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Antenna for SOTA or travelling

I believe any “random length wire” is going to need an ATU to be able to be used - if your rig has an ATU built in, this is worth considering, if it hasn’t then that’s another box and cables to carry with you, so I’d avoid the solution.
It also requires some way to support it, but I suppose you could get a “throw bag” and look for a suitable tree branch to use as your support if you want to avoid the extra volume and weight of a telescopic fibreglass fishing rod.

73 Ed.

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At the occasion, I would like to introduce my version of the EFHW.

Without any tuner it works on the bands 80m, 40m, 20m, 15m and 10m. With ATU also very good at 60m, 30m, 17m and 12m, so on all 9 bands between 3.5MHz and 28.5 Mhz.

The 9m coaxial cable serves as counterpoise. At 80m, the 20m long antenna wire connects to 50 ohms of the Unun, otherwise at 2.8k ohms.

If there are a least two trees on a summit, I throw the end with 10m rope with the ring nut into the branches, let it down and pull the Unun with the antenna wire up. Likewise I do it with the other end.

If there is only one suitable tree or if I have to use a pole, I install the antenna as inverted vee or a slooper.

The antenna works surprisingly well at 80m. During the day I often reach Lothar, DL3HXX over 200km, Fred, DL8DXL over 300km or Michael, DJ5AV over 500km. Tnx for listening to my call!

73 Chris

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Just 20m long? also for 80m?

20m are 1/4 wavelength for 3.5Mhz. Like a ground plane.

73 Chris

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Actually - and I know this from experience - a 20m long end fed antenna with a simple tuner will even get you contacts on 160 metres. Look at it this way, if the antenna is only 50% efficient your signal will drop by less than a standard S-point, and usually this will be not be noticeable.

One of the joys of amateur radio is that we can experiment. In time you can try out all the above suggestions and find out which one suits you best.

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A 10m wire works great on 40m and 15m bands. You can put it inside a fibre glass rod for better performance.

Hello
I only have the drawing (attached). Hugo (CT7AOV) uses one and describes how “… works quite well …”.

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Antenna-rig here: random wire + 1:9 UNUN + tuner.
Works.
Andy

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Thanks for your suggestions…

For the 80m band, I now connect my 20m long EFHW antenna wire to the high-resistance connection of the 1:49 unun, just like on all other bands up to 10m and use the tuner from the KX2.

It works surprisingly well. Yesterday I was very happy about the second S2S with Leszek over more than 500km on 80m in ssb.

73 Chris

If you have the space one of the SOTABeams dipoles https://www.sotabeams.co.uk/four-band-portable-dipole-antenna-system-band-hopper-iv/ is a no-compromise antenna that works great from QRP to 100 watts. I have perfected deployment and retrieval technique - both take about 5 minutes and by dropping a couple of sections at the bottom of the mast I can relink for a different band in a minute.

Regards, Mark. M0NOM

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I recently made a Inverted V runs off a 10m squid pole. its a linked res V DP for 20m and 40m and 80m is linked again via loading coils and ATU. But like you said Sotas can be restricted areas.

Then just take one element of the DP mount vertical as add CP wires at least 4 X 5m lengths i use 8 X and run it vertical. No Baluns or Ununs required. Very simple to build including loading coils but be idea to build ya self a machine I build to wind coils and a decent LCR meter.

Karl 2E0FEH KERNOW