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My club has a well used Motorola branded StationMaster UHF repeater antenna that needs to be sanded and recoated. Besides the surface, the antenna is in very good working order so we're not interested in recommendations to replace it.

I've seen many recommendations to use products like U/V resistant polyurethane or any non-metallic U/V resistant paint. What I'd like to know is if any of you have actually had good results refinishing an antenna and what specific products you used.

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    $\begingroup$ Comments are not for extended discussion; this conversation has been moved to chat. $\endgroup$ – Kevin Reid AG6YO Sep 27 '17 at 18:36
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    $\begingroup$ @SDsolar You're still making suggestions in comments; that's not what they're for. Either write a proper answer, or take it to the chat room that's been created. $\endgroup$ – Kevin Reid AG6YO Sep 28 '17 at 16:21
  • $\begingroup$ @SDsolar We all know that you mean well and are a great asset; but I fully agree with Kevin. As the tour states, "Use comments to ask for more information or clarify a question or answer." (Having said that, I've been guilty of being a little chatty myself! :-) If you (or anyone) have questions or comments about this, please feel free to ask them in this chat room. $\endgroup$ – Mike Waters Sep 28 '17 at 16:40
  • $\begingroup$ Now we know exactly what kind of antenna is being discussed. And at the price now we know why restoration is better than replacement. But we still don't seem to have an accepted answer. $\endgroup$ – SDsolar Oct 2 '17 at 5:01
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I have had good success with Rust-Oleum 206999 Marine Topside Paint. I prefer the white gloss version to minimize mold growth and to promote ice slippage.

Proper surface preparation is important. Most weathered fiberglass will develop a mold growth in the "pores" of the fiberglass. In addition, the original finish may contain a wax substance. So start with cleaning the surface with a fiberglass cleaner. Then sand the surface smooth, finishing with a 120 grit paper. Remove all sanding dust using a tack rag. Then apply a thin layer of Rust-Oleum Marine Coatings Primer.

Once the primer has dried, apply the Topside paint in a thin coat. Apply a second coat 24 hours later if needed.

I have found this paint to have enough elasticity to survive the constant flexing that the radome experiences on the tower and I have yet to repaint a radome after 10 years of exterior exposure.

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We painted our antenna radomes with Aerodur, but it's a $200/litre fast curing two part paint that is quite dangerous to breathe. It wasn't chosen for its electromagnetic properties, just its toughness, but gave no trouble, two or three coats, up to 6 GHz.

I'd recommend any auto body paint, like a 2K two part paint. With the right primer and surface preparation it will stick well and last a long time in the sun. We also used these for less military applications, and when we needed a gloss white finish which we couldn't get in Aerodur.

We used a lot of black paint for antennas, but perhaps it's safer to avoid it, it is possible they contain (macroscopic) carbon which could affect the antenna.

You definitely don't want to load the antenna with any substantial thickness of plastic, like putting it in a new pipe. A layer of good paint is fine, any thickness, but a plastic pipe is not ok, might upset the tuning.

Finally, you don't want to seal it airtight - make sure you don't paint over the drain hole in the bottom of the original radome. A large volume needs to breathe and drain condensation, attempting to make it airtight will just cause it to suck in moisture from somewhere unexpected.

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