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Author Topic: Grounding for 2nd floor station  (Read 1797 times)
KE2KB
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Posts: 127




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« on: February 20, 2013, 12:37:05 PM »

Hi;
I have a Ringo Ranger ARX-2B (without the radials) mounted at the peak of the roof using a pair of wall-mounts.
I have a 6ft length of RG8 coming down from the antenna to an ICE #302 lightning arrestor, then a 50ft length of LMR400 running from there down to the radio on the 2nd floor of the house. The coax runs into the attic, under the floor, and down the closet wall into my shack.

The mast and the ICE are grounded using a clamp and a 40ft length of #4 THHN wire to the ground rod at the electrical service.

From what I have been reading, on both the ICE website, and several others, I should have the ICE arrestor located much closer to the ground rod.
I can do that, but then I need to run another 40ft length of LMR400 back up to my shack from the ICE.
Do I now need another ground at the radio?
The radio I am using on 2m is a Yaesu/Vertex VX-150 HT, so there is no need for an equipment ground for electrical purposes.

Any suggestions?

Thanks

KE2KB
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KF6ABU
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Posts: 351




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« Reply #1 on: February 20, 2013, 01:16:56 PM »

Ideally, the coax would run down to the service panel, and the lightning arrestor would be mounted to that. Then, then coax would run up to your shack. I dont think I would even bother with a all that for a 2m antenna, i'd just run the coax to my shack.
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KE2KB
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Posts: 127




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« Reply #2 on: February 20, 2013, 01:39:45 PM »

Ideally, the coax would run down to the service panel, and the lightning arrestor would be mounted to that. Then, then coax would run up to your shack. I dont think I would even bother with a all that for a 2m antenna, i'd just run the coax to my shack.
Yea; That's what I am kind of thinking now. For only 2m and not more than 5W, there shouldn't be an issue with RFI with the install I have now. I'd be wasting my time and money trying to make improvements. And it all wouldn't help the intermod problems anyway.

KE2KB
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KF6ABU
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Posts: 351




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« Reply #3 on: February 20, 2013, 05:05:56 PM »

Choking on the coax at the feed point, and radials would help with your RFI, or placing it further from the object experiencing problems.

Your coax is the other half of your antenna, currently.
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WB6BYU
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Posts: 13230




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« Reply #4 on: February 20, 2013, 06:49:49 PM »

First of all, you have to decide WHY you are grounding your antenna.
There are several different types of ground that serve different
purposes:  what might be a good ground for one reason often is
a poor one for other purposes.

For a lightning ground you want to run the coax down to
an arrestor mounted on a ground rod that is tied to the house
electrical ground with big wire, then run the coax from there to
the station.  You want to minimize the amount of current that may
flow along any wiring into the house on either the inside or outside
of the coax.

The radials provide a sufficient RF ground for the antenna.
Without them you will have common mode currents flowing on the
outside of the coax that will affect your radiation pattern (usually by
raising the angle of maximum radiation, which decreases signal
strengths at the horizon.)  In fact, Cushcraft added the radials to the
original Ranger after AEA marketed their Isopole, and pointed out how
it had better decoupling and an improved pattern (or at least more
reliable, as it wasn't dependent on feedline lengths, etc.)  This also
means anything you do to your coax routing, including adding ground
wires, can affect the antenna tuning and signal strengths.

For an RF ground in the shack, as is often recommended
to reduce RFI, it probably won't do you any good, since you are too
many wavelengths away from the ground to start with.  So that one
you don't have to worry about.
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KE2KB
Member

Posts: 127




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« Reply #5 on: February 20, 2013, 07:26:12 PM »

First of all, you have to decide WHY you are grounding your antenna.
There are several different types of ground that serve different
purposes:  what might be a good ground for one reason often is
a poor one for other purposes.

For a lightning ground you want to run the coax down to
an arrestor mounted on a ground rod that is tied to the house
electrical ground with big wire, then run the coax from there to
the station.  You want to minimize the amount of current that may
flow along any wiring into the house on either the inside or outside
of the coax.

The radials provide a sufficient RF ground for the antenna.
Without them you will have common mode currents flowing on the
outside of the coax that will affect your radiation pattern (usually by
raising the angle of maximum radiation, which decreases signal
strengths at the horizon.)  In fact, Cushcraft added the radials to the
original Ranger after AEA marketed their Isopole, and pointed out how
it had better decoupling and an improved pattern (or at least more
reliable, as it wasn't dependent on feedline lengths, etc.)  This also
means anything you do to your coax routing, including adding ground
wires, can affect the antenna tuning and signal strengths.

For an RF ground in the shack, as is often recommended
to reduce RFI, it probably won't do you any good, since you are too
many wavelengths away from the ground to start with.  So that one
you don't have to worry about.
OK. So the reason for grounding is lightning protection. The rig (VX-150 HT) doesn't need grounding.
I accept your argument on grounding at the electrical service ground rod.
So the #4 wire should run from the mast to the ground rod, and the coax should run uninterrupted from the antenna to the ground rod, where I will install the ICE lightning arrestor, which will also be bonded to the same ground rod.
Next, I run another length of LMR400 from the arrestor to the rig. Even though the radio is far from the ground rod, I don't think it will be an issue, since it's only 2m and 5W max.

As for the radials; it wouldn't make any sense to me to re-install them if they are going to hang below the eave, and be touching the aluminum siding on the eave. They would be detuned, and worthless.
If I could get the antenna up another 5-6ft so the radials will clear the eave and the roof, I would. But as I said, I can only access the antenna from the attic window; not from outside the house. That said, sometime between now and spring, I am going to look into that. I would have to purchase a new set of radials, as the originals are broken. Truthfully, I would like to replace the whole antenna. This Ringo Ranger ARX-2B is only a shadow of what my old ARX-2 was 30 years ago. It's very flimsy.
But honestly, my biggest use for this antenna is receiving on the railroad freqs (160-161.5Mhz). When I'm actually on the air on 2m, I am usually mobile in my car with a Larson mag mount or on foot with a whip on the HT.

KE2KB
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W5WSS
Member

Posts: 1723




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« Reply #6 on: February 21, 2013, 09:48:43 AM »

Some thoughts ,I would make the Earthing rod located next to the mains panel the better path to earthing for lightning protection as a system. Including the better path to ground even than the center conductor within the feed line to your ham station.

OR consider rerouting one wire, wiring to an outside rod located at the underneath the antenna base from the antenna to that rod leaving the mains panel and rod for a different station connection.

On one hand
This system then serves as the primary antenna system earthing with the intention of preventing voltage rise to discharge level from occurring in the first place and best because the earthing rod is located outdoors. Adding an in line coaxial arrest or for the purpose of center conductor protection is a good practice when located in such a place as to not or to a lessor extent sacrifice station field strengths due to extreme coaxial attenuation even when in a matched state. As could be at vhf and above if the redirected coaxial feed line travels all the way out of the way relative to a direct run for the purpose of placing the arrest or there. The added coaxial length should be evaluated for station performance and a more enlightened decision on whether one wants to sacrifice some station performance for center conductor lightning protection.
On the other hand,

The mains can be the station dc safety ground. using a large proper size wire to the mains panel earthing rod.

Lightning protection The antenna system can be an integral part since in your case the antenna is elevated presents an umbrella of protection around the near area serving as either a best path when rises above discharge level or preventing the rise in the first place either is best done outside and away from the equipment.

When the antenna system earthing is done properly outside and earthed at a location directly below the antenna base.
The arrest or can then be located anywhere between the antenna base and the point at which the feed line routing goes in a different direction and from there an earthing wire to the earthing rod directly below the antenna base.

This would accomplish the task and satisfy antenna redirect lightning protection and minimize the coaxial antenna feed line length.

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KE2KB
Member

Posts: 127




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« Reply #7 on: February 21, 2013, 02:14:10 PM »

Some thoughts ,I would make the Earthing rod located next to the mains panel the better path to earthing for lightning protection as a system. Including the better path to ground even than the center conductor within the feed line to your ham station.

OR consider rerouting one wire, wiring to an outside rod located at the underneath the antenna base from the antenna to that rod leaving the mains panel and rod for a different station connection.

On one hand
This system then serves as the primary antenna system earthing with the intention of preventing voltage rise to discharge level from occurring in the first place and best because the earthing rod is located outdoors. Adding an in line coaxial arrest or for the purpose of center conductor protection is a good practice when located in such a place as to not or to a lessor extent sacrifice station field strengths due to extreme coaxial attenuation even when in a matched state. As could be at vhf and above if the redirected coaxial feed line travels all the way out of the way relative to a direct run for the purpose of placing the arrest or there. The added coaxial length should be evaluated for station performance and a more enlightened decision on whether one wants to sacrifice some station performance for center conductor lightning protection.
On the other hand,

The mains can be the station dc safety ground. using a large proper size wire to the mains panel earthing rod.

Lightning protection The antenna system can be an integral part since in your case the antenna is elevated presents an umbrella of protection around the near area serving as either a best path when rises above discharge level or preventing the rise in the first place either is best done outside and away from the equipment.

When the antenna system earthing is done properly outside and earthed at a location directly below the antenna base.
The arrest or can then be located anywhere between the antenna base and the point at which the feed line routing goes in a different direction and from there an earthing wire to the earthing rod directly below the antenna base.

This would accomplish the task and satisfy antenna redirect lightning protection and minimize the coaxial antenna feed line length.


My current config has the arrestor located on the mast, just before the coax enters the house. That seems like a reasonable location, but I have been reading about this for the past few days, and have come to the understanding that the arrestor should be located closer to the ground, and thus the electrical system ground electrode, keeping the run from the arrestor to the ground electrode as short as possible.
I think I can see the point with that thinking. If the arrestor is located way up on the mast, with 40ft #4 copper conductor from the mast and the arrestor to the ground electrode, this can present a high impedance during a lightning event, since lightning is a spike rather than a gradual rise of current as our AC power lines are.
This situation would create a voltage along the grounding conductor, and thus a voltage would be present at the point where the coax enters the building, causing the coax to carry current into the building.
If, on the other hand, the arrestor is located down at the grounding electrode, and the coax enters the building immediately forward of the arrestor, any voltage that appears on the coax or grounding conductor from the mast/antenna would reach the ground before entering the house. The voltage drop between the grounding point (at the arrestor) and the ground electrode would be small, as the length of wire is now only a few inches.
Because the voltage between the arrestor and the ground electrode is now very small, the coax leading back to the radio from the arrestor will never carry a high voltage.

I don't think that adding another 40ft LMR400 between the arrestor and the radio is going to hurt performance noticeably. If anything, it will attenuate signals slightly, and result in less front-end overload in the HT, and thus less interference.

As I am trying to create as safe a system (in regards to lightning) as is practical, I think this change is worthwhile.

KE2KB
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N6AJR
Member

Posts: 9906




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« Reply #8 on: February 22, 2013, 08:53:45 AM »

I so agree.  I would run a straight rg 8 or lmr 400 type of coax  directly from the radio and to the antenna. 2 meter ringo is not a great lightning rod.  I think there is a well grounded street light or something much higher  near by to act as a  lightning attractor.  I would not worry about it.  I have several verts around the house and a 40 foot tower, and they are only grounded by their coax. so far no problems.
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W5WSS
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Posts: 1723




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« Reply #9 on: February 22, 2013, 09:09:35 AM »

Right on, either way would be good to excellent.

I would always strive to install the lightning arrestor closest to the Earthing rod and then route the antenna feed line from the arrestor to the equipment.

Whichever route that allows the least amount of additional loss within the coaxial antenna line.
Excessively long antenna feed line runs  at vhf and up should be evaluated.

That is not to say your run is excessively long and perhaps is perfectly acceptable.

You are thinking in the right direction

73
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W5WSS
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Posts: 1723




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« Reply #10 on: February 25, 2013, 06:45:09 AM »

However, the rise to discharge level Can be controlled with Lightning arrestor hardware. I am referring to the rise not the discharge stroke.

The point at which a rise reaches a level of stroke can be prevented when a lightning rod or better yet a ball of sharp points looks like a Porcupine is above the entire antenna compliment working to provide a path to a earthing rod.

That is done out at the antenna site

This is best accomplished when the lightning rod/ hardware to the earthing rod path is made to be the absolute least Resistance path to earth relative to the station equipment and immediate area near the station including the center conductor path.

Providing this best path out below your elevated pointy vertical is wise Because it works to prevent the rise upwards to discharge levels Installing the center conductor Arrestor is fine.

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LA9XSA
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Posts: 376




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« Reply #11 on: February 27, 2013, 06:35:46 PM »

The point at which a rise reaches a level of stroke can be prevented when a lightning rod or better yet a ball of sharp points looks like a Porcupine is above the entire antenna compliment working to provide a path to a earthing rod.
Just note that air terminals with spikes, or other types of "early streamer emission" techniques don't seem to have any actual evidence for working better than a regular air terminal, with the possible exception of GC strikes from the tallest of broadcast towers, and that exception is probably because there is just insufficient data.
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W5WSS
Member

Posts: 1723




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« Reply #12 on: February 28, 2013, 06:09:29 AM »

And so goes the debate.

There is plenty of evidence.

Put the point/s up above the antennas and use a large conductor to a series of earthing rods below the antenna.

73
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