Baluns?
 

On Sep 3, 10:43*pm, John Smith wrote:
wrote:
...
I agree that a balun operating at 14 MHz would be a choke when
operating at 70MHz.

Oh, gee, then you would also agree that a ferrite core around a power
supply lead would begin to act as a reactance when the DC line had an AC
component travel its' conductive route--you will be happy to realize
most would concur! *ROFLOL

Lame ... need I really add more?

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

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?

Baluns?
 

On Sep 3, 10:45*pm, John Smith wrote:
wrote:

* ...





I wouldn't say it was choking the common mode.mode current, I would
say it is isolating it from diff mode current by simply creating an
isolated ground reference point (you could define it at centertap if
you were so inclined). Of course I would agree that the impedance
between diff mode current at the input and CM current in the output
had better be very high, infinity would be best, *but the finite
impedances to load and source respectively should match the balun. 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. Also, if the W2DU balun is
referred to as the "ugly balun", I do believe the use of a bifilar
winding around an air core to create an RF transformer has been around
for more than 100 years so I do not understand why it is so-named
after a contemporary ham. It is rather simple to go from bifilar
enameled copper to using the shield and inner conductor of a coax as
"bifilar" conductors. All of this stuff is pretty basic EE (Associate
level, not even Bachelors) and I hesitate to spend much more time on
it.

One thing I can say for sure, you are an idiot ... good luck.

What an utter waste of time ...

Regards,
JS

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.

Baluns?
 

On Sep 3, 10:47*pm, John Smith wrote:
wrote:
...
Because the input and the out windings of the balun must be isolated
at least at RF of interest, OF COURSE there should be a high impedance
between the ballanced current flow and the unbalanced current flow.
However, the impedance of the source looking into the impedance from
the souurce should match source impedance and the impedance of the
load looking in the output winding of the balun should match the load
impedance (say 70 ohms, or 600 ohms or whatever your antenna or
trnasmission line impedance is. The impedence at frequency of interest
between input winding and output winding should be infinity for
isolation purposes (obviously you do not want to mix the unbalanced
input and balanced output currents.

Hey, are you just a plain idot, or someone who lacks any ability at all
to apply logic? *ROFLOL

In all my time here, years!, I have never seen as large an idiot as you!
* My Gawd, you make the dummies here begin to seem logical!

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.

Common and Differential Modalities
 

Jerry wrote:

...
I realize that you have asked this question to Richard, who is far better
prepared to answer than I am.
...
Jerry KD6JDJ



Huh, didn't know you liked Shakespeare that much. Let me get to the
library and dust off the old tomes for you ...

Regards,
JS

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

Common and Differential Modalities
 

Jerry wrote:
... was expecting some
lanswer ...
...
Jerry

Good, you are expecting it then, an lanswer (lame answer.)

Regards,
JS

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

Common and Differential Modalities
 

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

Common and Differential Modalities
 

Baluns?
 

On Sep 3, 10:54*pm, John Smith wrote:
wrote:

A 1:1 balun IS an RF transformer. Lengths of transmission line wound
an air core can function as a 1:1 RF transformer. Does this in any way
show you the error you are making? Transformers operate in the same
way whether at 60Hz or RF. So much for your "No" statement which seems
to demonstrate a certain confidence masked in senility.

Actually, NO!

A 1:1 balun is a TLT, as stated, properly, by Ownen ...

But, what you speak of is frequently an RF Transformer ... how you keep
repeating that mistake speaks to your in ability to do research and
educate yourself ...

it's not the heat it's the senility

Common and Differential Modalities
 

On Wed, 3 Sep 2008 16:14:23 -0700 (PDT), wrote:

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.

I have explained it and I see nothing in your query that changes any
particular. Multiple phases compounds the complexity, it doesn't
change first principles. The terminology and usage have been long
established and I have described everything by those conventions.

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.

RF transmission line transformers DO NOT HAVE TO employ squared turns
ratios linked through magnetic flux. The purpose of successful BalUn
core designs is to isolate input from output, not to perform magnetic
coupling. Hence the topic of choking being so tightly conjoined with
RF Z transformation.

Modern BalUns, by this design, exhibit far wider bandwidths of
operation than would be exhibited by traditional flux linked
transformers. More so, the cores used for modern BalUns would roast
in a millisecond under those traditional flux linked conditions where
they can easily pass huge amounts of power differentially, and
suppress Common Mode currents.

The two design principles are vastly different, but serve the same
goal and employ the same terminology: both being called
"transformers." One very obvious confounding example to flux linkage
is the halfwave coaxial BalUn that is fed in parallel and loaded in
series to transform the unbalanced line input from 50 Ohms to the
balanced load output of 200 Ohms. No cores or turns ratios were
employed to accomplish what the isolation of the line provided
naturally. It is confined to a narrow range of frequency, but
conceptually replacing the isolation of line length with the
application of choking extends its coverage by orders of magnitude.

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.

Choking, shielding, and isolation - all of a piece - is a very
complicated topic and generally dismissed inappropriately. The
complexity lies in the breadth of application demands. Analysis
proceeds by simple concepts, certainly, but this does not abstract to
simple solutions.

I will again repeat the admonition that choking a transmission line
does NOT choke each lead individually (which appears to be your sole
experience dominated by RFI suppression in 60Hz applications). If
this singular statement is cryptic, then you should invest your energy
in the study of how the core isolates the input from the output of any
"Guanella BalUn." A perfectly good tutorial has already been
recommended to you by Roy.

73's
Richard Clark, KB7QHC

Baluns?