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N2RJ
04-09-2007, 03:35 PM
I've been doing some research on grounds because I want to make sure I have an effective RF ground.

My shack and home office is on the ground floor, close to the front of the house. The entry point is the window, about 6ft above ground.

For now I drove an 8ft 5/8 ground rod into the ground. That is my ground at the shack entry point. I eventually plan to add a more elaborate grounding system, but this works for now.

I was reading about which wire to use to ground, and I read that using braid is "an old wives tale." (http://www.hamuniverse.com/grounding.html)

So I decided to make a shielded ground like they recommended, which is coax, shield to center at the ground side, and a .1uF capacitor on the station side.

Using this my noise level immediately went almost to zero on 20m. It was S3 to S5 previously. The few RF problems I've been having (hot radio and a bit of TVI when running high power) were gone completely. So I know my grounding did something good.

However, did I waste a piece of coax doing the shielded ground? What do you guys think?

What do you guys use for your RF ground?

Why did N8SA say that using braid is an old wives tale?

Oh, and to those not convinced that a ground isn't necessary, trust me it is. All of my RFI issues were gone with one fell swoop and the noise level went completely away.

VE2NSM
04-09-2007, 03:45 PM
I learned to never NEVER ground your station through the back of the radios, buss bar, ground braid through the window, ground rod, ect...

The ONLY way I ground my station is through the tower, at the base of the tower and at every guy wire, the station is floating with an isolation transformer from the house wiring and all the grounding is through the coaxes (which I never disconnect BTW).

I just hate when a lightning bolt comes into my shack looking for ground... but that's just me http://www.qrz.com/iB_html/non-cgi/emoticons/wink.gif

KN4DS
04-09-2007, 03:47 PM
Quote[/b] (AB2MH @ April 09 2007,10:35)]Oh, and to those not convinced that a ground isn't necessary, trust me it is. All of my RFI issues were gone with one fell swoop and the noise level went completely away.
I absolutely believe it... I've got an old FT-101EE that drifts on 75m when I transmit... unless I transmit into a dummy load, in which case it's as stable as a rock. It also doesn't drift on 40m, 20m or 15m...

An RF ground is in the near future for me.

N2RJ
04-09-2007, 03:49 PM
Quote[/b] (ve2nsm @ April 09 2007,10:45)]I learned to never NEVER ground your station through the back of the radios, buss bar, ground braid through the window, ground rod, ect...

The ONLY way I ground my station is through the tower, at the base of the tower and at every guy wire, the station is floating with an isolation transformer from the house wiring and all the grounding is through the coaxes (which I never disconnect BTW).

I just hate when a lightning bolt comes into my shack looking for ground... but that's just me http://www.qrz.com/iB_html/non-cgi/emoticons/wink.gif
That's why I said "for now" meaning "temporary."

I have no tower right now, only wire antennas.

KJ3N
04-09-2007, 03:53 PM
Quote[/b] (AB2MH @ April 09 2007,11:35)]Oh, and to those not convinced that a ground isn't necessary, trust me it is. All of my RFI issues were gone with one fell swoop and the noise level went completely away.
I'm glad it works for you.

However, my co-worker lives in the shadow of about 6 high-power AM and TV stations. We calculate that there is about 6 volts worth of RF currents in the soil. He has no worms anywhere in his yard, and neither do any of the neighbors.

Think he should put in a ground rod and hook to it? http://www.qrz.com/iB_html/non-cgi/emoticons/rock.gif

There is no one correct grounding situation.

N2RJ
04-09-2007, 03:56 PM
Quote[/b] (n3jja @ April 09 2007,10:53)]
Quote[/b] (AB2MH @ April 09 2007,11:35)]Oh, and to those not convinced that a ground isn't necessary, trust me it is. All of my RFI issues were gone with one fell swoop and the noise level went completely away.
I'm glad it works for you.

However, my co-worker lives in the shadow of about 6 high-power AM and TV stations. We calculate that there is about 6 volts worth of RF currents in the soil. He has no worms anywhere in his yard, and neither do any of the neighbors.

Think he should put in a ground rod and hook to it? http://www.qrz.com/iB_html/non-cgi/emoticons/rock.gif

There is no one correct grounding situation.
True, true.

However, personally I wouldn't want my shack in the shadow of any high power broadcasting or even cellular/communications equipment.

Just look at the problems S9SS had. While he's probably contacted every ham on earth, I pretty much doubt that was because he was in the shadow of the VOA site on Sao Tome!

AB0WR
04-09-2007, 03:58 PM
I keep reading that braids provides a series inductance which causes the shack end to actually be above RF ground.

Yet I've never seen an explanation of why this doesn't provide the same problem when used as part of a feedline. You would think it would present an open circuit to RF with that large of an inductance.

I use an inch wide, tinned, very heavy 10 foot piece of braid and I've never had a problem. I can certainly understand why a big piece of flat copper would be preferable but that just isn't reasonable for me to use.

I also use a copper buss bar out of the lighting system for an old movie theater as a single point ground window for all RF grounds in the shack. With copper prices today I shudder to think what it would cost new.

tim ab0wr

WB2WIK
04-09-2007, 04:04 PM
I've never found an earth ground, no matter how good, did anything to impact station performance for me -- including receive noise levels, RFI, or anything else.

Then again, running legal-limit power on eleven bands from home, I never had any RFI problems. I've always tried connecting and disconnecting a pretty good earth ground (8' copperclad ground rod driven into undisturbed soil immediately under my station gear, maybe 3'-4' away (since all the gear is on an outside wall of the hamshack, and I have access holes in the outside wall near floor level, right under the operating bench), connected via 4" wide solid copper flashing.

Zero difference in anything, here. Same went for my previous 13-14 hamshacks in other houses.

However, obviously it's not always like that for others.

The "braid" ground cable can work, but it's less effective than solid, smooth conductors because it has higher inductance per unit length for any given width. You can measure that, using an impedance bridge, an admittance bridge or an inductance bridge. I have, many times. No doubt about it, a solid, smooth conductor has lower inductance and thus lower impedance for RF.

The advantage of braided or woven conductors is that they're more flexible. That's pretty much their only advantage. When you need something that will take repeated flexing, like the ground bond cable between your engine and the engine hood of your car, braided is the way to go. For a "fixed" installation that won't be moved much, solid, smooth, wide conductors are the way to go. Copper flashing is about the best there is, followed by aluminum flashing. It takes a much wider braided conductor to have the equivalent low inductance.

WB2WIK/6

K0CMH
04-09-2007, 04:12 PM
Glad your grounding worked for you.

I hope this helps inform you about your grounding questions.

#1) When discussing RF grounding, surface area of the conductor is the important thing. I assume you know about the "sink effect" for conduction of RF current. It travels on the skin of the conductor, not much at all inside the conductor. That is why a 16 ga., 12 ga., etc. solid or stranded wire is a good electrical safety ground, but not a good RF ground. Many sources will say that the best RF conductor for grounding purposes is a flat piece of conductor (something like 2 inches wide), much like heavy foil. This provides thousands of times more surface area than a wire. The RF sees much less resistance and inductance from a flat type of conductor.

#2) A braided piece of conductor is simply a bunch of fine wires. Having many wires in theory would enhance conduction of RF currents verses a single wire, however, when compaired to a piece of flat stock, it is still pretty poor.

Also, I hope you are aware of the need to bond all ground rods in your building together. You will hear some state otherwise, and that this is also a wives tale, however, if you explore some of the web sites offered by companies that provide lightening protection, they will explain why this is very important. I had ran all my "grounds" to just one single ground rod (that being the electrical services ground rod). My house took a nearby lightening strike that fired three television sets, a cable modum and a cordless telephone. But not one piece of my ham equipment was effected at all, and it all was hooked up (but not turned on) when it hit. I had connected each and every piece of metal equipment to one common ground point, using a separate piece of wire for each. I then ran a large wire to the ground rod. This is an electrical safety ground and not an RF ground. If you use a separate ground rod for RF, I strongly suggest you find out if there are any other ground rods in your building's electrical system, and be sure they are all bonded together.

N2RJ
04-09-2007, 04:16 PM
Oh, absolutely. The NEC requires all grounds to be tied together. I ran an 8 gauge wire to the electrical ground at the meter, which is about 10 feet away.

VE2NSM
04-09-2007, 05:32 PM
Quote[/b] (AB2MH @ April 09 2007,11:49)]
Quote[/b] (ve2nsm @ April 09 2007,10:45)]I learned to never NEVER ground your station through the back of the radios, buss bar, ground braid through the window, ground rod, ect...

The ONLY way I ground my station is through the tower, at the base of the tower and at every guy wire, the station is floating with an isolation transformer from the house wiring and all the grounding is through the coaxes (which I never disconnect BTW).

I just hate when a lightning bolt comes into my shack looking for ground... but that's just me http://www.qrz.com/iB_html/non-cgi/emoticons/wink.gif
That's why I said "for now" meaning "temporary."

I have no tower right now, only wire antennas.
Yes, when there is no tower the matter is different http://www.qrz.com/iB_html/non-cgi/emoticons/tounge.gif

But, like somebody else stated, I have never experienced any difference between an RF ground or no FR ground.
The reason is that *maybe* I always used either beams or monoband half wave dipoles fed with 50 ohms coax and 1:1 baluns. I also used once an inverted L with radials for 160m, also fed with 50 ohms coax.

Since I never used multiband wire antennas fed with high impedance open line and "in shack" tuners, the RF ground issues were not as critical.

What do you think?

N2RJ
04-09-2007, 05:38 PM
Quote[/b] (ve2nsm @ April 09 2007,12:32)]
Quote[/b] (AB2MH @ April 09 2007,11:49)]
Quote[/b] (ve2nsm @ April 09 2007,10:45)]I learned to never NEVER ground your station through the back of the radios, buss bar, ground braid through the window, ground rod, ect...

The ONLY way I ground my station is through the tower, at the base of the tower and at every guy wire, the station is floating with an isolation transformer from the house wiring and all the grounding is through the coaxes (which I never disconnect BTW).

I just hate when a lightning bolt comes into my shack looking for ground... but that's just me http://www.qrz.com/iB_html/non-cgi/emoticons/wink.gif
That's why I said "for now" meaning "temporary."

I have no tower right now, only wire antennas.
Yes, when there is no tower the matter is different http://www.qrz.com/iB_html/non-cgi/emoticons/tounge.gif

But, like somebody else stated, I have never experienced any difference between an RF ground or no FR ground.
The reason is that *maybe* I always used either beams or monoband half wave dipoles fed with 50 ohms coax and 1:1 baluns. I also used once an inverted L with radials for 160m, also fed with 50 ohms coax.

Since I never used multiband wire antennas fed with high impedance open line and "in shack" tuners, the RF ground issues were not as critical.

What do you think?
That is true.

When I used coax fed antennas with baluns at the feedpoint, RF in the shack wasn't an issue.

K1VSK
04-09-2007, 06:16 PM
Case in point:
We have used various configurations of antennas and grounds on our boat which is in salt water - about the best "ground" you can get but I infer from all prior comments as well as the original question that we are mixing apples with oranges - ground vs. counterpoise.
One has only to look at the most effective boat systems to glean what will be useful on land. Grounding for safety is a moot point. Grounding for the efficacy of a counterpoise is the real issue and here a good system becomes clear in terms of what works best. As an example of the differential, one has only to listen to a receive signal with and without an effective counterpoise connection. The improvement when connected to an effective system is marked as well as with transmitted signal apparent radiated power.
Over the (many) years and many more antenna configurations onboard, the conventional wisdom among boaters using HF communications has proven true and used successfully at my many qths.
Virtually any antenna can benefit from solid copper foil interconnecting the antenna and station ground side to an effective counterpoise with the added benefit of reducing stray noise level significantly. Achieving a good conductor to ground (or salt water) counterpoise is more an issue of how much improvement one wants to achieve. In salt water, the hull/water connection is clearly a capacitance one by necessity. On land, it's obviously much easier but making the mistake of assuming a ground rod, regardless of whether it's at the shack or tower end, is all that's needed - typically, one ground rod does nothing more than give the installer a false sense of accomplishment unless your groundwater is very shallow or the ground extraordinarily conductive.
Time andspace preclude a thorough discussion of what makes a good system and it may be that other readers can provide references for a better review. Suffice it to say that it's apparent lots of folks could benefit from learning more about an effective "grounding system".

K4AVL
04-09-2007, 06:48 PM
My shack room is on the second floor about 30' off the ground, as I live on a steep hill. I haven't got all my equipment ironed out yet, so haven't been on the air, but I have 2 coax fed dipoles 50-60' away, fed out through the window here.
I also put a 10 gauge bare copper wire through the window, and it's bolted directly to the 8' deep driven house entrance ground rod on the ground by the electric meter, running down along the outside wooden siding of the house. So, basically, this adds as risk from lightning? and won't help me signal-wise if all my radio equipment chassis' are connected to it? Just wanted to clarify this.

N2RJ
04-09-2007, 07:18 PM
Quote[/b] (KI4TBW @ April 09 2007,13:48)]My shack room is on the second floor about 30' off the ground, as I live on a steep hill. I haven't got all my equipment ironed out yet, so haven't been on the air, but I have 2 coax fed dipoles 50-60' away, fed out through the window here.
I also put a 10 gauge bare copper wire through the window, and it's bolted directly to the 8' deep driven house entrance ground rod on the ground by the electric meter, running down along the outside wooden siding of the house. So, basically, this adds as risk from lightning? and won't help me signal-wise if all my radio equipment chassis' are connected to it? Just wanted to clarify this.
I don't think your lightning risk increases if all grounds are bonded together, as you have done.

If you have separate ground rods that are not connected, that is asking for trouble.

You also have a different problem - your ground wire is also an antenna, since you are on a second story.

K1VSK
04-09-2007, 07:43 PM
Too much mis-information...
The effect, if any, of a ground rod on the likelihood of a lightning strike is an art, not science. There are conflicting schools of thought and thus far, not one has emerged as the more accurate. It is for this very reason (of uncertainty) that boat manufacturer standards conflict on the advisability of grounding particularly on sailboats which are much more prone to lightning than any tower you could imagine. About the only point on which you will find agreement is that having all equipment at the same (ground) potential will minimize electrical shock. Anything resembling a declarative statement about what is best is pure conjecture.

VE2NSM
04-09-2007, 07:47 PM
Quote[/b] (AB2MH @ April 09 2007,15:18)]If you have separate ground rods that are not connected, that is asking for trouble.
This is something that I'm not convinced about, actually I am confused about what to do.

I am building my house right now and I am taking special care about my electrical panel grounding, also I will install the 60' tower on the roof of the house, with anchors installed prior to pouring the concrete of the roof. Obviously, the way the houses are made here, they are just a big mesh of rebar from top to bottom, so my tower will be bonded to this mesh wether I like it or not.

My confusion is about grounding the tower separately and hook up my station to this ground via the coaxes, or not grounding the tower at all....

The latter was the way I was setup at my last location, tower on the roof, three anchors through the roof border, obviously hitting rebars on the way, wham bam thank you mam... never had a lightning problem in 5 years.

N2RJ
04-09-2007, 07:56 PM
Quote[/b] (ve2nsm @ April 09 2007,14:47)]
Quote[/b] (AB2MH @ April 09 2007,15:18)]If you have separate ground rods that are not connected, that is asking for trouble.
This is something that I'm not convinced about, actually I am confused about what to do.

I am building my house right now and I am taking special care about my electrical panel grounding, also I will install the 60' tower on the roof of the house, with anchors installed prior to pouring the concrete of the roof. Obviously, the way the houses are made here, they are just a big mesh of rebar from top to bottom, so my tower will be bonded to this mesh wether I like it or not.

My confusion is about grounding the tower separately and hook up my station to this ground via the coaxes, or not grounding the tower at all....

The latter was the way I was setup at my last location, tower on the roof, three anchors through the roof border, obviously hitting rebars on the way, wham bam thank you mam... never had a lightning problem in 5 years.
Separate grounds are actually prohibited by the National Electrical Code here in the US. All grounds must be tied together.

I was also reading this (http://www.w8ji.com/station_ground.htm) for a bit of explanation and it seemed to make sense.

VE2NSM
04-09-2007, 09:02 PM
Quote[/b] ]The most common place lightning hits is on the power lines. Lightning surges follow the drop to the house entrance (D), where a small portion of the surge is diverted to the entrance ground ©. The largest portion flows through the house wiring to the station equipment and out to the antenna (A) and station ground (B).

Good grounds installed at A and B actually increase current flowing through the house wiring and radio equipment.

It does make a lot of sense, but it's exactly my point. I always have my station power ISOLATED from the rest of the house through an isolation transformer and I take good care of NOT having the third prong of any equipment connected to the rest of the house, but instead to the other ground through the coaxes and outside.

The logic behind this, is that my tower that extends 80' above the neighbourhood is kind of an attraction for lightning and I want to avoid as much as possible having an eventual surge reach the house wiring.

Maybe I'm wrong. If they say most of the time the surge enters through the utility line, which I can not deny either.

VE2NSM
04-09-2007, 09:04 PM
If I follow that theory, the best way would have to have the tower and shack Isolated from the natural ground path, leaving only the electrical panel ground rod.

And why would most of the current flow through the radio ground instead of the electrical ground? http://www.qrz.com/iB_html/non-cgi/emoticons/rock.gif

Some things don't add up.

N2RJ
04-10-2007, 12:58 AM
Quote[/b] (ve2nsm @ April 09 2007,16:02)]
Quote[/b] ]The most common place lightning hits is on the power lines. Lightning surges follow the drop to the house entrance (D), where a small portion of the surge is diverted to the entrance ground . The largest portion flows through the house wiring to the station equipment and out to the antenna (A) and station ground (B).

Good grounds installed at A and B actually increase current flowing through the house wiring and radio equipment.

It does make a lot of sense, but it's exactly my point. I always have my station power ISOLATED from the rest of the house through an isolation transformer and I take good care of NOT having the third prong of any equipment connected to the rest of the house, but instead to the other ground through the coaxes and outside.

The logic behind this, is that my tower that extends 80' above the neighbourhood is kind of an attraction for lightning and I want to avoid as much as possible having an eventual surge reach the house wiring.

Maybe I'm wrong. If they say most of the time the surge enters through the utility line, which I can not deny either.
If you are hit by lightning, a puny isolation transformer simply will not matter.

If lightning can jump the gap from the cloud to your tower, then what is preventing it from jumping the gap across your transformer, or even inducing a huge pulse in the primary from the secondary?

As for taking out the ground, you sir are a brave man.

Not only are you violating the electrical code, you're putting yourself at risk of electrocution.

VE2NSM
04-10-2007, 01:35 AM
Not violating any code because code there's not to begin with.
That's the way all the repeaters are on the mountains here. Tower grounded, radios isolated from line and grounded through the coaxes.
That setup is proven already since many years, I'm just trying to adapt it and possibly improve it.

As for the isolation transformer, true, it won't matter if it's THE ONLY PATH, but the point is exactly that, to provide a VERY good path, but outside the house, not in.

KA5PIU
04-10-2007, 02:09 AM
Hello.

I have been over this a few times to know the code.
http://ecmweb.com/mag/electric_basics_isolated_grounding/
So, one can do an Isolated Ground and meet all code requirements.
The second thing, yes, a transformer can isolate, but ye ol pole pigg does NOT do this.
If this were the case we would not have to worry about a hot chassis in an AC/DC radio.
Most transformers are primary hi-line to ground, secondary center tap to ground with 2 legs each, 120v to ground and 240v to each other.
Again, there is NO ground isolation from a distribution transformer.
In europe there is but one hot wire and a ground in most residence service.

VE2NSM
04-10-2007, 02:17 AM
I have a 4KVA isolation transformer, 220VAC in, 120 VAC out 40A. It's quite a boat anchor http://www.qrz.com/iB_html/non-cgi/emoticons/tounge.gif

I run my shack off it, but then again, no amplifiers of course, I'm a barefoot kind of guy.

KA0GKT
04-10-2007, 02:29 AM
In most soil conditions, one ground rod isn't a good ground. You need several ground rods seperated by twice the length (depth) of the rods and bonded together to begin to have a good ground in all but the best ground conductivity areas (salt water or salt marsh)

Since RF travels near the surface of a conductor (Skin Effect), the greater the surface area the lower the resistive component in the impedance of the ground. Multiple conductors which aren't insulated from each other act as one from the perspective of skin effect. Multiple conductors in a bundle and insulated from each other (like Litz wire which maximizes the surface area of the multi-conductor wire by using several flat conductors insulated from each other.) Practically, a strip of 16 ga 2" wide solid copper strap (in the copper business this is called copper strip) will be a better ground conductor than a copper braid of the same size.

73 DE KAGKT/7

--Steve

K9KJM
04-10-2007, 06:53 AM
First of all, The link you provide in your first post has the guy saying "Nothing can protect your equipment from a direct lightning strike" THAT tells me the guy is full of B.S.!!!!!!!! #
Nowadays, Properly installed tower systems DO NOT suffer damage from direct lightning strikes! #Think it over.
Cellphone towers, Police, Fire, Commercial radio and TV stations, Repeater towers for ham radio, etc etc. (And my own tall tower here on the hill where I live) ALL TAKE direct lightning strikes most every large storm, With NO #damage to equipment!
The different "types" of ground systems (RF, Lightning, Safety, etc) all have different requirements.
RF ground is best done with the flat copper strap, Out to a nice radial system of flat copper strap, Then running out to something like #10 solid copper wire (Thats what commercial AM radio stations use)
The REASON copper braid is not suggested is because of the oxidation that happens between the individual strands outdoors........ #That creates problems. So copper braid should only be used where it is really needed for flexibility, Like from a steel door frame to the steel door, etc. And then tinned copper braid is best to help minimize oxidation.
Ground rods do pretty close to zero for your RF grounding.
(But do help out your lightning and safety ground)

K1VSK
04-30-2007, 03:24 PM
Quote[/b] (k9kjm @ April 09 2007,23:53)]First of all, The link you provide in your first post has the guy saying "Nothing can protect your equipment from a direct lightning strike" THAT tells me the guy is full of B.S.!!!!!!!! #
Nowadays, Properly installed tower systems DO NOT suffer damage from direct lightning strikes! #Think it over.
Cellphone towers, Police, Fire, Commercial radio and TV stations, Repeater towers for ham radio, etc etc. (And my own tall tower here on the hill where I live) ALL TAKE direct lightning strikes most every large storm, With NO #damage to equipment!
The different "types" of ground systems (RF, Lightning, Safety, etc) all have different requirements.
RF ground is best done with the flat copper strap, Out to a nice radial system of flat copper strap, Then running out to something like #10 solid copper wire (Thats what commercial AM radio stations use)
The REASON copper braid is not suggested is because of the oxidation that happens between the individual strands outdoors........ #That creates problems. So copper braid should only be used where it is really needed for flexibility, Like from a steel door frame to the steel door, etc. And then tinned copper braid is best to help minimize oxidation.
Ground rods do pretty close to zero for your RF grounding.
(But do help out your lightning and safety ground)
I'd hold off on calling other folks' comments "BS". One of the local Boston stations was off air for 2 hrs the other day as a result of a strike destroying their equipment including what you'd consider to be a "properly installed tower sysrtem".
Anyone who makes absolute statements regarding grounding and it's effect on lightning is more likely the one who's opinons should be considered dubious

K9KJM
05-01-2007, 07:17 AM
While the only things in this world that are 100% are death and taxes, Radio towers and stations that have been properly protected simply no longer suffer outages like they did 30 or so years ago. #I suspect there was a flaw in the design of that stations protection system.

(And in fact, Many years ago lots of two way radio dealers did very little to protect stations from lightning.
(And in the 50's about all that was suggested was a single 8 foot rod with a #6 copper wire!) #
Adding extra grounding equipment to a bid would only make your bid higher so you lost the bid, PLUS the fact that the installation was not protected properly would mean you got to replace fried equipment from the lightning damage, For even MORE profit!)

Properly BONDING all ground rods (And all ground systems) together is most important. Using flat copper strap. (Commercial towers now use 4 (Four) 6 inch wide copper straps from the single point ground plate where coax enters the building to the ground system.)
(A source of flat copper strap can be upscale roofers...
Before copper prices took off they tossed scraps in the dumpster!)
Ground RODS usually do very little to add to a stations RF ground. (But do a lot for safety and lightning ground)

As WIK pointed out, If you have decent balanced antennas, You should have very little need for an extensive RF ground in your shack.
A system of ground radial wires for low HF (Like 160 meters) operation is a different story.

W4HAY
05-01-2007, 11:30 AM
Back to the original question: I use a copper strap along the back of the bench and flat braid (for flexibility) leading outside.

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