Longwire End Fed antenna and FC-40 tuner

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Joined: 10 Jun 2021, 13:25

Longwire End Fed antenna and FC-40 tuner

Post by chr0nik »


I've decided to remove a EFHW antenna I had and put up a end fed long wire antenna attached to a FC40 tuner as I wanted to try to get 160m to 6m The tuner is right outside the window of my shack and the cable goes up 9 metres on a budget flagpole across 14 metres to a 12m Spiderbeam.

The issue that I'm having is that even though 40m, 20m and the higher bands tune around 1:1.5 to 1:1.1, 80m tunes around 1.2 through the whole band but the RF goes crazy and disconnects all of the USB devices attached to my laptop. I have around 3 ferrites clips on each end of all of the cables in the shack and a 10m+ counterpoise which keeps the swr low enough (I've tried extending it and cutting it and the swr increases and it does not tune.

I'm also unable to do any tx on FT8 on WSJT-X as it appears that I'm not heard (I have the cable attached from my FT430 using a USB sound card. I can see activity on RX but nothing on TX. I'm not sure if this is an issue with the antenna or with WSJT-X as I'm unable to be heard on my GainMaster on 10m.

What can I do to reduce the RFI and to be heard on FT8? I understand that I might need to add radials for 80m but how long and how many is recommended?

Thank you.
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Buick Mackane
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Re: Longwire End Fed antenna and FC-40 tuner

Post by Buick Mackane »

Common mode RFI is a well known issue with random / long wire antennas. I just got rid of one for this very reason and replaced it with a EFHW, Basically the reverse of what you've just done and iv'e not had any RFI issues since. Plus it doesn't require a tuner. If you don't have room for a halfwave 160m endfed then you could look into adding a loading coil.
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Re: Longwire End Fed antenna and FC-40 tuner

Post by Ant »

Make an RF choke, get an FT240-43 core and wrap as many turns of coax through it as you can, makes a massive difference.
Shack, noun, a small building, usually made of wood or metal, that has not been built well - Oxford Dictionary
A shack (or, less often, shanty) is a type of small, often primitive shelter or dwelling - Wikipedia

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