[amsat-bb] Re: why not to buy an M2 antenna
normanlizeth at gmail.com
Wed Dec 11 03:10:38 PST 2013
My times technologies T100 says the switching block failed. I am not
worried about cosmetics. Cosmetics don't get grid squares.
On Tue, Dec 10, 2013 at 3:46 PM, David Metz <davemetz at machlink.com> wrote:
> The damage shown in the photos is simply the plastic (my guess is it is
> Delrin) breaking down from UV exposure. Back in the 80's I built my own
> circular polarized antennas for 70cm and 2M for AO-13. Having a lathe I
> made some parts from white Delrin (a nylon like material). After about ten
> years it showed the same UV damage. Note that the black plastic element
> insulators in the photos are not cracked. The black pigment used in the
> element insulators apparently protects them from UV. After learning this
> lesson I started using the black Delrin for my home brew antennas and have
> had no problems with UV damage. All that said, some plastics are more
> resistant to UV than others. I have two M2 antennas in use for terrestrial
> use and after ten years of being up in the elements they are both working
> well. Note that the UV damage may not have gone all the way to the core of
> the component yet. If it is still mechanically intact (and just looks
> awful), it can be salvaged by coating it with a thick black sealant and
> covering that with black electrical tape.
> --73-- Dave WA0AUQ
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