ORIGINAL MESSAGE:

On Mon, 02 Jan 2006 00:17:00 +0000, Dan Andersson
wrote:

Forget about balun's and other widgetry!

Get a virtual earth! They are easy to build for all ham bands!

It's basically a phasing unit for the earth connection which can null the
voltage on the earth at the RF Rig!

If you don't want to build one, MFJ sells one!

Cheers

M0DFI


~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

They're great if you like your antenna two feet above ground.

The way you "null out the voltage" is by making that wire resonant and
resonant wires love to radiate. Nobody would intentionally install an
antenna below knee level, but that's what you're doing.

Busted any pileups lately? :-)

73, Bill W6WRT

Bill Turner wrote:

They're great if you like your antenna two feet above ground.

The way you "null out the voltage" is by making that wire resonant and
resonant wires love to radiate. Nobody would intentionally install an
antenna below knee level, but that's what you're doing.
. . .

I don't agree entirely with some of the recent short postings. And
making a wire resonant doesn't make it radiate any better or worse than
a non-resonant one. But if you have an unbalanced feedline (and by this
I don't mean a symmetrical feedline like ladder line, but one of any
construction with imbalanced currents) and consequential current from
your rig to ground, that conductive path to ground will radiate just
like an antenna -- any current flowing on a conductor causes radiation,
regardless of whether we consider it to be an "antenna", a "ground
wire", or a "transmission line". And as Bill points out, the location of
a ground wire isn't usually what you'd choose for an antenna. Other
consequential effects are that an unbalanced feedline has a net (common
mode) current and so it radiates, too. The feedline and ground wire are
also part of the antenna when receiving, so they'll be good at receiving
noise that's generated in the house or radiating from mains wiring. All
in all, it's not an ideal situation, although quite a number of people
manage to get away with it.

Roy Lewallen, W7EL

ORIGINAL MESSAGE:

On Sun, 01 Jan 2006 18:45:57 -0800, Roy Lewallen
wrote:


I don't agree entirely with some of the recent short postings. And
making a wire resonant doesn't make it radiate any better or worse than
a non-resonant one.

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

You are correct of course. I should have said a resonant antenna (or
ground wire) is easier to couple energy into, and in that sense, it
radiates better.

73, Bill W6WRT

Forget about balun's and other widgetry!

And replace it with snake oil? Why?

Get a virtual earth! They are easy to build for all ham bands!

He's probably fairly young , has his health, etc. The last
thing he needs is a "virtual earth" on the 2nd floor.

It's basically a phasing unit for the earth connection which can null the
voltage on the earth at the RF Rig!

It's basically a bandaid device to cure problems from using
poorly designed antenna systems. .

If you don't want to build one, MFJ sells one!

I don't doubt that. They sell about everything else...

Seriously, if someone is on a 2nd floor, or even a ground
floor, there is no need for rf grounding in the shack at all.
All he needs to do is run complete antennas and there
is *no* need for any rf grounding. Sure, he needs safety
grounding for some gear, but that is taken care of by a
grounded electrical cord. RF grounding should always
be under an antenna that requires it. Not at a shack,
unless the antenna is fed from the shack. And that is
a bad way to live in general. All he needs to do is run
any complete antenna, such as a coax fed dipole, or
ladder line fed dipole, or a vertical that has it's own rf
ground under it. Adding a shack ground to any of these
scenarios is a waste of time. It also usually causes
more problems, than it hopes to cure...
If he's feeding any of those antennas with coax, which
I recommend for ease of use in any location, a balun
is his best friend, not widgetry.
I'm on the ground floor, and I use no RF ground
in the shack. Have no need for one. Grounding has
enough "wives tales" , etc, attached to it, to add
more snake oil, or bandaid solutions.
Lightning grounding is a whole nother story, but it also
belongs outside, and not in the shack so doesn't really
apply to his case of being on a 2nd floor and worrying
about a rf ground.
MK

"Dan Andersson" wrote in message
...
jawod wrote:

After reading the archive regarding 2nd floor grounding, a couple of
questions.

Outside of sufficiently thick gauge wire and proper depth to grounding
rod. Are there any ELECTRICAL (nonRF) issues left to resolve for a 2nd
floor ground?

Several articles referred to long grounding lines being close to 1/4
wavelength as being a problem. Is this eliminated with balanced
feedline?

Thanks,

john


Forget about balun's and other widgetry!

Get a virtual earth! They are easy to build for all ham bands!

It's basically a phasing unit for the earth connection which can null the
voltage on the earth at the RF Rig!

If you don't want to build one, MFJ sells one!

Cheers

M0DFI

Ok Dan, How about a follow up and give us a link or a schematic to build
one?

west

"Bill Turner" wrote in message
...

ORIGINAL MESSAGE:

On Sun, 01 Jan 2006 20:10:08 GMT, "west"
wrote:


"Bill Turner" wrote in message
.. .

ORIGINAL MESSAGE:

On Sat, 31 Dec 2005 10:16:19 -0500, jawod wrote:

Several articles referred to long grounding lines being close to 1/4
wavelength as being a problem. Is this eliminated with balanced
feedline?

Thanks,

john


~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

No. You can not "ground" your station for RF, at least not in the
sense of running a wire to ground. Don't bother because it isn't
necessary anyway. You do need two kinds of ground, one for the AC
mains for safety, and one for lightning.

RF energy is expensive to generate. Don't waste it by running part of
it into a lossy "ground". Keep it up in the air where it belongs.
Baluns are your friend.

73, Bill W6WRT

Bill,

I like your answer but it leaves me to want a bit more. Would you mind
expanding on your 2 paragraphs? Thanks.

west
AF4GC



~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

OK.

1. Running a wire from your rig to ground will not do what you think
it will. Any wire is a significant portion of a wavelength at HF and
may be many wavelengths at VHF and UHF. On ten meters, for example,
eight feet is almost exactly 1/4 wavelegth. If you recall your basic
transmission line theory, whatever condition is present at one end of
a 1/4 wave line has just the opposite at the other end. If you really
do have a good ground connection at the grounded end of the wire, the
other is an open circuit. Not very effective for grounding, is it?

The effect becomes less as you lower the frequency, but never
completely disappears. It is possible to tune out this effect with a
suitable coil and capacitor combination, but it really isn't needed
anyway. MFJ makes a "ground tuner" or whatever they call it, and I
suppose it does work, but think about this: If getting a good RF
ground actually improves your signal, you have a SERIOUS problem in
your antenna. More on this in the next paragraph.

2. RF does no good flowing through the earth. None at all. Dirt is a
poor conductor at any ham frequency and you should do your best to
keep your RF out of it. I suspect the idea that "ground" helps your
signal came from the very early days of radio when frequencies were
very low and wavelenghts were very long... miles long in fact. At
those frequencies there are two factors which might make use of ground
desireable: The earth is much more conductive at very low frequencies,
and miles of wire for an antenna is not easily done. Under those
circumstances, working a long wire against ground might actually be a
good idea. None of that applies to ham frequencies, of course. At ham
frequencies, RF works best when it's up in the air, all of it. Not in
the ground, not in your shack, up in the air.

Keep that in mind and you can't go wrong.

73, Bill W6WRT

That makes a lot of sense, Bill. It takes talent to take a rather technical
concept and put it into an easy to understand explanation. This post is
going in my Ham archive. Thanks again.

Cordially,
west
AF4GC

There are grounds and there are are grounds.

Lightning ground
House wiring safety ground
Antenna counterpoise (ground)
Ham shack common RF bus ground

If you live in an apartment building or if you use soundcard modes you
will soon find out that using the building's electrical safety ground
as your antenna's counterpoise is a bad thing.

Dont try to use an endfed wire antenna in an apartment.
You will be unhappy if you try to use your TV and soundcard speakers as
your antenna counterpoise.

I came to the conclusion that balanced antennas are the answer.

Put up a dipole or, better yet, a loop antenna.
Balanced antennas have their "ground" as part of the antenna itself.

I personally have never used a balun at the antenna but have used
choke baluns near the rig and have used 4:1 baluns at the tuner.
I often use an antenna tuner and ladder line so am not so sure that a
balun at the antenna is a good thing under those conditions.

I have experimented with "artificial grounds"
They are just a series L-C circuit that you insert between your
station common RF bus and your counterpoise system.
Series LC circuits act like a short when tuned so the idea is that
when your station counterpoise system is tuned with the series
LC circuit, your station bussbar ground will have the highest current
path to counterpoise system ground

You can make an RF current meter with a diode a toroid
a little magnet wire and a volt meter.

MFJ artificial grounds or tuned counterpoise tuners have you
tune for max current through the series LC circuit.

I have found that max current through the series LC circuit is not
always the best setting for getting minimum rf in the shack. I
use my soundcard speaker amp as my canary - tune the
counterpoise for least audio out of the speakers.

KL7R

PS, I live in a rain forest. I dont know a thing about lightning
grounds.

"kl7r" wrote
Dont try to use an endfed wire antenna in an apartment.

========================================

If the domestic plumbing system, hot and cold pipes, central heating
system and mains wiring are connected together, then the impedance to
true ground, as a whole, will be very low. The RF potential difference
between 'ground' and true ground at the lower HF frequencies will be
small.

In principle it could be measured - IF you could find a real ground.

The actual distance in wavelengths between 'ground' and true ground,
wherever that may be, is indeterminate and inconsequential.

In the extreme case the elevated ground system can be considered as a
sort of Faraday cage with no more than normal interference between the
electrical equipments in the vicinity.

By not using low-feedpoint-impedance anrtennas, such as exactly
1/4-wavelength or 3/4-wavelength in length, things can very often
continue as normal. It is, in any case, undesirable to use very low
impedance antennas even in good ground circumstances.

And antennas crudely 1/2-wavelength in length work just as well with
either good or very poor ground systems.

Appartment and flat dwellers should not be discouraged from simple
endfed antennas. In all probability they will be successful. Very
often they are unable to erect anything else.

My own experience extends from successful working with end-fed wires
from bedrooms to a 13th storey in an appartment block. The appartment
block antenna was a 0.3 wavelength sloping wire on the 160m band, open
circuit at the bottom end fed at the top.

Ground was an aligator-clip connection to the nearest hot water
radiator pipe in the domestic central heating system. But I could just
have well used the cold water pipe to the flush-tank in the toilet had
it been nearer.

Appartment dwellers - carry on as normal!
----
Reg, G4FGQ.