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Antenna Cable for EFHW Antenne / EFHW Antenne Vertical

Hi Sota Community,

in the next days i will test a new EFHW Antenne for 40m/20m/10m for Sota Activation on Summits, on which i cant use my regular Linked Dipole for 40m and 20m.

https://www.dj4wd.de/ega40lv.html

My Question is, what HF Cable from the TRX to the Antenne should i use?

For my Linked Dipole i use Hyperflex 5 which has 0,36 db attenuation on 20m per 10m Cable.

a RG 58 has 0,6 db attenuation on 20m per 10m Cable.

So the different is 0,24 db which an Hyperflex 5 ist better.

Is this an Reason to use Hyperflex 5?

TRX is an Yaesu FT-817 with about 7 Watt on 20m.

The next question is, ist it a good idea to use this Antenna as a Vertical Antenne and hang it down a Tower like this

https://sotl.as/summits/DM/BM-344

What do you think?

Thanks for your Help.

Michael, DC8YZ

2 Likes

Hi Michael,
Decision on which cable to use also depends on the length of it you’ll be using.
In my setup, I use less than 1m of RG58, so I really don’t care about cable losses for such short length.
As for having an EFHW vertically hang from the top of a fishing rod, I think it’s a perfect way to use it and take advantage of the low radiation angle that configuration will give you.
73,

Guru

4 Likes

I think RG58 would be fine, or what ever you have. Attenuation will be small. I use 5m of RG58 with mine.

I wouldn’t hang it vertically down a metal tower. Perhaps a sloper towards a fibreglass mast would be better, or vertical or sloping to a nearby tree. Or even fix a fibreglass mast to the tower horizontally and have the wire horizontal along the pole with the end dangling down vertically, but well clear of the tower.

73, Fraser

1 Like

Thanks Guru

Thanks Fraser

Hi Sota-Community,

In den nächsten Tagen werde ich eine neue EFHW Antenne für 40m/20m/10m für Sota Activation auf Summits testen, auf der ich meinen regulären Linked Dipole für 40m und 20m nicht verwenden kann.

EGA40LV (de) DJ4WD LabShack Antenne 3

Meine Frage ist, welches HF-Kabel vom TRX zur Antenne soll ich verwenden?

Für meinen Linked Dipol verwende ich Hyperflex 5 mit einer Dämpfung von 0,36 db auf 20m pro 10m Kabel.

ein RG 58 hat 0,6 db Dämpfung auf 20m pro 10m Kabel.

Der Unterschied ist also 0,24 db was ein Hyperflex 5 besser ist.

Ist dies ein Grund, Hyperflex 5 zu verwenden?

TRX ist ein Yaesu FT-817 mit ca. 7 Watt auf 20m.

Die nächste Frage ist, ist es eine gute Idee, diese Antenne als vertikale Antenne zu verwenden und sie so an einem Turm aufzuhängen?

SOTLAS 7

Was denken Sie?

Vielen Dank für Ihre Hilfe.

Michael, DC8YZ

I use a 10m length of RG174 coax as the feeder for my 60/40/30/20 linked dipole and 40/30/20 EFHW. The attenuation is spec’d at <1dB at 10MHz (30m band). I run a maximum of 10W (CW). Ten metres is long enough for me to sit in a sheltered spot away from the wind whilst the antenna is out in the open. The RG174 coax on a plastic winder weighs 187g and occupies little space in the rucksack.

3 Likes

THanks G8CPZ

Yes even RG/174 is good enough on lower HF bands and really light
It’s getting flaky on 10m - and forget it for VHF/UHF

I remember a story about a CB shop where they kept getting customers complaining of high SWR indications with cheapo antennas - they would “solve” the problem by selling them a 25m length of RG/174 and telling them not to cut it - just loop it if it’s too long. Result - low SWR !

2 Likes

I use it up to 28MHz (10m band).
This online calculator …
https://www.qsl.net/co8tw/Coax_Calculator.htm
… gives the attenuation for a 10m length of RG174 (for 10W)
0.82dB @ 10MHz
0.98dB @ 14MHz
1.41dB @ 28MHz
1.92dB @ 50MHz

73 Andy

2 Likes

Hi Andy

As ever, if it works for you that’s fine

I did have a bad batch of RG/174 once that performed much less well than that - I think that as with all coax it varies by brand

Cheers
Rick

Hello Michael,

you won’t notice a difference of 0.24 dB when operating. Remember one S-Unit is 6 dB.
Also, what @EA2IF wrote needs to be considered: with an EFHW you could use a very short cable which could compensate the slightly higher loss of RG 58.

73, Roman

Thanks Roman

Hallo Michael

This is my normal SOTA antenna equipment:

I also use a few meters of RG174, which go to the antenna via a W1JR balun. I need the cable to find a comfortable place to sit when it is not at the feed point of the antenna.

When I’m on the summit with PA, I have a tuned EndFed instead of my vertical wire… the rest stays the same.

73 Armin

1 Like

Using calculator is good to select coax you might want. I always measure actual losses of made coax as quality of connectors and how they are attached might have significant impact on actual losses value.

Pls note that, -1.41dB equates to 20% of lost power, plus losses in transformer you might end up with only 50% of your power being radiated.

1 Like

To your second question… of the construction of the antenna:
A lot of people have built their endfed as L antenna. That is ok.!

About your picture: I would not have built up the antenna in the middle of the way, in order not to let the displeasure of others on me and those the radio operators at all arise.

I like to go a little offside. If it has a bench - fine… if it has no, I find something else. I always have a small insulating mat with me

In the situation, which is to be seen on your picture, I would have mounted the mast probably to the support of the back of the bench. I do that with Velcro straps (others with tension straps).

… I am a friend of the KISS - principle :wink:

73 Armin

2 Likes

VIelen Dank Armin

Hi Marek thanks for your help. That means every endfed Antenne is not so good like a Inverted V Dipole with straight feed. Cause the Transformator of the Endfed has loss ?

Ist this correct?

Thanks Michael

There is loss in everything.

A dipole with coax feed has a loss in the coax (dielectric loss). This is given in charts. There is also loss due to SWR miss match. But there is a lot of cheap, substandard Chinese coax on sale so to be sure you should measure it.

An endfed matching unit will have loss. A lot of authors on here have to done a lot of work to try to reduce those losses. The loss you will achieve when you make a matching unit depends on the components matching what the author used and the quality of construction.

Either way there will be some loss. The aim is to get the matching unit loss to be no more than the equivalent coax loss and hopefully better.

I use RG174 for coax fed dipoles. IMHO it’s OK for use up to 14MHz and at 18MHz it is starting to get too lossy in the 10m length I use. My 12/10m 1/4wave and 10m delta loop use about 4m of RG58 to help keep the losses down. I would not want to carry 10m of RG58 with me!

Which is best? Which has lowest loss? It depends. So build an EFHW and link dipole and compare them. They don’t cost much to make and there is lots of fun to be had building and experimenting.

8 Likes

How long is this run of coax going to be? I never need more than 3m for my end feds, so RG174 works fine.

Have you increased TX power via the service menu? If so, how’s it working?
73 Matt

2 Likes