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propper silicone to use on antennas

B

BOOTY MONSTER

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i cant find the thread/post now , but i recall a while back someone telling me not to use silicone that has a strong vinegar smell to it on aluminum . i think it was something about it eating or causing corrosion on the aluminum . can someone tell me if im remembering that right and/or let me know what to look for when getting some silicone to use on aluminum and copper surfaces ?
 

You are correct, sir. The acids will corrode aluminum. Even the fumes will cause corrosion. Get a silicone approved for aluminum engine components. Should be available at most auto parts stores.
 
I believe it is acetic acid that is in most of the 'normal' silicone caulks out there. Shouldn't be used for sealing grommets close to RF connectors or inside housings with components in them either.
 
so something by permatex at auto supply stores that the package says is approved for aluminum is safe and will work ?
 
Use High Temp RTV Silicone if it's going to be used outside. It will last forever and is pretty easy to remove. You can get it at the auto parts store.
 
BOOTY MONSTER said:
i cant find the thread/post now , but i recall a while back someone telling me not to use silicone that has a strong vinegar smell to it on aluminum . i think it was something about it eating or causing corrosion on the aluminum . can someone tell me if im remembering that right and/or let me know what to look for when getting some silicone to use on aluminum and copper surfaces ?
Click to expand...

BM, the problem using such silicone, as you describe, is not so much one of corrosion to the aluminum and destroying your tubing. The problem with the Acetic Acid part of the formula is a chemical reaction that eventually defies the bond of the silicone to the aluminum and undoing the seal. Aluminum oxide is also soluble in water and washes away. When this happens there is a void created at the point of the seal and you can see this as the seal ages.

Aluminum cleaners are often made of a combination of vinegar or acetic acid and water, and larger quanties of acetic acid are almost always shipped in aluminum containers so it is not the aluminum you have to worry about.

So, if you want a good seal with alumuinum, don't use a sealer with acetic acid.

What are you sealing on your antenna?
 
thanks again guys . ill be getting some "Permatex® Ultra Black® #598B" .

"What are you sealing on your antenna?"

well , my current plan is to use two 4 ft sections of 5/4 solid plastic decking (no composite /no sawdust) since i can get that free . a 4 ft plastic 2x4 would cost $24 :( . ill double up the two peices of 5/4 and that will be plenty strong for my area , one piece might actually be strong enough , but i like to over build stuff . im gonna get a peice of aluminium sheet about 12 inches square and make a wide H shaped cut in the middle about 5 3/4 to 6 inches wide with the two sides about 2 1/2 to 3 inches high on the ends . then bend them up so the two sandwiched 5/4 boards can slide up into it , thatll be what my ground elements will attach to . the bottom leg of my tuning ring will also attach to the middle of one of the turned up lips . ill also drill a hole and put a rubber gromet in the plate for my coax to come through (with a few wraps of tape around the coax at the hole ........ just because ......) .

i plan to drill holes around the plate for half inch bolts with nice fat washers and a lock washer to go in to hold the ground radials , ill put a 2 inch or so fish hook bend on the end of each one to catch the bolt and keep the washer level and provide extra surface contact between the element and the plate . the reason for silicone is using stainless steel nuts and bolts in the size i want to use add$ up very quickly . so ill use the sealer to cover the top and bottom of the bolt/nut and washers and the edge of the element so no moisture can get to the bolt . ill be using #5 hardware for its strength and because its much much cheaper , but it isnt weather proof so ill need to protect it .

thanks again guys :)
 
I really wonder how much of this debate is real and how much is just followed because someone said so. The reason I say this is because waaaaay back when silicone first started being readily available the ONLY kind was the smelly stuff that smelled like vinegar. I still have some on an aluminum antenna that has been there for over twenty years and I have to cut it off with a knife. No voids under it and the corrosion is not as bad as the aluminum that was exposed to the weather. I also have used it on coax connectors and after cutting it off after a decade of use the connectors were still shiny. Use what you want but I'll use what I have on hand at the time.

BTW we use the smelly silicone on stainless, aluminum, and bronze dies at work and the only corrosion we see on the aluminum is from the chemical bath they are subjected to. The area where the silicone is, is in better shape than the rest of the die.
 
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My friend who was an EE in the RF field told me about the issue. They used to use silicone to fix tuning coils etc on proto boards and found out the hard way about the corrosion. The topic came up because I had a few vehicle mounts with grommets I sealed with silicone, where the brass and copper on the antenna connector right next to the sealed holes had corroded something fierce.
 
I used some black permatex on my maco v58 and the current aluminum ground plane. I used it to seal the joints of the tubing to keep water out and the match from going up.

Ive had no problems with either one as a result.
 
What do you do to the beam ends and where element's slide together? Do i use the same thing and the stuff. Also the element's have red rubber caps that slip over the ends but nothing on the end of the beams. I was thinking i might drill some small holes in the bottem of the main beam To let water get out . Thanks.
 
silvereagle1 said:
What do you do to the beam ends and where element's slide together? Do i use the same thing and the stuff. Also the element's have red rubber caps that slip over the ends but nothing on the end of the beams. I was thinking i might drill some small holes in the bottem of the main beam To let water get out . Thanks.
Click to expand...

What are you calling a "beam"? Do you mean the boom, that part of the antenna that the elements connect too? Hard to tell as first you ask "What do you do to the beam ends and where element's slide together?" which sounds like the ends of the elements but then you say "Also the element's have red rubber caps that slip over the ends but nothing on the end of the beams. I was thinking i might drill some small holes in the bottem of the main beam To let water get out" If what you call the "beam" or "main beam" is in reality the boom then leave it alone. You do not need anything on it to keep water out. Water will not stay in it and will run out the uncapped ends. 99% of the antennas out there have lost their boom end caps as well as most of their element end caps too over the years.End caps serve more to keep the wind from howling as it blows across the open ends than it does to stop water ingress.
 

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