Sealing coax connectors.

nevesjerry

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Hello everyone,
Can any of the members clarify a question I have regarding properly sealing coax connections. Am connecting a coax male BNC connector to the bottom of the magnetic loop box which is a W6LVP Magnetic Loop. Do I start winding the electrical tape immediately from the BNC connector and move on down the coax for about 3 inches or so OR, start winding the electrical tape from the bottom of coax and on up to the BNC connector? Any help appreciated. Basically I want to keep water out.
Regards to all,
Jerry
 

paulears

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If you want to do it properly, then a wrap of lecie tape under tension, followed by a layer of self-emalgamating tape, followed by a final leccy tape layer will keep the water out. General preference is to start at the lowest point and go up with the usual tape, but the waterproofing is from the self-amalgamating layer really. Ordinary electricians tape goes hard in UV light and cracks when the sun bakes it, so soon lets water through. I did an experiment in UK weather with two antennas, and tape only lasts about a year. Cutting it off reveals water ingress, hence why you need the solid lump of rubber that the other type provides, with the protection of the leccie tape.
 

bchappuie

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I would use Gorilla tape, and wrap from top down, with half loop covering, so each wrap covers half the one above it. Gorilla tape is a bit thicker, and more durable. Get's you closer to butyl tape.
 

WB9YBM

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If you want to do it properly, then a wrap of lecie tape under tension, followed by a layer of self-emalgamating tape, followed by a final leccy tape layer will keep the water out. General preference is to start at the lowest point and go up with the usual tape, but the waterproofing is from the self-amalgamating layer really. Ordinary electricians tape goes hard in UV light and cracks when the sun bakes it, so soon lets water through. I did an experiment in UK weather with two antennas, and tape only lasts about a year. Cutting it off reveals water ingress, hence why you need the solid lump of rubber that the other type provides, with the protection of the leccie tape.
For water-proofing, I've usually sprayed the tape with Krylon. Stay away from that gooey sealing tape--I've had bad luck with that.
 

WB9YBM

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I would use Gorilla tape, and wrap from top down, with half loop covering, so each wrap covers half the one above it. Gorilla tape is a bit thicker, and more durable. Get's you closer to butyl tape.
Does it dry out when exposed to UV? I've had that happen with cheap electrical tape, and it looses it's grip. Although more expensive, I've had the best luck with 3M brand.
 

jaspence

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I have been using Coax-Seal for many years. My last antenna cable change was after five years and except for being hard to peel off the old seal (it was still very sticky and pliable), there was absolutely no sign of water or any other corrosion in the connector. The cable enters the house through a patch panel that is also exposed to the weather, and it was equally clean and dry. It conforms to almost any shape and sticks to almost anything.
 

paulears

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If you check on what is often a requirement for commercial towers or cell phone installations, you need something that properly seals - so the rubber based products that turn after a few weeks into a solid lump of rubber always win, but need protection. Sticky tape always performs poorer. I've had to use that nasty goo impregnated cloth tape on some commercial installs when it's a site rule, but the stuff plumbers use to keep water in, often works well keeping it out. PVC tape goes hard over time, so the nastiest methods last longest, but are a pain to do? Your call really. Anything that is difficult to get off in a couple of years was a good choice - but look at how a few turns of PVC holding a feeder cable to a pole always falls off!
 

mmckenna

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For hobby use, it's up to you.
Industry standard goes like this:
Make sure you connector is clean and dry before connecting. Many non-hobby grade connectors for larger coax include a section of adhesive lined heat shrink tubing. If your connector doesn't have this, it's a good idea to put it on. It'll not only seal the crimp well, but it provides some strain relief.

Start a few inches below the connector, wrap some good electrical tape (Scotch 33+, not Harbor Freight). Wrap up towards the antenna. Each pass of tape should overlap the previous wrap by 50% (Half lapped). When you get to the base of the antenna, make sure you are not blocking any weep holes. Change direction and wrap back down to the starting point. This process is called "Half lapped and back".

Next, take your Butyl tape, start just below where the tape stops and wrap the entire connection with a slight overlap. Stop when you get to the antenna base, remember, don't block the weep holes. Then go back and by hand, mold the butyl tape in so all voids are filled and it's a smooth covering. There should be no visible seams.

Finally, do the tape wrap again. This time, start at the antenna base, wrap down with the 50% overlap until you get past the butyl tape. Then reverse direction and wrap back up to the antenna base. Resist the urge to pull on the tape to break it. Use scissors or a razor blade. When you stretch the tape too much, the plastic stretches and thins out the adhesive. That's where it'll start to unravel.

If you really want to go hardcore, follow all that up with a cote of Scotch "Scotchkote".

That's the method you'll see used at commercial sites. Having done it this way for a long time, I've never had a connection leak. I've pulled old antennas down and dissected the connector and found no water intrusion after 20 years of installation.

Yes, it's a pain. But it works. You can save money by doing a half way job, and it may work, or it may fail and you'll end up having to not only replace the connectors, but likely the coaxial cable, too. No doubt you'll get some hams that claim they never waterproof connections and they've never had an issue, but that's usually just someone confusing luck with skill. For braided coaxial cable, any water intrusion will result in that water wicking down the cable. The water and copper will corrode and make a mess. You'll not only damage the connector on the coax, but likely several feet of coax. The corrosion can also damage the connector on the antenna.

You can purchase a kit like this and get what you need to do several connections: https://www.theantennafarm.com/catalog/commscope-221213-1956

If you keep your eyes open on e-Bay, you can often find those kits even cheaper.
 

ScubaJungle

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Just another idea - there's a coax sealant you can buy for about $5 a roll on amazon, its like a black putty that you wrap around the coax connector like tape, and then mold it into the correct form with your fingers. It seems to work well from my limited use of it.
 

prcguy

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Speaking as a commercial broadcast, commercial satellite uplink and two-way radio engineer with countless outdoor connections that had to be perfect, the proper way to do it is what mmckenna says above. That will last a lifetime and will also allow you to easily remove everything if you need to get to the connector in the future. The key point there is the layer of Scotch 33+ type tape as a first layer and if you put any of the super sticky tapes or goo directly over the cable and connector you will be hating life when it comes time to remove the connector.

For hobby/home use in most areas several layers of Scotch 33+ is completely adequate and can last 20+ years. There is no need for coax seal or gorilla tape or spray paint, etc, just do a good multi-layer job with the 33+. Its best to end the last layer of tape as you are wrapping uphill as that will leave the seams in a position where water will run off and not sit in the groove between wraps. Always cut the tape at the end and don't pull hard to break it, its more likely to unravel if the end was stretched and torn.
 

krokus

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The method mmckenna listed is almost identical to what we used on shipboard connections, for the US Navy. We also used some cold shrink tubing, which would be an expensive overkill for most other uses.
 

trentbob

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I have been using Coax-Seal for many years. My last antenna cable change was after five years and except for being hard to peel off the old seal (it was still very sticky and pliable), there was absolutely no sign of water or any other corrosion in the connector. The cable enters the house through a patch panel that is also exposed to the weather, and it was equally clean and dry. It conforms to almost any shape and sticks to almost anything.
Just another idea - there's a coax sealant you can buy for about $5 a roll on amazon, its like a black putty that you wrap around the coax connector like tape, and then mold it into the correct form with your fingers. It seems to work well from my limited use of it.
As the dinosaur that I am who does not like change I have been using the same product coax- seal for decades. It's imperative however that you wrap tape around your connections first before applying and molding the sealant.

If you have to remove the sealant it is a goopy mess but with the tape it will easily come off unwrapping the tape.
 

rescue161

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We always wrap a layer backwards first, so there is no adhesive in contact with the connectors. Once that initial backwards layer is on, we follow mmckenna's instructions.
 

mmckenna

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We always wrap a layer backwards first, so there is no adhesive in contact with the connectors. Once that initial backwards layer is on, we follow mmckenna's instructions.
I've heard of that, and it sounds like a good idea. I keep meaning to try it.

My brother in law was cleaning out one of his warehouses and ran across a bunch of sealing kits. He gave them to me. I usually don't need that stuff at home, but the big 2" wide rolls of electrical tape sure are nice to have.
 

rescue161

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It works great when you have to remove a connection. Once you take apart a connection that just has B-sealant stuck all over the connector, you will go to great lengths to ensure that you never have to go through that again. I've taken apart connections that have the layer of tape stuck to the connectors and it too leaves a goopy mess, so I try to ensure that the connectors remain shiny and clean if I ever have to take it apart.
 

mmckenna

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Denatured alcohol usually works very well for removing adhesive residue. I scored a few of my N to 7-16 DIN adapters that way from a shut down MetroPCS site.
 

W5lz

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For amateur use I've never found it necessary. I also don't leave them in a puddle of water.
 

WB9YBM

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I've had the worst luck with something called "Coax Seal": my connectors always end up corroding. It's been worse than no sealant at all!
 

rescue161

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Sounds to me that water is getting in from somewhere else, possibly from the antenna itself. If you are trying to seal a coax connection and the antenna termination is open to the elements, you are going to have problems. I always laugh when I see someone coax seal a J-pole and leave the connections at the antenna elements unsealed.
 
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