Hmmm...
Is it possible there are multiple meanings of the word "balun" - some of
which are technically correct, while other, more casual uses are used in
the vernacular, but not technically correct?
Hams use the word "balun" rather loosely, as if it is a broad rubric
including all sorts of diverse devices. Are all of these things
properly called a "balun" correctly labeled? Or, is it possible the
word is, at times, applied incorrectly?
I figure I am smarter than the average bear. If I can read Kant's
"Critique of Pure Reason," and understand Russell and Leibniz on the
logic of language, perhaps I can comprehend what I read about baluns.
OK... maybe not. But read Jim's paper on RFI, and admit I am still a
little corn-fused.
I agree the literature is neither clear nor consistent as to what is
called a "balun." A professor of electrical engineering down in Texas
once explained there is a material difference between "choke" and
"transformer," yet, hams often call each of these things a "balun."
I once thought a balun is a type of choke used to minimize common mode
current which may arise from an imbalance among antenna system
components, while a a transformer "transforms" a difference in
impedance among antenna system components.
It appears some devices have a singular purpose, while others have
multiple purposes. For example, one might employ a 1:1 balun (i.e.,
choke) at the feed point of a dipole to minimize common mode current on
a coaxial transmission line. In the case of an off center fed (OCF)
dipole, one might employ a 4:1 transformer (as an impedance
transformer) to more closely match the antenna's impedance to that of
the transmission line and radio. Such a device might even do double
duty to both transform impedance AND impede common mode current.
Hams seem to refer to ALL these singular and multi-purpose devices as
"baluns." Is this correct? Are really they all "baluns," or are we
being sloppy or careless in our usage? Is a transformer a balun, and a
balun a transformer? Is everything I see called a balun, really a
balun? Or some other device, deserving a more particular name?
How about providing basic definitions for each such device? It is off
base to think the literature lacks precision and consistency? What IS
the proper scope of each of these words - all of which are called a
balun by many hams?
1) balun
2) choke
3) transformer
4) current balun
5) voltage balun
6) choke balun (or balun choke)
7) common mode choke
8) inductive common mode choke
9) resistive common mode choke
10) 1:1 balun
11) 1:1 sleeve balun
12) 4:1 balun
Is the scope of each of these words so varied and amorphous we cannot
quickly say what each of these words mean? Is there some legitimate
confusion over what these words mean?
----------------- K8JHR ----------------
On 11/1/2013 3:54 PM, Steve Hunt wrote:
I'm surprised you feel so strongly!
Throughout your RFI tutorial I see many references to the term "current
balun". In a couple of places you put the term in parenthesis, or
explain that it is really a common-mode choke; but in many other places
the term is unqualified, and clearly is describing a common-mode choke.
Chapter 6 is even headed "Baluns". In my view, anyone reading the paper
could be forgiven for thinking that the correct term to use is "current
balun".
Personally I have no problem with the term; if you choke (impede)
common-mode currents, you are driving current balance.
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