Richard Clark wrote:
wrote:
Many US amateurs do not understand how a balun works.

How true - not even fundamental terminology.

http://en.wikipedia.org/wiki/Balun (see 1st photo)
"This is a simple RF *choke* which works as a *balun* by
preventing signals passing along the outside of the braid."

From "The IEEE Dictionary":
"balun (1) A network for the transformation from an
unbalanced line or system to a balanced line or system,
or vice versa."

From an Unabridged Webster's:
"balun - a device for converting a balanced line into
an unbalanced line and vice versa."

10 PRINT "A W2DU balun is both a choke and a balun!"
20 Goto 10
--
73, Cecil http://www.w5dxp.com

On Sep 3, 2:10*pm, Cecil Moore wrote:
Richard Clark wrote:
wrote:
Many US amateurs do not understand how a balun works.

How true - not even fundamental terminology.

http://en.wikipedia.org/wiki/Balun(see 1st photo)
"This is a simple RF *choke* which works as a *balun* by
preventing signals passing along the outside of the braid."

*From "The IEEE Dictionary":
"balun (1) A network for the transformation from an
unbalanced line or system to a balanced line or system,
or vice versa."

*From an Unabridged Webster's:
"balun - a device for converting a balanced line into
an unbalanced line and vice versa."

10 PRINT "A W2DU balun is both a choke and a balun!"
20 Goto 10
--
73, Cecil *http://www.w5dxp.com

I agree that a balun operating at 14 MHz would be a choke when
operating at 70MHz.

wrote:
I agree that a balun operating at 14 MHz would be a choke when
operating at 70MHz.

You would do well to agree that a well-designed W2DU balun
operating at 14 MHz is choking the heck out of the 14 MHz
common-mode current in order to achieve the balun function.

You seem to have the IEEE definitions of differential
signals and common-mode signals exactly reversed. Because
of that misconception, might you be the one who doesn't
understand how baluns work?
--
73, Cecil http://www.w5dxp.com

On Sep 3, 7:18*pm, Cecil Moore wrote:
wrote:
I agree that a balun operating at 14 MHz would be a choke when
operating at 70MHz.

You would do well to agree that a well-designed W2DU balun
operating at 14 MHz is choking the heck out of the 14 MHz
common-mode current in order to achieve the balun function.

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.

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

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

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.

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:
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

On Sep 3, 7:18*pm, Cecil Moore wrote:
wrote:
I agree that a balun operating at 14 MHz would be a choke when
operating at 70MHz.

You would do well to agree that a well-designed W2DU balun
operating at 14 MHz is choking the heck out of the 14 MHz
common-mode current in order to achieve the balun function.

You seem to have the IEEE definitions of differential
signals and common-mode signals exactly reversed. Because
of that misconception, might you be the one who doesn't
understand how baluns work?
--
73, Cecil *http://www.w5dxp.com

Cecil, if a transmission line operated in the way you think, it would
be radiating fields all along its length transmitting RF all along the
length of the line. Nothing would get the antenna. The conductors in
the lines MUST carry mirror image currents and voltages to indeed
cause the cancellation of fileds you speak about. THAT is how energy
gets to the antenna. Ever hear of a ground loop?

wrote:
Cecil, if a transmission line operated in the way you think, it would
be radiating fields all along its length transmitting RF all along the
length of the line.

False! This is easy to visualize and prove. Given a 1/2WL
folded dipole fed with 300 ohm balanced line:

1. Do the out-of-phase differential transmission line
currents radiate? Ideally - NO!, because the fields
from the two wires engage in destructive interference
and cancel.

2. Do the in-phase antenna currents radiate? YES!, just
as they are supposed to do because the fields from the
two wires engage in constructive interference and re-
enforce each other.

Let's look at the balanced output terminals of the current
balun at the source. Instantaneous current is flowing out
of one terminal while instantaneous current is flowing into
the other terminal. I'm sorry, but that is differential,
transmission line current.
--
73, Cecil http://www.w5dxp.com