Tuner or resonant EFHW?

[angelodp]

Just getting started using this radio. For POTA, would you recommend a resonant antenna or a tuner? EFHW are pretty much all I use but due to different configurations I don't always get the same SWR on a hilltop as I do in my back yard.

Does this radio work with a tuner? Would it have to be an automatic tuner? Nothing in the docs.

If you suggest using a resonant antenna please let me know what has worked for you. I am very partial to end feds. Someone on another forum suggested a vertical but I dread the idea of lugging around a tripod, coil, whips, counterpoises, meter, etc.

[elTrauko]

Hello, simple dipole inverted V, and since I only work 10 meters it is a very convenient antenna. Sometimes I use EFHW.
And it is a very interesting radio.
Suerte y buenos Dx's
Cesar CA7OKD
73

[angelodp]

Hello, simple dipole inverted V, and since I only work 10 meters it is a very convenient antenna. Sometimes I use EFHW.
And it is a very interesting radio.
Suerte y buenos Dx's
Cesar CA7OKD
73

What EF wire do you use, and what tuner?
Thanks,
Angelo

[elTrauko]

https://www.hfkits.com/product/mini-imp ... d-antenna/
https://qrpguys.com/qrpguys-end-fed-wire-antenna

wire:
https://www.hfkits.com/product/experime ... ire-1-mm2/
and speaker cable
and I am considering buying sotabeam cable soon

And also one that I did according to the information from qrpguys and it is the one in the photo

[SP9TKW]

Most efficient EFHW antenna will have Fusch matching unit, like one linked in previous post from QRP-Guys. However, this solution requires re-tuning every couple kHz to keep SWR below 1.5:1 needed by (tr)uSDX, especially with 13V+ supply.

Alternative is autotransformer 49:1 or 64:1 but as you already noticed SWR will change with setup configuration and place. Efficiency is a bit lower than Fusch but you do not need re-tuning and you can switch from band to band quickly. I do SOTA so chasing S2S is dead easy.

On thouse ocassions where SWR is bigger than 1.7:1 I use ATU-10 which maintanins for me flexibility of changing bands quickly at the cost of small efficiency decrease.

Check Manuel's YouTube channel where he tries different winging methods in order to make efficient transformer. There is a lot of examples of very low efficiency transformers on the forums and facebook. KN5L method is very efficient, very close to Fusch, but it's tricky to accomplish well. Next on efficiency table is autotransformer and then classic crossover with twisted first two turns.

For QRP and POTA I would suggest FT140-43 as KN5L 28:4 turns or autoransformer 21:3 turns, this will give you option of 50-70W if you decide to take PA with you. For hikes etc... lighter version could be accomplished on FT82A-43 or supper light version by Adam K6ARC (YouTube).

Random/Long Wire has flexibilty of many bands (incl WARC) but has even lower efficiency, so at QRP level you migth not make as many QSO as with EFHW, I would not expect problem with activating park and minimum 10 QSO. Saying that propagation is improving, so these issues become less and less relevant unless you want many DX contacts.

In case of DX QSOs you should consider EFHW4010 (20mtr wire) setup as Half Square. There are some videos on YouTube (eg. G5TM)

GL 73 Marek

[angelodp]

Very interesting discussion, revelatory in many ways. I did not realize the (TR) experiences so many difficulties with SWR above 1.5 or so, and at various power levels.

I'm going to go with El Trauko's (and several others') suggestion to get the QRPguys antenna, which they claim provides <1.5:1 SWR across the advertised bands. I already have 4 or 5 49:1 un-uns but I've never been able to duplicate what they claim so I'll order theirs.

Thanks for all the thoughtful, helpful responses.

The (only) thing I hate about this hobby is its complexity, which is also the main reason I love it.

[RF_one]

> And also one that I did according to the information from qrpguys and it is the one in the photo

Thanks for supplying this hi detail image. The toroid could perhaps be spaced from the (ground potential) BNC flange by 3-5mm, e.g. with self-adhesive taped foam, to minimize potental dampening or other influence ?

[DL1DBY]

I use 41m or 21m EFLW antennas with an 49:1 UnUn from HFkits.com. It is the "Mini"-Version but still capable of 100 watts, so with a 5 watts (tr)uSDX the core is far from saturated. I also frequently use an Elecraft T1 tuner and ground counterpoises. On vacation I forgot the T1 tuner at home but I managed to shorten the EFLW and got an SWR of 1:1.2 or little less. Performance was great. So a tuner is certainly not required and since then I usually leave it at home. But it is surely necessary to adjust the length of the antenna every time the EFLW antenna is deployed.

But I often prefer a so called City Windom Antenna which requires no tuner and under normal conditions no adjustment of the length of the antenna. It is a little heavier, though.

73 Dieter DL1DBY

[reytek79]

https://www.hfkits.com/product/mini-imp ... d-antenna/
https://qrpguys.com/qrpguys-end-fed-wire-antenna

wire:
https://www.hfkits.com/product/experime ... ire-1-mm2/
and speaker cable
and I am considering buying sotabeam cable soon

And also one that I did according to the information from qrpguys and it is the one in the photo

Friend, which model of this core of the photo?

[elTrauko]

Amidon FT-83-43

[reytek79]

Amidon FT-83-43

did you get a good swr on the bands from 40 to 10 meters with this core?