Sunday, 17 May 2026

Rusty DUAL 23cm antenna restored - for a while anyway.

My 36 element 23cm Dual antenna from Antennas and Amplifiers works very well but suffers badly in the salty air blowing off the North Sea just 2 miles away. I bought it in May 2021 and by January 2023 the steel parts were rusting, though of course the boom and elements are aluminium alloy and remain in good condition up to today.

Bubbling under the coating on the 36 element Dual in January 2023
It was just getting worse over time and I knew that I would have to do something. I do not think this is structurally significant right now, but it could be in the long term. Those steel parts are very thin and will rust through eventually.

The solution I hit upon was to take it apart completely (36 bolts), clean the coating and rust off the steel parts, coat them with Hammerite paint, and then put it back together again (36 bolts). Lovely job. Cleaning the metalwork involved using wire brushes on an electric drill, just the sort of thing I do not want to do. So it took ages, not because it was really that hard, but mostly because I did not want to do it in the first place.

I am not the only person with this problem. I have heard reports of these parts rusting on other Dual antennas. I have also heard that Duals now come with stainless steel parts, apart from the boom and elements of course. Until I have seen it for myself I shall reserve judgement on that.

Eventually it got so disreputable looking that I decided I had to get stuck in.

Central section of the 36 element Dual partly completed
The photo shows the repaired side on the left and the original on the right. The mast bracket is also coated steel but I decided to leave it for now as it is not about to fall apart.

You may be wondering why I used green Hammerite. Answer: because that was the colour I could get. It should not affect the radiation pattern much.

This is not a long term solution. The Hammerite will not last too long either. 

In the meantime I fell back on my reserve 23cm antenna, the 28 element Wimo:- 

28 element Wimo
The Wimo does not look great at only 1.5m long but it is only 2dB down on the Dual and it kept me going for several months. Good enough to get across the North Sea to Norway, Sweden and Denmark plus into France, Germany and more.

The Dual is now finished and back up. It looks a lot better than the Wimo and gains me those extra 2dB.

36 element Dual restored
From ground level I cannot even spot that the steel parts of the antenna are now green.

I wonder where I will be able to work on 23cms now that this antenna has been restored and replaced on the mast?

73 Jim

GM4FVM

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3 comments:

  1. Rick (GM4JIB)18 May 2026 at 01:06

    Would the manufacturer supply a mod-kit of the new stainless steel parts? Worth an email I would have thought. Nice to see you back.

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  2. Jan, OZ9QV19 May 2026 at 02:43

    Hey, Jim,
    Good to see you back.
    I am working on getting a 23cm up and running.
    At the moment I am using a vertical omni, and get regular signals from the SR1KOL beacon 270km away.
    In your direction the path is up-hill, but perhaps one day.
    I am planning on a horizontal yagi, possibly the 28 element you are using, too.
    Vy 73 de Jan, OZ9QV

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  3. GM4FVM24 May 2026 at 15:05

    Rick, great to hear from you and thanks. I could ask Goran for new parts, but I have more plans for 23cms so watch this space !!!
    Jan, thanks. I should be able to work you on 23cm as OZ is my best direction from here. Maybe not on the vertical! I read your blog back in November and I was hoping you might go far something like that yagi. The 28 ele yagi from Dual is a good size with plenty of gain. I would welcome a sked, but as you are slightly too far for aircraft scatter we would need some tropo over the North Sea. See you soon.

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