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OT: Grounding a tv antenna

Bill D

Diamond
Joined
Apr 1, 2004
Location
Modesto, CA USA
Off Topic; I an installing a roof top tv antenna. Everything I read says to ground the antenna cable before it goes into the house. Problem is my ground rod is 50 feet away on the opposite side of the house. Seems like a poor idea to run a ground cable under the house for this safety feature.
Would it be okay to instal a separate ground rod at the antenna entrance. Or will this cause noise issues since the tv will be attached to a separate ground point. I suppose I good run a wire between the two ground rods to tie them together.
Very seldom any lightning here, never touches ground just cloud to cloud.
Bill D
 

rons

Diamond
Joined
Mar 5, 2009
Location
California, USA
Reading is nice and I do a lot of it. The ARRL Handbook is a good read.

I installed a TV mast on my roof. I used one of the drain pipe air vent pipes.
Did the same thing with my ham radio antenna.
Very strong base with this method and a automatic ground.

Have pounded two separate 8' ground rods in my career. Enough is enough.
 

52 Ford

Stainless
Joined
May 20, 2021
I have a little experience with this... Dedicated ground is fine in my experience. You can get lightning arresters and whatnot to go between the TV/device and the coax cable.

Honestly, I don't think noise is THAT big of a deal with TV antennas, nowaday, since it's a digital signal versus analog.

To the best of my knowledge, I get almost every channel within a 60 mile radius, and I'm using a pretty small antenna. Plus, I'm in the woods surrounded by tall trees and the tree tops are a good 40 feet above my antenna.
 

52 Ford

Stainless
Joined
May 20, 2021
Reading is nice and I do a lot of it. The ARRL Handbook is a good read.

I installed a TV mast on my roof. I used one of the drain pipe air vent pipes.
Did the same thing with my ham radio antenna.
Very strong base with this method and a automatic ground.

Have pounded two separate 8' ground rods in my career. Enough is enough.

They make ground rod adapters for rotary hammers. Just gotta pull the trigger. I've driven ground rods with a hammer and it isn't something I'd do for fun.
https://www.homedepot.com/p/Milwauk...S-Plus-Ground-Rod-Driver-48-62-6031/306319981
 

FredC

Titanium
Joined
Oct 29, 2010
Location
Dewees Texas
Have pounded two separate 8' ground rods in my career. Enough is enough.
An electrician showed me a trick for installing ground rods. Takes about a quart of water. Put the hammer aside and by hand start a pounding it in and pulling it out. When you get it an inch or two deep pour some water in and keep going. Pull it out every six inches or so and add some more water. A lot of times I get the 6 or 7 feet deep and finish up with the hammer. I had an installer install lightning rods and he used some kind of electric hammer tool to put them in at 45 degree angles because he dd not want to climb a ladder to do it. I ran ahead of him and put a lot of them in 4 or so feet because I did not like the idea of angling them in.
 

steve-l

Titanium
Joined
Mar 2, 2012
Location
Geilenkirchen, Germany
Grounds are a very complex issue, especially when it comes to RF earths. The old saying of grounds are not the same the world around is very true. Every building needs a single power entrance point and at that point your local ground should be established. That ground bus should be as short as possible and to that bus all your safety grounds should connect. That same ground bus should also connect to an earth ground outside. That ground could be an array of interconnecting ground rods in an array. The advantage of this is a lower impedance and a wider bandwidth to earth. Do not connect additional ground rods to any other point outside of the local ground bus at your entrance point, otherwise you create a ground loop. The loop occurs because electrical energy travels at almost the speed of light. It is not instantaneous. In fact it is approximately 2 nanoseconds per foot. This can result in huge voltage spikes during a close lightning strike as well as electrical noise.
 

GregSY

Diamond
Joined
Jan 1, 2005
Location
Houston
Ground rods are a lot like motor oil.....there is a massive amount of bullshit swirling around them.

When I built my shop, I was determined to read up and install a no-compromise ground rod. The more I read, the more I felt misery creep into my life. That's because there is an ocean of conflicting information, all written by experts. It was this experience that prepared me for COVID.

So.....drive a new ground rod where you need it. If driving a single 8 foot rod is beyond your abilities, give up on the entire project...you don't deserve to watch TV. But I'll also add that if you don;t use any ground at all, there's a fair chance you won't notice any difference.
 

Tony Quiring

Titanium
Joined
Nov 5, 2008
Location
Madera county california usa
Do you have lightening in your area?

Imagine a falling doughnut from the top of anyenna to the ground.

That is the path for your ground to be effective.

The coax needs to stay on same bath until it enters your home and needs to be attached to the ground cable that is between ground rod and antenna where it changes direction.

If you seldom have lightening I. Your area and there are taller trees nearby then not really needed.

You may get by with arrestor inside

Sent from my SM-G781V using Tapatalk
 

Scottl

Diamond
Joined
Nov 3, 2013
Location
Eastern Massachusetts, USA
With the correct choice of spark arrestor/decoupler there should not be any noise issues as the return will not be directly earthed.

Also, the theory re coaxial cable is that due to skin effects at higher frequencies the noise runs on the outside of the shielding braid while the signal return runs on the inside adjacent to the dielectric.

If you still have concerns add some clamp-on ferrites to the cable.

PS: If you have cast iron drains the vents make effective earth connections.
 

rons

Diamond
Joined
Mar 5, 2009
Location
California, USA
The real test of your installation is how it will hold up under a Russian EMP detonation over your city. But you are in a low probability area.
In my case Moffett Field and Lockheed Missiles and Space center are within the vicinity. My power stereo set.

Look in the ARRL Handbook. There are drawings of proper bonding methods.
 

EPAIII

Diamond
Joined
Nov 23, 2003
Location
Beaumont, TX, USA
I seriously doubt that you can get any noise problem by grounding the coax. Except, of course, during an actual lightning strike and then, you probably will be worrying about bigger things.

I would use the shortest route possible to run a heavy ground cable from the bottom of the mast to a ground rod. And let the mast extend a foot or so ABOVE the antenna. As for the coax, I doubt that any cautions that you can take will either protect the electronic circuit it is connected to or provide any additional safety to your person than the grounding provided by the TV/receiver it is connected to. If you really want to, ground or attach a spark gap device at the point where it enters the house and ground that to the same ground rod via the shortest path possible.

Lightning protection depends on providing a VERY LOW RESISTANCE path for it to take. Running a wire to the other side of the house is counter productive. Keep it SHORT and use heavy gauge wire.

Lightning is a very strong electrical impulse and once it gets into the coax, there is likely no stopping it as far as protecting the circuitry is concerned. Best bet is to provide a much lower resistance path down the mast and the ground rod. It probably will not save the electronics where only a few tens of Volts will be a disaster, but you and your family will be well protected by that low resistance path and the additional, low resistance path of the house wiring's safety ground through the chassis.

As for noise, you will never see it. Digital signals either work, or fail completely. It is called the waterfall effect: good until it fails and then it very quickly fails completely. Just keep the connections tight and put "rubber" boots or some silicone sealer over the outside connections to prevent corrosion. Also use drip loops so the rain water does not run into the connectors.



Off Topic; I an installing a roof top tv antenna. Everything I read says to ground the antenna cable before it goes into the house. Problem is my ground rod is 50 feet away on the opposite side of the house. Seems like a poor idea to run a ground cable under the house for this safety feature.
Would it be okay to instal a separate ground rod at the antenna entrance. Or will this cause noise issues since the tv will be attached to a separate ground point. I suppose I good run a wire between the two ground rods to tie them together.
Very seldom any lightning here, never touches ground just cloud to cloud.
Bill D
 

steve-l

Titanium
Joined
Mar 2, 2012
Location
Geilenkirchen, Germany
I seriously doubt that you can get any noise problem by grounding the coax. Except, of course, during an actual lightning strike and then, you probably will be worrying about bigger things.

I would use the shortest route possible to run a heavy ground cable from the bottom of the mast to a ground rod. And let the mast extend a foot or so ABOVE the antenna. As for the coax, I doubt that any cautions that you can take will either protect the electronic circuit it is connected to or provide any additional safety to your person than the grounding provided by the TV/receiver it is connected to. If you really want to, ground or attach a spark gap device at the point where it enters the house and ground that to the same ground rod via the shortest path possible.

Lightning protection depends on providing a VERY LOW RESISTANCE path for it to take. Running a wire to the other side of the house is counter productive. Keep it SHORT and use heavy gauge wire.

Lightning is a very strong electrical impulse and once it gets into the coax, there is likely no stopping it as far as protecting the circuitry is concerned. Best bet is to provide a much lower resistance path down the mast and the ground rod. It probably will not save the electronics where only a few tens of Volts will be a disaster, but you and your family will be well protected by that low resistance path and the additional, low resistance path of the house wiring's safety ground through the chassis.

As for noise, you will never see it. Digital signals either work, or fail completely. It is called the waterfall effect: good until it fails and then it very quickly fails completely. Just keep the connections tight and put "rubber" boots or some silicone sealer over the outside connections to prevent corrosion. Also use drip loops so the rain water does not run into the connectors.

EPAIII,
Your comment is waay too simplistic. The word resistance does not apply because it is not just DC, you must use the term impedance because the effect you are describing is a product of AC and DC. You should also recognize that a straight wire of any length can be an open circuit depending on the frequency (think wavelength) of an impulse. This is why ground rod arrays are used with different length wires interconnecting them as it lowers the overall inductive reactance, broadening the effective bandwidth of the array. No matter how careful we are, we will never create a Zero OHM path to the equalization bus (local ground bus) in house. So this bus will always be at some potential relative to any other place anywhere, but whatever that potential is, it is yours and will always be your "0" Volt reference. Therefore, as long as all your stuff uses your equalization bus, you won't have any issues. One more thing, there is no such thing as Digital. We live in an analog world. Digital is simply a presentation of that world.
 

Scottl

Diamond
Joined
Nov 3, 2013
Location
Eastern Massachusetts, USA
Hmmm, where to begin?

First of all, simply grounding the coax vs input filtering can indeed result in noise problems.

As for the statement that "Lightning is a very strong electrical impulse and once it gets into the coax, there is likely no stopping it as far as protecting the circuitry is concerned" that may be true for a direct strike with enough power to blow chimneys etc. apart but most lightning induced spikes are from cloud-to-cloud bursts where strong electric fields get coupled into the cable and longer cable runs develop higher terminal voltages because the equation is based on volts per meter.

The good news is that although to us such strikes seem instantaneous and unstoppable it actually takes time for it to propagate along the cable and spark gaps and semiconductor over-voltage protection can work in combination to protect the equipment. I used to test industrial equipment for surge immunity using testers that simulated such lightning induced voltages. Spark gaps work, especially the gas filled ones which are much more repeatable than ones relying on atmosphere. Many times the equipment also had a secondary spark gap at the PCB terminal with an array of over-voltage protection devices. They work, although repeated surges can degrade the secondary gap and the semiconductors, which are a sacrificial part.

A supplier of commercial TV cable and antenna accessories should have quality devices that will do the job.

I seriously doubt that you can get any noise problem by grounding the coax. Except, of course, during an actual lightning strike and then, you probably will be worrying about bigger things.

I would use the shortest route possible to run a heavy ground cable from the bottom of the mast to a ground rod. And let the mast extend a foot or so ABOVE the antenna. As for the coax, I doubt that any cautions that you can take will either protect the electronic circuit it is connected to or provide any additional safety to your person than the grounding provided by the TV/receiver it is connected to. If you really want to, ground or attach a spark gap device at the point where it enters the house and ground that to the same ground rod via the shortest path possible.

Lightning protection depends on providing a VERY LOW RESISTANCE path for it to take. Running a wire to the other side of the house is counter productive. Keep it SHORT and use heavy gauge wire.

Lightning is a very strong electrical impulse and once it gets into the coax, there is likely no stopping it as far as protecting the circuitry is concerned. Best bet is to provide a much lower resistance path down the mast and the ground rod. It probably will not save the electronics where only a few tens of Volts will be a disaster, but you and your family will be well protected by that low resistance path and the additional, low resistance path of the house wiring's safety ground through the chassis.

As for noise, you will never see it. Digital signals either work, or fail completely. It is called the waterfall effect: good until it fails and then it very quickly fails completely. Just keep the connections tight and put "rubber" boots or some silicone sealer over the outside connections to prevent corrosion. Also use drip loops so the rain water does not run into the connectors.
 








 
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