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I have a VHF satellite antenna that has a PCB mounted below the driven elements containing phasing harness connections. The PCB is shielded from direct rain by the element mounting arrangement, but it's base is visible below. The antenna is designed for short term portable use.
I want to make it more weatherproof for use permanently outdoors, receive only. Element joints I can seal using self-amalgamating tape, but it's the PCB that's the problem. I want to pot the whole base of it to the elements and mounting arrangement so it is completely sealed.
I've thought of non-acidic silicon sealant but I don't know it's affect on RF. I see Jaycar has a polyurethane potting compound, but curiously the manufacturer doesn't list it on their website.
https://www.jaycar.com.au/polyurethane-p...d/p/NM2016
Has anyone used this or can suggest a better compound?
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How about a coating of epoxy resin?
Cheers
Nev
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VK3LU Wrote:How about a coating of epoxy resin?
Cheers
Nev
My earlier outdoors use of epoxy resin always seemed to result in degradation over time, along with discolouration, crumbling, cracking etc when exposed to direct sunlight/UV so I now stay away from it. I have used the non-acidic silicone sealants for various antenna purposes that have soldered joints but haven't used it directly on a built-up PCB. You could always apply a liberal spray coating of PCB lacquer over the PCB + components (both sides) before encapsulating it with the sealant in order to prevent any corrosion. By the way, the sealant shrinks over time so use extra.
Let us know what the outcome is as plenty of others may eventually need the same answer themselves.
Doug VK4ADC @ QG62LG51
http://www.vk4adc.com
This Forum is only going to be as interesting as the posts it contains.
If you have a comment or question, post it as it may trigger or answer the query in someone else's mind.
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During some googling I saw mention of not using resins outside for just those reasons.
I guess by using a non-acidic silicon sealant it can be removed later, something which would be useful.
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Hi Damien,
VK3AMZ advised me, and have seen for myself that hot glue makes a very good weather shield and has no effect to at least 1296MHz. I built a W6PQL style feed and the RL did not change once the glue was applied all over the connector and feed point solder connections. My 1296 yagi has been out in the weather for a few years now and has not changed characteristics.
If I did the same again I would devise a way to get a lot of glue sticks hot in a very short time.
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Spray it with multiple layers of clear acrylic?
Nev
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Thanks Nev; I will do that as an insulating barrier before potting it with anything I think.
G'day Lou; Hot glue as a potting compound sounds good, and I've had the same problem - the darn stuff cools too quick
My Jaycar gun just doesn't seem quite up to it.
Use a saucepan and melt as many stick as as you want plus a few extra.
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VK2HRX Wrote:Use a saucepan and melt as many stick as as you want plus a few extra.
Wow! I'm glad VK3FJEN doesn't read this forum. :o
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How about beeswax? Doesn't go hard and brittle.
Nev
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Many thanks Justin - I'll look into that product.
