to fit the wire for the largest band. I’m not sure how you could come to the conclusion that they are equally easy to deploy, especially on the fully treed summits Joe and I are dealing with…


#33

Hi Heinz,

The QRP guys do have some good “stuff”. However commercial availability does not mean something is really good or even good.

For an example I refer you to the "Joystick "antenna once advertised in the RSGB magazine and elsewhere… As a young naive fella I bought one based on the glowing testimonials. Complete snake oil. Old hands warned me to buy something else but I wanted to believe. There are still people out there that think it might have some magic as a Google will show.

That said if you are wedded to the end fed concept then use it. Nothing I say is likely to change this but you should not think it isn’t a compromise.

73
Ron
VK3AFW


#34

Hi Evan,

Probably you will never agree with me but yes it is true. Think it through.

I put up a squid pole and unreel a quarter wave for the lowest band I want to use on each side. Half the length to keep out of the trees as compared to a full halfwave held up at the end.

If you suspend your wire in the centre the installations are equal.

I have deployed on summits where the trees were 10 m saplings 2 m apart so this in not armchair theory.

73
Ron
VK3AFW


#35

Don’t misquote me, Ron, I actually said:

“Usually” because relatively few contacts are on the noise level, and if your antenna plus rig can detect the background noise then that 3dB doesn’t matter.


#36

I wish!!!

Too many over the last few days have been at the (high local) noise level when I’ve been on a summit. Not all summits are quiet Brian.

Are we not at 100 posts yet so this thread will close? (please).

I think a a couple of people have pointed out that it’s difficult to get the “ideal” antenna to a summit, have it weigh next to nothing, set up in no space at all (because the siummit is busy) and be directional to filter out noise and QRM - so we will always end up with a compromise to try and fit as many of our needs as we can. It can never be perfect.
“even a bad antenna is better than no antenna at all” - most times anyway.

73 Ed.


#37

I’ve been lucky in that respect, I’ve never activated a really noisy summit (touch wood!) - but I would guess that if the noise level is that high a few dB loss in the antenna won’t matter, a more efficient antenna would bring in more of the noise as well as more of the signal.


#38

Cheers for that Ron. That is one the best hand waves I’ve seen in a long time and I do offer you “respect dude” for going for it: respect :+1:

I’ve pointed people at the AA5TB site in the past and used his ideas myself until I left the matchbox on Knock of Crief or Torlum Hill some years back. :frowning:


#39

I have no deep grasp of antenna theory, I just use whatever works. However, one reason I use an endfed is that it requires no coax. The 10m of RG174 that comes with a SOTABEAMS 4 band linked dipole contributes 1.2 db loss on 20m (according to DXWire), so the true difference between that and an endfed is only 1.8 db (rising to 2.1 db at 80m). That said, there is nothing like a nice pile-up, so I am not totally sold on the “it’ll get you 4 contacts” mentality. When I do an activation with OE6LKG, we like to take his 4 band dipole and a 50w linear (no atu needed). Personally, I find a 10m mast, feeder and wire to be more difficult to set up on a wooded summit than an endfed, as the legs must be fairly evenly spread out to get the SWR down. Whereas, a Fuchskreis will tune up in all kinds of orientations. When I’m multi-day trekking, a 600g antenna and 1.5kg mast are out of the question, and 2db difference is irrelevant to me. Then, of course, there is the excellent out of band rejection provided by a Fuchskreis, on a noisy summit the difference over a normal dipole can be huge (to my ears anyway). OK, a Fuchskreis is a not quite the same as the impedance matched endfed that is the subject of this thread.
de OE6FEG / M0FEU
Matt


#40

I built mine this weekend and tested it with less than great results. For the sake of testing, I tried it with a 28.8’ radiator on 20m. I could not get swr lower than 5:1. I figured maybe I’d wound the toroid incorrectly (or not got the enamel off the wire etc) so I redid it. Results were better but still not acceptable – 4:1 at best.

I’m guessing the 12’ of coax I am running isn’t providing enough braid to act as a counterpoise. They don’t provide any specs as to what they tested with, so I emailed. Their response: 25’. That’s not going to work for what I have in mind unfortunately (tiny ultralight kit). Back to the drawing board.