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Building a coax entry panel

Posted by on November 14, 2023

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Overview:

Entry PanelA year or so ago, I got the idea of installing a loop antenna to help reduce some of my RFI.  Not wanting to follow some of my previous bad practices with more bad practice, I decided to totally rebuild my coax entry method.  This led to the creation of a patch panel, and that in turn led to the creation of a coax entry panel for bringing coax into the home.  What started as a project to install a receive loop, turned into a full blown shack rebuild starting at the antenna, and ending at the operating desk.  I laied out several thousand feet of radials under the 6BTV, then decided I needed to redo the coax feed, which in turn forced a rebuild of the entry panel, which in turn forced a rebuild of the coax feed method, and the introduction of a patch panel for RF.  That of course forced the redo of my operating position desk.  Most of this project is now finished, I used panduit, and carefully ran each cable in a neat and ordered way…  This is the story of the entry panel…

The Antenna farm:

Antenna FarmRight now I have a single 6BTV up, with plans for a 30 meter four square, a loop, and a 6 meter antenna of some sort.  So I needed at least three cables coming into the home.  I dislike doing things twice, and having to redo things from scratch, so I built an entry panel for six cables, each lightening arrested, and with proper grounding.

 

 

 

Location:

I am fortunate that my shack is about 15 feet away from the power service panel, and service ground.  That makes for a fairly easy path for grounding the station and entry panel.  I selected a NEMA 4 box, I found surplus.  Located a copper panel, and then started collecting all the parts needed to build a entry panel for coax.  First I needed a good ground, so I drove a 5/8th inch diameter ground rod below where the panel was going to live.  I did not use water, or anything else but a rod driving device I rented.  I also drove several  other rods to connect to the antenna farm later, along the coax route, and at the antenna mount points.

Antenna mount points:

Several years ago I decided to build an antenna farm, and did not want to be fighting cables, so I trenched the entire backyard, creating a tunnel system for cable distribution.  I am fortunate in that I have almost a half acre to play with for antenna use…

Grounding

Finished panel.

Finished panel.

I first decided on where I was going to bring in the coax cables into the home.  That helped me place where the entry panel would live.  I next pounded in a eight foot ground rod, directly under where the entry panel would be mounted.  I connected the new ground rod to the electrical service, via #4 bare copper wire, in order to create a single ground system for the home.  Eventually I will finish a full ground ring around the house.

The entry panel box

I scrounged a rather largish entry panel box from a friend who is in the electrical business.  There were a few holes in the bottom, but otherwise it was in good shape, and was NEMA 4 rated.  NEMA 4 keeps most water out, and is built for outdoor use.  I ordered a set of hole plugs to plug the existing holes in the box.  This gave me a water proof box I could mount outside on the house wall.

I had been saving a largish one eighth inch thick copper plate for a few years I picked up at a hamfest.  I took it to a metal shop, and had it cut to slightly smaller than the box ID.  I next drilled four holes in the copper, so as to mount it on the existing mounting lugs on the inside of the NEMA 4 box.  I sanded the top of the mounting lugs, and applied a star washer between the copper plate, and the box mounting lugs.  This connected the copper plate to the box itself, at 4 points.  That way, when I grounded the copper plate, I was also grounding the Entry Panel box.

My intent was to build up the copper plate with all the lightning arrestors, ground mounts, and anything else I needed on the copper plate, then mount the copper plate into the NEMA box, and finally mount the NEMA box on the wall of my home.  That way, I could build up everything inside, out of the weather, and near my tools…

I first purchased the lightning arrestors.  I used Alpha Delta arrestors, as they only needed a single hole for mounting, and they were substantially less expensive than other brands on the market.  I believe the Alpha Delta product does as good a job as any other arrestor, so I had no qualms about using them.  Next I laid out all the parts on the copper plate, and commenced to moving them around until I was happy with the layout.  I wanted all coax entering the box from the bottom, and in EMT conduit.

Why conduit the coax?  RFI protection.  The conduit is connected to the NEMA box, the NEMA box is connected to teh copper plate, and the copper plate is connected to a ground rid via about four feet of number six bare copper wire, and then to the electrical service, which also has a ground rod.  This places my coax inside a grounded two inch diameter metal piece of EMT pipe, as it runs into the bottom of the box.  This serves to weatherproof the connections, arrestors, copper plate, and everything else inside the NEMA box…

Back to laying out the copper plate– I next used a sharpie and added markings to the copper plate for every device I wanted to mount on the plate.  Each lightning arrestor, each ground lug, each mount point for wire ties, etc.  I took the plate to a friends place and drilled out all the holes using his drill press.

Now that all the holes were drilled, it was time to mount everything and see if it would actually fit in the NEMA box.  It did!  Next I mounted the plate in the NEMA box, and marked where the coax should enter the box from the bottom.  This completed the NEMA box portion of this project.

Water is NOT your friend

Why feed from the bottom?  Think water…  It rains a LOT where I live in Oregon, and I wanted all water to run away from the house, the box, and the coax conduit.  If you have an above ground power feed, take a look at where it enters your home.  Notice the drip loops so water is not allowed to run into your home via the power entry point, but drip off the cables into your roof, where the water is controlled, and move off the home, not into your home.  That is what I wanted as well– no vector for water to enter my home, or the NEMA box.  Everything is gravity assisted to run any water AWAY from the NEMA box, the coax conduit, and hence, my home.

Mounting the box

Entry Panel proposed diagram.I have to admit, I know very little about mounting boxes to the home, and drilling through walls to get wall plates where I want them.  Given the possible cost of a mistake, I elected to hire an electrician to mount the box, and drill the wall for the inside wall plate.  He made fairly short work of this project, and when he left I had a empty NEMA box on the wall, some EMT conduit on the wall, connected to the box, all weatherproofed, and ready for cables, and the copper plate.

Wiring the box

Now that the box was mounted on the house, I bolted the copper plate, with all the items on it, to the inside of the box.  All fit as I expected.  The ground lugs were right above the holes in the box for the gland fitting for the ground wire, and the holes for the conduit were where they were expected on the copper plate.  So I made the install of the plate permanent. Next I needed to pull some cables.  I ran a stinrg from the radio location to the lightening arrestors inside the box, via the route the cables would take from the radio to the box first.  Worked out to be eleven feet.  I next cut eleven and a half feet of RG8X, and ran that to make sure…  It was good, glad I added that extra six inches.

I pulled the cable, and then cut five more cables just like it.  I am fairly big on labeling things, so I labeled each cable with a label, and a piece of clear heat shrink over the label.  I used to work in electronics before I retired, and always labeled cables.  One of the things I learned was labels fall off after a few years.  So I started using clear heat shrink over labels, and that solved the problem.  Old habits die hard, and I still label everything, and cover the label with heat shrink…  After labeling the cables on each end, I bundled them, wire tied them, and ran them out of the shack into the junction box, and up to the NEMA box.  Why a junction box first, and not just directly into the NEMA box?  The NEMA box would have been very low on the house, so I needed to right angle the cable up to the box.  This also gave me a pull point straight out of the wall plate…  I routed the cable bundle in place in the shack, then tied it down so I could not pull it out of place.  I then pushed it through the wall and out into the open on the outside of the house.  Next I ran it up the conduct to the bottom of the NEMA box, and into the NEMA box.  I then terminated the ends of each cable with a high quality, PL-259, and routed it to the lightning arrestors.  I mounted four cable tie mounts on the copper plate prior to installing it into the box so I could create a cable run.  I ran everything in place, and added cable ties.

I was careful to observe the bend radius rules for RG-8X, plus some…  I never exceed bend radius limits for coax, that is a good way to smoke your amp, when the center conductor migrates to the shield, and provides a direct short on the coax.  If you are unfamiliar with the term “Bend Radius”, you should become familiar with it today!  I have seen far too many Amateurs ignore the bend radius rules when making chokes, and running coax.  If you ignore bend radius, you will be punished one day…  You have been warned!

I next needed to run six cables from the box to an intermediate point where my underground tunneling surfaces by the patio.  That took another six thirty or so foot runs of RG-8X, and another twelve high quality PL-259 connectors.  Those cables were labeled, and placed in an intermediate box.  All antenna run to that intermediate box, and then to the entry panel via the thirty foot EMT conduit to the entry panel.

Critter Proofing

Where we live we have a lot of rather aggressive, racoons, squirrels, and flying stinging, insects.  The stinginging insects like to build nests in everything.  Not wanting to open thge NEMA box one day to find a wasp nest, I decided to critter proof everything.  An electrician friend once taught me how to do this using Stainless Steel wool.  Note I used STAINLESS STEEL wool, not steel wool.  Normal steel wool will rust after a time, where SS wool does not.  I stuffed every entry hole in every conduit with SS wool, leaving enough to be able to remove it if need be.  I also found a plumbing pipe cover the perfectly fit two inch EMT.  I cut a small cross in it, stuffed SS wool into the EMT, then put the cover on.  That keeps out the stinging, and four legged critters out of the entry EMT.  I then added myet more SS Wool to the EMT entry points at the Entry panel as well, in the event something got past the first barrier…  Sometimes paranoia is your friend!

How does it work

Entry PanelGreat, I can add a new antenna, without ever having to crawl around, go under the house, or climb anything.  It takes only one person to connect a new antenna to the rig, and in general I am a lot happier to have things well grounded, lightening protected, and looking good…

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