"Richard Clark" wrote in message
...
On Sun, 12 Nov 2006 15:14:49 -0000, "Dave" wrote:

but rf doesn't flow 'into the earth'.

Hi Dave,

That statement is contradiction to the following:

'ground radials' ... are ... 'sucking' rf out of the ground.

It necessarily follows that RF does flow "into" the earth by your own
admission of it coming out (by whatever means).

in context of the message i was replying to the writer implied that rf
flowed 'into' the earth and that was the end of it, more correctly it could
be said that rf flows 'through' the earth, but it doesn't dissappear 'into'
the earth.


the 'ground' connection
to a radio feeding a dipole is actually returning current from the ground
back to the feedpoint via the outside of the coax shield...

Very true. However, the ellipsis (...) elongates a 25 word statement
into an 118 word run-on sentence:

i have been told before that i have very long trains of thought, usually i
am just trying to be descriptive enough for someone else to follow along...
and i just like ellipsis.


that is why you
can get high voltages at the radio end of the cable, if too much current
is
coupled from the antenna onto other conductors connected to 'ground' they
will feed current back through the radio 'ground' and out the shield of
the
feedline to get to the feedpoint, and if you happen to be too close to the
antenna or some other object that couples the rf to you then you get
burned
when the rf from you flows back to the radio when you touch something that
is 'grounded'.

If I try to parse the intent of this, it becomes a string of
assertions held in suspension until the summary that ties them
together. That never happens. The conclusion:
then you get burned
when the rf from you flows back to the radio when you touch something that
is 'grounded'.
bears no relation to the matter of currents in the earth - except as a
consequence to rather perverse conditions.

it relates to the common assumption that the radio case, coax shield, and
other items connected to a common 'ground' are at 'rf ground'. ignoring the
'earth', there is also the common misconception that things tied together to
the often discussed 'single point ground' are all 'grounded'... something
that is not necesssarily true when dealing with rf.

On Sun, 12 Nov 2006 19:25:38 -0000, "Dave" wrote:

in context of the message i was replying to the writer implied that rf
flowed 'into' the earth and that was the end of it, more correctly it could
be said that rf flows 'through' the earth, but it doesn't dissappear 'into'
the earth.

Hi Dave,

True, but knowing Bill, I doubt his description was meant to be so
literal as to having current disappear into the earth.

In the sense of RF ground, already described by me earlier, ground is
a pool of infinite charge and as such current into it does disappear.
Otherwise, it would perturb and become less than a ground, its
potential would elevate and that elevation would be in reference to
some other ground.

This is a true picture of the reality of ground as such perturbation
does just this, and is evidenced by local variations of potential to
other "grounds." However, this reduces the discussion to one of
infinite regression and over-qualifies an answer to the primary
question.

i have been told before that i have very long trains of thought, usually i
am just trying to be descriptive enough for someone else to follow along...
and i just like ellipsis.

Up to the ellipsis was fine. The better part of writing is what you
leave behind after you trim off the fat.

it relates to the common assumption that the radio case, coax shield, and
other items connected to a common 'ground' are at 'rf ground'. ignoring the
'earth', there is also the common misconception that things tied together to
the often discussed 'single point ground' are all 'grounded'... something
that is not necesssarily true when dealing with rf.

I can follow the argument for concern, but you really don't offer any
context. There are far more examples of grounding working than not;
and your brush has tarred them all equally.

There is the practical answer to the question of RF ground, and there
is the literal answer (or academic, if you prefer). The practical
answer might have the user elevated hundreds of volts above academic
RF ground. That user might never perceive it in any way because the
user may have contrived to build a virtual ground that satisfies all
the requirements for operating without suffering themselves or any one
else.

73's
Richard Clark, KB7QHC

In article ,
Richard Clark wrote:

On Sun, 12 Nov 2006 15:14:49 -0000, "Dave" wrote:

but rf doesn't flow 'into the earth'.

Hi Dave,

That statement is contradiction to the following:

'ground radials' ... are ... 'sucking' rf out of the ground.

It necessarily follows that RF does flow "into" the earth by your own
admission of it coming out (by whatever means).

the 'ground' connection
to a radio feeding a dipole is actually returning current from the ground
back to the feedpoint via the outside of the coax shield...

Very true. However, the ellipsis (...) elongates a 25 word statement
into an 118 word run-on sentence:

that is why you
can get high voltages at the radio end of the cable, if too much current is
coupled from the antenna onto other conductors connected to 'ground' they
will feed current back through the radio 'ground' and out the shield of the
feedline to get to the feedpoint, and if you happen to be too close to the
antenna or some other object that couples the rf to you then you get burned
when the rf from you flows back to the radio when you touch something that
is 'grounded'.

If I try to parse the intent of this, it becomes a string of
assertions held in suspension until the summary that ties them
together. That never happens. The conclusion:
then you get burned
when the rf from you flows back to the radio when you touch something that
is 'grounded'.
bears no relation to the matter of currents in the earth - except as a
consequence to rather perverse conditions.

73's
Richard Clark, KB7QHC

In other words...... the guy is so full of ****, his eyes are brown.....

ORIGINAL MESSAGE:

On Sun, 12 Nov 2006 15:14:49 -0000, "Dave" wrote:


but rf doesn't flow 'into the earth'

------------ REPLY FOLLOWS ------------

Beware of making broad statements that are supposed to be true in all
cases. The one above is not.

Bill, W6WRT

In article ,
Bill Turner wrote:

ORIGINAL MESSAGE:

On Sun, 12 Nov 2006 15:14:49 -0000, "Dave" wrote:


but rf doesn't flow 'into the earth'

------------ REPLY FOLLOWS ------------

Beware of making broad statements that are supposed to be true in all
cases. The one above is not.

Bill, W6WRT

One statement that IS True, and has been around "Forever":

Ground is not Ground, the World Around........


Me and RF Ground, is not Ground Ground........

Me wrote:
In article ,
Bill Turner wrote:

ORIGINAL MESSAGE:

On Sun, 12 Nov 2006 15:14:49 -0000, "Dave" wrote:


but rf doesn't flow 'into the earth'
------------ REPLY FOLLOWS ------------

Beware of making broad statements that are supposed to be true in all
cases. The one above is not.

Bill, W6WRT

One statement that IS True, and has been around "Forever":

Ground is not Ground, the World Around........


Me and RF Ground, is not Ground Ground........

As was pointed out before and mentioned by someone else, if the antenna
is mounted so as to be fed by a feed-line running at ground level AND
fed at this low point (coax probably best in such close proximity to
"ground ground")--and a set of rf grounding radials emanate in all
directions from this feed point (but just below ground), BOTH EARTH
GROUND and RF GROUND are at or "are very near" exact points.

For most other situations which come to mind, your statement is true.

JS

Bill Turner wrote:
ORIGINAL MESSAGE:

On Sun, 12 Nov 2006 15:14:49 -0000, "Dave" wrote:


but rf doesn't flow 'into the earth'

------------ REPLY FOLLOWS ------------

Beware of making broad statements that are supposed to be true in all
cases. The one above is not.

Bill, W6WRT

Bill,

The broadest and most general statement I made in my post was "All real
world implimentations of "RF ground" are less than perfect". I take it
from your negitive post that you disagree with this point.

David wrote:
What would you define RF ground as? There seem to be a lot of different
ideas

An ideal RF ground is a point or node where RF current can be imposed
and the result is no change in RF potential (voltage). That is to say
the impedance is zero. All real world implimentations of "RF ground"
are less than perfect as measured by their real world impedance.