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Antenna mast build & grounds

Posted: Wed Aug 21, 2019 4:48 pm
by Need4Speed
Now that my setup is nearly done I would like to pay it forward and share the details of my antenna mast and some of my build for anyone interested in something similar.

My 10' mast is mounted to a 33' old tv tower. The mast itself is made from a 10'; 1-3/8" chain link fence top rail. I also purchased 2 packs(4 total) of these panel clamps to attach the mast to my 1-1/4" tower leg.
I then cut off the end of the top rail that will accept another rail.
This piece will be the base and allow you to turn the mast to aim antennas. Once you mount the base tightly using a panel clamp you can slip the mast on it and pop another panel clamp on the mast to the tower to hold it in place.
While brainstorming this setup in Menards i figured if this didn't work, another idea would be these gate hinges bolted together but the panel clamps worked perfectly for my specific setup.
I then mounted my antenna brackets to the mast using a flat surface so they would both be in sync with each other(pointing the same direction).
Attached antennas to the mounts and installed 90° n connectors. Hooked up my 50' lmr400 cables to each antenna. Make sure they're very tight but don't strip them. Wiped them down with alcohol to remove any oil from my hands and wrapped with scotch butyl rubber tape. Then squeezed the tape together to make a nice waterproof seal. Then wrap electrical tape over the butyl tape so the butyl tape is UV protected. When wrapping you want to start from the bottom up overlapping to create a shingling of tape so the water can run off. There's good YouTube videos out there about weatherproofing coax.
I climbed my tower and mounted the base about 3' below the top to give my panel clamps plenty of bite on the mast. Now the hardest part is to climb the tower with the 10' mast, antennas mounted, and cables dangling off. I'd suggest getting help doing this unless you are pretty physically fit. The way i did it by myself was climbing each rung and reaching through the center of the tower rungs and grabbed the mast. That helped me keep balance and ensured i couldn't fall while reaching for the next rung.

Now for the lightning protection. I started by bonding each of my tower legs with a 5' piece of #4 bare copper wire to an 8' copper grounding rod. Before running the copper wire around the legs I wire wheeled off the galvanized coating down to bare steel. Then bonded/clamped them to each leg using stainless steel hose clamps.
Hose clamps not shown
Finished the base ground by burying the exposed ground rod.

This next part is *not* recommended per the lightning arrester manufacturers but I did it anyway. The lightning arresters are supposed to be outside before entering a building and grounded with #8 bare copper wire. I mounted mine inside because I wanted the least amount of coax connectors exposed to the elements as possible and the least amount of connectors as possible to minimize signal loss. So I repeat *do this at your own risk!*

I was aiming for a clean looking install inside of the house even though nobody will ever see it in my closet. (I'm ocd :D) I installed my lightning arresters in a 4 gang old work box that will go in my ceiling. It will house my ethernet cable and electric hookup for the router/modem as well.
I purchased these blank "build a faceplate" pieces at Menards. Drilled out 5/8" holes on 3 of the faceplates. This custom stuff on plastic parts takes some time and patience.

Re: Antenna mast build & grounds

Posted: Wed Aug 21, 2019 4:56 pm
by Need4Speed
Here's the box with arresters mounted.
Mounted in ceiling and hooked up.
Arresters bonded to tower.
Final assembly.
Have 1 more addition to add to the grounding that i will post this weekend when i do it.
If you have any questions feel free to ask!

Re: Antenna mast build & grounds

Posted: Thu Aug 22, 2019 8:55 am
by swwifty
Very nice setup! Thanks for sharing.

Re: Antenna mast build & grounds

Posted: Fri Aug 23, 2019 9:48 pm
by Need4Speed
Just finished up my final grounding today. Definitely overkill, but we get a lot of thunderstorms in my area. In my research static electricity builds up in the atmosphere during thunderstorms and that static build up degrades the gas charge in lightning arresters. So not only do these wick away static before they reach the arresters, butbthey are also add additional lighting protection(200kA rated).

So here's the part number. They were $43.25 shipped on ebay. Cheap insurance imo!
I started with the ground lead first to give me an idea of where to install the clamp end on the lmr400. The kit says to simply crimp the termination eyelets on but i took it a step further and filled the eyelets with solder first and pushed the wire in, then crimped/heat shrinked. Then wire wheeled galvanized coating off on tower mounting bolt area. The kit comes with 304 stainless bolts/lock washers/flat washers if needed. After mounting the ground leads this allowed me to make my marks on the lmr400 and cut/remove the outer jacket to expose the braided ground sleeve in the coax.
Applied butyl tape, then wrapped with 3 layers of electrical tape that all comes in kit.
Both wires complete. Fed some extra coax out to make the bottom of the loop lower than the ground straps for water to drip off.

Re: Antenna mast build & grounds

Posted: Sat Aug 24, 2019 7:44 am
by swwifty
that's an interesting grounding setup. My gas lightening protectors have N-connectors on them.

Re: Antenna mast build & grounds

Posted: Sat Aug 24, 2019 10:42 am
by Need4Speed
That's what mine have as well. Only non N is the router sma's. N connectors are the absolute best for our application since they have the best frequency range, lowest signal loss, and have excellent waterproof capabilities due to the sealing inside of the connector. I think these ground kits are intended for huge tower applications because the instructions say to space them out 200' apart on the tower :shock:
I wanted the best coax possible for the least amount of signal loss as possible. Times microwave was the best i could find. 10yr warranty with 20yr life expectancy. While researching them i came across this kit and it wasn't really expensive. I debated going with lmr600 but much more expensive for not too much more gain. I'm happy with the lmr400 results.

Gas lightning arresters are the cheapest protection but not the best. They have around a 5 year life expectancy. Also they can build up static electricity and discharge. Unfortunately if that happens, your equipment could be damaged.

Coil inductor type arresters are the best but extremely expensive(about $95/each). They never degrade and only need replacement when you take a direct hit. They also have less loss, 0.1 vs 0.4. Polyphaser is the company that i was looking into. Due to the overall high initial cost of my setup I passed on them. In 4-5 years, I'll change my gas charge ones to those. Now I have to upgrade my 2nd old asus n router to a gigabit router. It caps out around 95 over ethernet :cry:

Re: Antenna mast build & grounds

Posted: Sat Aug 24, 2019 1:23 pm
by swwifty
Need4Speed wrote:
Sat Aug 24, 2019 10:42 am
. Now I have to upgrade my 2nd old asus n router to a gigabit router. It caps out around 95 over ethernet :cry:
That sounds like a good problem to have, I have the same issue on my PFsense netgate hardware :)