I apologize to Mike for hijacking his 160m matching problem with my choke
and balun comment.
Also, I was very vague with my statement.
I will try again, being more specific:
....When used directly at the feedpoint of an antenna or together with an
Antenna Tuner for matching Openwire feedlines, a balun is an RF choke and an
RF choke is a balun. They are the same animal in these applications.
Of course there are other applications where they differ. I know that.
I was just thinking with respect to the antenna topic we were discussing.
By combining multiple (optional) balun transformers, we may create a
transmission line transformer (TLT), but if together they do not do a
sufficient job of impeding common mode current, they are not doing the job
of a good balun (for this application). In my opinion, it is wrong to call
these a balun.
In the case of using a W2DU "whatever" as a balun, Sevick calls it a "Choke
Balun".
But the devices currently sold on the market as W2DU baluns (or chokes) are
not like the original W2DU design.
"Semantics" plays a big role here with this topic.
I believe semantics contributes to the misunderstanding of baluns.
It would be great if someone or some group of experts would agree on what we
call these.
AND if there is already such an agreement, it would be nice to see it
printed in magazines or books that we all read.
However it needs to be short and easy enough for everyone to understand, not
just EE's.
Trying to learn about this topic from the Internet is like trying to do
brain surgery on yourself.
73
Rick, DJ0IP
-----Original Message-----
From: TenTec [mailto:tentec-bounces@contesting.com] On Behalf Of Jim Brown
Sent: Friday, November 01, 2013 2:43 AM
To: tentec@contesting.com
Subject: Re: [TenTec] 160 meters, ten ted 238 tuner, part two
On 10/31/2013 2:39 PM, Rick - DJ0IP / NJ0IP wrote:
> A BALUN and an RF Choke are synonymous. They are the exact same thing
> (except for the connection terminals).
This is TOTALLY WRONG!
I know of nearly a dozen VERY different things that are described by the
word "balun."
An RF choke is an inductor, and it some frequency it will resonate with its
own stray C.
A coil of coax is an inductive common mode choke -- the fact that it is
inductive makes it a LOUSY common mode choke. It is often called a balun.
A coil of coax wound through lossy ferrite cores is a RESISTIVE common mode
choke -- resistive because the ferrite core is lossy, because it resonates
with its own stray C, and the choke has been wound to place the resonance
in the range of frequencies where we need a choke.
A bunch of ferrite beads on a piece of coax is a common mode choke. Most
such "string of beads" chokes are inductive, which makes them lousy common
mode chokes. The original W2DU common mode choke that he called a current
balun used 100 or more #73 ferrite beads, which are made only in a size
that fits small diameter coax (RG58), and which DO have the desired low Q
(very lossy) resonance in the HF bands. These original W2DU chokes are GOOD
common mode chokes.
A half wave of coax has used as part of the feed of monoband antennas, and
that is called a balun.
There are arrays of common mode chokes (series/parallel) that used to
transform impedance and are called baluns.
There are multi-turn transformers that are called baluns.
There are active electronic products that drive video onto CAT5 cable that
are called baluns.
All of these are VERY different from each other. None of them are an RF
Choke.
73, Jim K9YC
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