wrote:

...
You reference line 1 to line 2. You put your RF voltmeter acroos the
two conductors. When doing so you measure two times the voltage that
line 1 or line 2 reads with respect to an imaginary isolated grounbd
at the centertap the line 1 or 2 measures separately with respect to
centertap. OF COURSE the summation of all points on the common
reference is zero at all locations at all times, that is why it is
called an isolated "ground"! That is why I said earlier you could
connect the centertap of the isolated CM side to real ground with no
effect on the circuit in an earlier post.

Yanno, I think you have Legos confused with antennas. What does it say
on that box that your mom bought you?

Regards,
JS

--
It is like a nightmare where the public servants are the people which
the police are supposed to protect us from!

wrote:

...
Coming from you that is a compliment. I recommend you stop wasting
your time on things you know nothing about. If you agreed with me,
then I would have to take another look at what I was saying.


Yes, well, I am quite happy you are pleased ... hey, are you related to
richard?

Regards,
JS

--
It is like a nightmare where the public servants are the people which
the police are supposed to protect us from!

wrote:

...
I am not sure where you are coming from. Are you trying to say that
differential mode interference often exists alongside CM interference
and diff mode can be filtered by coiling phase wires over a ferrite
core? Works for me. I agree. Now, what has that got to do with the
discussion?

Fool, I think "differential mode" is the "mode of the day!" (gawd I hate
that word ... :-( )

However, common mode, as many have tried to explain to you, is a bad
trip ... but then, you should know that.

Regards,
JS

--
It is like a nightmare where the public servants are the people which
the police are supposed to protect us from!

wrote:

...
Please plonk me. I don't know how to plonk you using this google web
interface...unless you have instructions. I note you do a lot of
plonking. And its not due to the heat, it's the senility.

Naw, I take a particular bizarre interest in serial murders, rapists,
etc. The wife and I just can't get enough of those weird crime shows
.... you are even better than that/those!

Regards,
JS

--
It is like a nightmare where the public servants are the people which
the police are supposed to protect us from!

Richard Clark wrote:

...
73's
Richard Clark, KB7QHC

By all means, proceed. However, fair warning, I stopped reading any
posts, by you, long ago ... I find that all I can muster is caustic
comments from here on out ...

Regards,
JS

--
It is like a nightmare where the public servants are the people which
the police are supposed to protect us from!

wrote:

...
it's not the heat it's the senility

Be careful, a heat rash like that in the pubic area might be the sign of
a larger problem ... perhaps the whores on 65th street are better left
to themselves ... something to consider anyway.

Regards,
JS

--
It is like a nightmare where the public servants are the people which
the police are supposed to protect us from!

On Wed, 03 Sep 2008 19:49:55 -0700, John Smith
wrote:

My gawd,
inappropriately addressed - but accepted nonetheless.
an idiot which
who
takes a hundrend
hundred
sentences to say
write
a simple point
is little better than an idiot which
who
cannot even generate
write
one sentence!

Only a little better? Do you have a sentence, or is this another
obscure sentiment?

73's
Richard Clark, KB7QHC

"Mike Coslo" wrote in message
36...

Do your prayers make any difference, they really don't, because God knew
you were going to pray, and he knew his response. You had no choice. You
did what you did because God made you do it that way.

This of course means that God knows the predestination of every person he
created, which means that he knew that he was knowingly condemming a whole
lot of people to an eternity of torture.

I picked up on these and other inconsistencies in the early 1970s. I've
been an atheist ever since.

I wish some few atheists weren't such activists about it, though. It gives
us bad PR and turns atheism into a religion.

wrote in message
...
On Sep 3, 10:54 pm, "Jerry" wrote:
wrote in message

...
On Sep 3, 3:59 pm, Richard Clark wrote:





On Mon, 1 Sep 2008 09:26:26 -0700 (PDT), wrote:
In a perfect situation, with a balanced feedline, the only kind of
current and voltage you have IS common mode!

This statement above contains a serious error of perception while
trying to inhabit the debate over BalUns - and it probably corrupts
that topic too.

First - a circuit has at a minimum two conductors extending from a
source. A circuit by its nature is circular: for every charge carrier
that enters it, one must exit it. Continuity is a necessary condition
for a circuit. No continuity, no conduction, hence an "Open Circuit."

Second - those two conductors, if viewed at a remote point where they
are joined, have equal and opposite paths of current conduction - to
and from that point. This is from Kirchoff's law of currents.

Third - this is called Differential Mode current in anticipation of a
common modality.

Fourth - if that remote point of connection is replaced with a load,
there is a voltage across that load characterized by both the
unaltered directions of current, and its now altered magnitude of
current.

Fifth - this is called Differential Mode voltage in anticipation of a
common modality.

This completes the discussion of the Differential Mode.

If we expand upon this simple model of a source, two wires, and a load
and put it into the context of life as we know it; then the circuit
operates in the proximity of ground. By convention, ground is called
Common.

Ground, by convention is an infinite sink of charge of infinite
extent. Hence as a conductor, it is available everywhere - Common.
This ground may have either deliberate or accidental conductive
relationships to the Differential Circuit.

First - the linkage of ground to the differential circuit can be
through an Ohmic path, or by an inductive path, or by a capacitive
path. To support conduction, the circuit must contain two conductive
paths to ground through any combination of these linkages, and that
path must be complete. The apparent source driving conduction through
that path will be a combination of the differential source and the
differential load as each will have some relationship to ground.

Second - those two conductive paths, if viewed at a remote point
where they are joined, have equal and opposite paths of current
conduction - to and from that point. This is from Kirchoff's law of
currents.

Third - this is called Common Mode current.

Fourth - as the differential circuit is original and establishes both
the source and the load; then through the introduction of ground, this
Common Mode current is mixed with the original Differential Current
and analysis must be performed by substitutions to separate them.

Fifth - the apparent source presents the Common Mode voltage.

This completes the discussion of Common Mode.

The applications of a choke to either circuit is commonplace to
control each mode's current. It would appear through the context of
discussion in other threads that there is some confusion in what is
being choked, and how a choke is properly applied is confounded by
that confusion.

It follows that if the transmission line from the source to load
suffers from Common Mode currents, that this must be due to a Common
Mode voltage gradient extending from the source to the load. If
either lead of that transmission line pair were choked, this would
disrupt the Differential Mode. If both leads of the transmission line
pair were independently choked, this would only double the disruption.
However, if both leads were choked in parallel (both lines either
coiled as a pair rather than individually, or both lines penetrate a
lossy core) then their fields would be contained between them in the
Differential Mode, but their Common Mode path (they both share equal
conduction in the same direction due to the Common Mode voltage
gradient) will be snubbed.

Some BalUns employ these techniques - some don't. BalUns fail by the
degree that they don't when Common Mode, as a problem, is injected
into the circuit through imbalances. As balance in the proximity of
earth and many confounding nearby structures is a forgone failure,
choking is a practical necessity for correct BalUn performance. Any
issues of BalUn heatings are proof of this choking necessity, and
further proof of the demand for additional choking at that point (and
frequently elsewhere at wavelength relationships along the affected
line).

73's
Richard Clark, KB7QHC

Let me put it this way (again very simplifed): How do you explain a
residential 208V power source where you have 120 V from line 1 and
line 2 to ground but 240V with respect to each other. You 240V
household appliances operate this way. Ecept for the fact that the
lines are 120 degrees out of phase phase (insread of 180 because we
use a delta system instead of Y, but this is not that important for
this discussion) this is nearly a BALANCED feed, where lines 1 and 2
degrees out of phase at 60 Hz and the voltage of interest is the
summation of the two lines. Nearly every home in the USA operates this
way. In Europe, 240 V is usually obtained by the voltage difference
between line 1 (240V) and earth (0V). That is an unbalanced feed. You
can insert a 1:1 isolation transformer using the European system at
the input and create the balanced USA system at the output by drawing
+120 and -120 at from the output windings assigning imaginary isolated
earth at centertap. The isolated ground CANNOT conduct tio real ground
if the winding to winding impedance is infinity. Basically, hams' 1:1
baluns do much the same thing: They isolate the real ground as such
and prevent currents from flowing down the input ground shield. On
this ng in a short space I cannot think of a simpler way to express
this although I expect to see many statements (you can't equate 60Hz
to RF!). Yes you can; a transformer operates as a transformer in the
same wayat any frequency providing you design it properly for the
frequency of interest. This subject is not nearly so complicated as
some in this group makes it out to be and the topic certainly does not
rate articles in amateur publications any more than basic application
of ohm's law does.

Hi Dfinn

I realize that you have asked this question to Richard, who is far better
prepared to answer than I am. But, it seems that you are confused about
how two sine waves add. Maybe I am wrong, and you do know how two sine
wave
voltages generated at different times and are connected in series combine
to
being other than 180 degrees from terminal to terminal.
All the 208 power lines I am familiar with *are* 208 from terminal to
terminal when each leg is 120 "terminal to center". Where did you get the
"240"?

Jerry KD6JDJ- Hide quoted text -

- Show quoted text -

I tried to explain this one failure in my model; it is truely of phase
difference of 120 degree, thus you get only 240/SQRT(3) = 208 RMC when
measuring from phase 1 relative to phase 2. The cure is to imagine a Y
network instead of a delta network; it is much easier to conceptualize
but they are not used so much in the US anymore

Hi Dfinn

Where do you measure voltages on any two terminals to get a 120 degree
phase reading in
a three phase system? How do you divide 240 by the square root of 3 and
get 208?

Jerry KD6JDJ

wrote:
If
you want to call the ground isolation function "choking", that use of
this colloquialism is fine with me but FYI that is not the traditional
vernacular for that that application.

In 1953, my first ham transmitter had an RF choke to allow
DC to reach the 6146 plate while choking the RF thus forcing
it to follow a different path through the pi-net. RF "chokes"
have been around since before I was born.

From "The IEEE Dictionary": "choke - a device for preventing
energy ... in a given frequency range from taking an undesired
path."

That's exactly what the RF choke in my Globe Scout did in
1953 and that's exactly how a W2DU balun works today.
--
73, Cecil http://www.w5dxp.com