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Author Topic: Good ground, top floor  (Read 286 times)
W8RJB
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Posts: 49




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« on: December 03, 2004, 05:24:32 AM »

What would be a good ground connection if I am on the top floor of the house for my new radio (FT 7800R)


73,
Ray
KD8AQO
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K1CJS
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Posts: 6061




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« Reply #1 on: December 03, 2004, 06:22:38 AM »

How far is the top floor of your house from ground level (earth ground)?  If the distance is too great, the answer may be no ground, depending on the antenna itself.  One thing is for sure, don't use the cover plate screw on the electrical outlet--thats just asking for trouble.
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KZ1X
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« Reply #2 on: December 03, 2004, 06:45:22 AM »

Why do you need a "ground" for a VHF radio?

You *might* want to have a safety ground for the ANTENNA or its support.  

That would be a grounding wire and ground rod, installed outide the house.  You might also wish to protect your coax, too, although it would be fairly ineffective if the protection wasn't at earth potential, which would mean you'd have to run your coax all the way to and from the ground rod ...
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W8RJB
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« Reply #3 on: December 03, 2004, 07:10:36 AM »

"Why do you need a "ground" for a VHF radio? "

Ahh ok. I think I need to go back and review some parts in my study guide. I am starting to forget. It's ok though, I always have the guide to look back at.

Thanks alot!

73,
KD8AQO
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WA6BFH
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« Reply #4 on: December 03, 2004, 12:01:25 PM »

KD8AGQ, Take a look at my article, "Why You Should Just About NEVER Install an RF Ground". It is both Toung in Cheek, and (in good contrast with the chap that asked why you want to ground a VHF radio) it is both somewhat serious and ACCURATE! There is also a link to the first detailed article I wrote on this subject several years ago.

You can find this article at the below URL:

www.geocities.com/SiliconValley/2775/whygrnd0.html
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KB4EMF
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Posts: 387




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« Reply #5 on: December 03, 2004, 12:28:42 PM »

Good RF ground is sort of an oxymoron....  especially for Amateur installations.  You could use a counterpoise, but I really don't see a need for one, especially for VHF/UHF.  If you are getting such a big amount of RF coming back through your coax, having a ground won't solve your problem.  Proper antenna tuning and feed-line cabling will.

Safety, ground, maybe, but then again, your radio is fed by a power-supply generated 12 volts.  You might want to ground the p/s instead.

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X-WB1AUW
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Posts: 559




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« Reply #6 on: December 03, 2004, 01:47:32 PM »

This is a VERY common question on eHam.  Hardly a month goes by without someone asking how they should ground their rig.

So don't feel bad about asking a common question.

When I got my first new rig, an FT101EX, the manual said to install a ground.  I ran a small diamteter wire through the drain hole in the storm window, from the second story, to a rusted 4 foot ground rod--very BAD set up!  Picked of TONS of RF from the 80/40 inverted Vee that that was strung from one side of the house to the other.

Have FUN
73
bob
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WB2WIK
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Posts: 20666




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« Reply #7 on: December 03, 2004, 03:56:30 PM »

I can't find any reason to ground anything, either.

In 39-going on-40 years of ham radio operations from dozens of stations, including 15 of my own home stations, plus lots of portable ones, and many "other people's" contest stations, I've yet to actually install a station ground for any reason.

Of course, one of my portable mountaintop operations found us in the center of a huge lightning storm.  I'm not sure a ground would have helped, but discretion was the better part of valor that afternoon and we pulled all plugs, closed up the tents and ran like hell for cover inside a building.  We wouldn't have stayed on the air that day with the best ground system in the world.

An "RF ground" for VHF-UHF is an oxymoron.  Unless your rig's laying on the ground outside, you'll never achieve one.  As has been pointed out, your rig doesn't have any connection to the AC mains at all, so any "safety ground" should be on the power supply, not your radio.

If you're in a lightning prone area, arrange a way to completely disconnect everything *outside* the house when a storm approaches.  A ground wire doesn't do anything to save your gear.

WB2WIK/6
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AA4PB
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Posts: 13032




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« Reply #8 on: December 03, 2004, 07:32:18 PM »

While you don't need an RF ground, you do need a lightning protection ground if your antenna is mounted on a tower or a mast on the roof. The tower or mast should be grounded to a ground rod via a heavy ground wire that runs outside the house. The shield of the coax should be grounded just before it enters the house. The National Electric Code requires it and in spite of what you may read on some of these forums there probably isn't a commercial antenna installer anywhere that would install an antenna without a lightning ground. A properly installed lightning ground *will* help to protect your rig and your house against lightning. Most lightning damage is not caused by a direct hit, but rather energy induced by lightning striking a tree or something else nearby. Take a look at the Polyphaser web site for details.
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W8JI
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Posts: 9296


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« Reply #9 on: December 04, 2004, 01:48:13 AM »

A rational level-headed person would probably NEVER trust a personal opinion or a non-peer reviewed article for critical safety information. They would go to reliable engineering sites, national electrical code sites, and similar peer reviewed places for information.

Factually, there are many more situations where you SHOULD have a good  ground on your station equipment then the rare situation where you can just ignore grounding because a particular person "hasn't been killed yet".

The idea of an RF ground on station equipment largely comes from people with screwed up equipment, antenna installations or antenna designs, but a **low frequency safety ground** is actually a VERY good idea.

Most amateur gear is NOT UL/CSA approved, and it almost always connects outside to a large metallic system that provides a conduit to lightning or power line or power supply malfunctions.

While a good RF ground on equipment is a patch for equipment or installation errors or flaws, only a fool would tell people to never ground a station with external antennas and cable. Safety grounds are required much more often than not.

73, Tom
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