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Author Topic: 2nd-floor ground...is my proposed method a bad one?  (Read 2042 times)
KB1TXK
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« on: December 05, 2011, 05:54:30 AM »

I had to move the shack from the basement (humidity, constant odor of cat s--t no matter how much we keep up w/ it) to the second floor.  I have an 8' stake just under the window, connected to 4 more stakes 7' apart.  The electrical entrance is grounded to a stake at the other end of the run.

I'm getting one of those MFJ window-pass-thru boxes for the coax.  I intend to use copper strap to connect it to ground.  Rather than run 10' of strap, I intend to slip 10' of copper pipe over the end of the stake, crimp it, and run the ground strap to that

I'll drill small holes at the bottom end of the pipe to let rainwater run out.

Small diameter copper pipe isn't that expensive.  I figured this would be better at off-putting static build-up, etc than running 10' of strap and hoping it survives multiple winters, etc.

This is NOT lightning protection. I know that.  I'm just utilizing the single-point ground the MFJ window box provides to ground coax and equipment to a common area.

Anyways...any reason I shouldn't do this? Aesthetics don't matter.

Thanks!
« Last Edit: December 05, 2011, 05:57:03 AM by KB1TXK » Logged

KL0S
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« Reply #1 on: December 05, 2011, 06:16:13 AM »

I'm kinda in the same boat...at my last QTH I had a window box on the second floor with the copper plate the cable/rotator arrestors were mounted on connected to a 8' ground rod by a wide copper strap immediately below the window/box. We've moved and I have the same issue, BUT I'm having an electrician install a sub-panel here in the shack that will control the 20A service to the outlets for the radio/work benches [you know, in case I'm found doing the "funky chicken" and a lay person could see the emergency panel and shut off all the power quickly].  As the sub panel will be directly tied to the service ground is this sufficient ground for the shack?  The arrestors will still have to be tied to a ground and I wonder if that's sufficient?

Any advice may help both of us.

Thanks in advance!

73 - Dino KL0S
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M6GOM
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« Reply #2 on: December 05, 2011, 08:16:06 AM »

Why do you need to put this kind of ground in? Its what people use when they don't put in a proper RF ground at the antenna.

Surely you'd be better getting rid of static long before it got to the shack at, say, the ANTENNA? And if you're using dipoles or doublets or any other balanced antenna, you don't need this strap.

Ground lugs on equipment are put there for people who can't set up stations properly. I have never ever had RF in the shack, not ever. I use dipoles and verticals with good radial systems and pop a common mode choke on the co-ax at the antenna feedpoint for the verticals.
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KB1TXK
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« Reply #3 on: December 05, 2011, 08:19:59 AM »

Oh all the antennas are grounded at the antenna.  This would jsut make me feel better. Its a 'peice of mind' ground Wink
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WB6BYU
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« Reply #4 on: December 05, 2011, 08:21:56 AM »

The first questions always is, WHY ARE YOU INSTALLING A GROUND?

There are several possible reasons, but the requirements are quite different, for example, for
lightning protection, AC safety, or for your antenna to work against, and what works for one
reason may not be a good choice for the others. (At one point I think I listed 7 different
reasons one might use a ground in a ham station, but I often operate without any at all.)

So until you can explain the purpose of the ground you are trying to install, we can't tell
you whether it is a good method for accomplishing it.
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K2DC
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« Reply #5 on: December 05, 2011, 01:31:00 PM »

WB6BYU's post falls in the catagory of "Nuff Said".  You need to determine why you think you need a ground to determine how to best go about it.  My lightning and static bleed ground is a lightning rod at the top of the mast, with a 00 ground lead bonded to an 8' rod at the base of the tower.  My safety ground is all in the house wiring - all of my gear are on three-pronged plugs.  I have no RF ground.  There is nothing attached to the ground lugs on any of my equipment, rigs, tuner, amps - nothing.  Never had a problem. 

In fact if not done properly, separate grounds on the equipment can create more problems than they solve by establishing ground loops.  So ask youself why you think there's a problem and investigate the best method to attack that problem before you start.

73,

Don, K2DC
 
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KB9YNB
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« Reply #6 on: December 06, 2011, 06:42:23 AM »

Without getting into the "value" of installing such a ground,  I will simply comment:   Mechanically, your method doesn't sound like a good one.

By crimping the pipe to the "stake" (I assume a copper-clad ground rod?) you're allowing room for water and air to infiltrate, and eventually corrode this connection.

If you're dead-set on using pipe,  I would use a torch and solder the pipe to the stake.

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KB1GTX
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« Reply #7 on: December 06, 2011, 05:10:34 PM »

http://www.ebay.com/itm/New-ORECK-XL-AIRPB-Super-Air-Table-Top-Purifier-AIRPCB-Truman-Cell-Technology-/260872584943?pt=LH_DefaultDomain_0&hash=item3cbd37beef

One of these and a dehumidifier!
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K2DC
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« Reply #8 on: December 07, 2011, 04:11:41 AM »

I have no idea what the air purifier or dehumidifier have to do with needing an RF groung in the shack.  Probably no connection at all.  If you're concerned about RFI from either, a supplemental ground on the ham equipment will not help in any way.

If it helps you any, we have two dehumidifiers and two of the Oreck air purifiers in the house.  There is one of each within 8' of the shack.  The other dehumidifer and air purifier are within 20' of the shack.  One of the dehumidifiers and one of the air purifiers are in the finished part of the basement right outside the shack, and on the same power circuit as all my equipment.  No RF ground on my equipment here, and no problems.

73,

Don, K2DC
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K4SAV
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« Reply #9 on: December 07, 2011, 07:52:26 AM »

This is NOT lightning protection. I know that.  I'm just utilizing the single-point ground the MFJ window box provides to ground coax and equipment to a common area.

I can't determine if it works for lightning or not since most of the detail for that was missing.  It might work for lightning depending on how the antenna is grounded near the antenna base and the length of the run back to the AC electrical ground rod.  It might work for a redundant safety ground if you think you really need a redundant safety ground.  (Safety grounds usually only work for dc and 60 Hz.)

It won't work for RF ground, but that depends on your definition of RF ground.  I think the term "RF ground" is not used outside amateur radio and I have never seen a written definition in any book, or even a definition by another ham of "RF ground" or what they think it should do.  I gave one but that was only my opinion and it seems that within the general ham population there is no consensus of what it is.  The ARRL Antenna book doesn't define it either but implies that it is a low impedance path to earth.  I can only assume they mean low enough impedance to actually do something besides becoming a radiator.  That would make establishing an RF ground connection to your rig almost impossible for nearly all hams.

Jerry, K4SAV
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