hi

Over the years, I've found it interesting and disturbing even
confusing, that there seems to be so much confusion regarding the
above.

Nothing gets a post responce, like the above topic and boy those
threads quickly grow to large numbers

I always read them trying to learn as well as books on the topics,
i don't pretend to have any formal engineering /scientific
knowledge just enjoy reading what i can

but i ponder why there seems to be so many opposing /contradicting
views on same subjects and topics and i am not referring to just
those here on the news groups

if i get x people in a room ask about baluns or chokes 1/2 say one
thing the other 1/2 say something else

dunno it's strange in all that confusion obviously we all pick
what we interpert and believe to be best but i hate when that happens

ml wrote:
dunno it's strange in all that confusion obviously we all pick
what we interpert and believe to be best but i hate when that happens

Baluns are not unique. Religions, politics, investment advice,
brands of vehicles, flavors of ice cream, sexual attraction,
life styles, ... - "We all pick what we interpret and believe
to be the best" in virtually every aspect of our lives.

My personal preference is a 1:1 current-choke-balun with
thousands of ohms of choking impedance, either resistive
and/or reactive.
--
73, Cecil http://www.w5dxp.com

"ml" wrote in message
...
hi

Over the years, I've found it interesting and disturbing even
confusing, that there seems to be so much confusion regarding the
above.

Nothing gets a post responce, like the above topic and boy those
threads quickly grow to large numbers

I always read them trying to learn as well as books on the topics,
i don't pretend to have any formal engineering /scientific
knowledge just enjoy reading what i can

but i ponder why there seems to be so many opposing /contradicting
views on same subjects and topics and i am not referring to just
those here on the news groups

if i get x people in a room ask about baluns or chokes 1/2 say one
thing the other 1/2 say something else

dunno it's strange in all that confusion obviously we all pick
what we interpert and believe to be best but i hate when that happens

yeah, i just hate it when that happens... it all stems from many old myths
and misconceptions about what baluns do, or don't do... and confusing them
with coax cable chokes.

One important note... coax IS a balanced transmission line, its just that
the current that balances the one on the center conductor is confined
(normally) to the inside of the shield.

i look at it this way:

a 'true' balun is a transformer that converts from balanced to unbalanced
lines, it may or may not also transform impedances. this is the type of
thing you would put in between a coax and an open wire feeder, or what is
included in many tuners that are fed with coax and have balanced outputs.
in the degenerate case, which is actually now the most common use, the
balanced line is shortened to nothing and the balun is at the feedpoint of
the dipole or yagi driven element.

the coax choke is often confused with a balun because it is also used at a
balanced antenna feedpoint, but the actual physics of it is much different.
if you just connect a dipole to a piece of coax with no choke you really
have a 3 legged 'dipole'. current going out the center conductor wants to
return on the INSIDE of the coax shield... however there are 2 paths for
this current to take. it can come from the other side of the dipole, the
intended path, or it can come from the OUTSIDE of the shield up to the
feedpoint then back to the INSIDE of the shield... this is the one that
causes trouble. Not only is it usually vertically polarized instead of
horizontal like the intended current which distorts the pattern. But it is
also not just confined to the coax near the antenna, it can also exist on
the outside of the shield all the way back to the shack. Now, a choke on
the outside of the shield, either by winding coils of coax or adding ferrite
beads creates a high impedance bump between the shield below the choke and
the inside of the shield at the feed point. This high impedance reflects
any current on the outside of the shield back down, out of phase, thus
effectively canceling it out. This means the only route back for the
current to the inside of the coax shield is from the intended side of the
radiator... thus it forces a balance in the currents, but through a slightly
different mechanism than a 'true' balun transformer. Personally i prefer
the coil method because all it costs is a bit of coax. The ferrites that
are often used can have some unintended effects. first, they are lossy, and
some people assume this is their intended mode of operation and use even
lossier ones than they should. this results in heating at high power and
loss of transmitted power in the choke. also at high power if the cores are
not big enough they can saturate which causes harmonics and even more heat
plus a loss of effectiveness. The more correct way to look at it is as a
single turn choke, the ferrite core should present as high an impedance as
possible with as little loss as possible at the frequency its being used at.
This reduces losses and the associated bad effects. also note that the coax
choke can not transform impedances, the feedpoint must be matched to the
coax.

but i ponder why there seems to be so many opposing /contradicting
views on same subjects and topics and i am not referring to just
those here on the news groups

if i get x people in a room ask about baluns or chokes 1/2 say one
thing the other 1/2 say something else

dunno it's strange in all that confusion obviously we all pick
what we interpert and believe to be best but i hate when that happens

It's real easy to get caught up the definitions. A transformer transforms
impedance, voltage or current and often isolates but not necessarily. A
choke uses the magnetic field created by the AC current through it to oppose
that current. The wiki points out there are balanced and unbalanced
signals. Webster says balanced and unbalanced lines. Someone posted that
coax is in fact a balanced line. OK that can be oddly true, but it can be
unbalanced by how you connect it. So it can be part application, part
configuration, part common word usage that might not be purely accurate, and
where you are focusing your attention.

Still, it can be many prefer to be an expert and argue and make statements
rather than ask the questions. I must confess after a project, I often let
details slip by me unlike day to day operations that I can't get out of my
head 30 years later. I can still align Micor and Motrac radios in my sleep
step by step.

The whole discussion could have all been on a roundtable net but then we
wouldn't have the luxury of nit-picking and cussing each other out.

Dave wrote:
This means the only route back for the
current to the inside of the coax shield is from the intended side of the
radiator... thus it forces a balance in the currents, but through a slightly
different mechanism than a 'true' balun transformer.

Sevick suggested that the word transformer *NOT* be used
with baluns. He said, in "Building and Using Baluns and
Ununs":

"By far, most misconceptions regarding baluns are due
to the many radio amateurs who perceive these devices
as conventional transformers that transmit the energy
from input to output by flux linkages and not as
transmission line transformers, which transmit energy
by an efficient transmission line mode."

"If the writers had accepted the correct model for
these devices (given to us by Guanella and Ruthroff),
which shows that *THEY ARE REALLY CHOKES* (lumped
elements) and configurations of transmission lines
(distributed elements), ..." emphasis mine.

"In fact, the perception that the transmission line
transformer is actually a conventional transformer
is so prevalent, that a new name for this class of
devices should be considered -
*broad band transmission line matching networks*.
This name (without the word transformer) would help
in dispelling inaccurate perceptions and in
standardizing the schematic diagrams."
--
73, Cecil http://www.w5dxp.com

JB wrote:
I can still align Micor and Motrac radios in my sleep
step by step.

Using megacycles and condensers, no doubt. :-)
--
73, Cecil http://www.w5dxp.com

On Fri, 05 Sep 2008 08:56:34 -0400, ml wrote:

but i ponder why there seems to be so many opposing /contradicting
views on same subjects and topics and i am not referring to just
those here on the news groups

Hi Myles,

Most of this "controversy" extends from the lack of experience. Quite
a natural condition for some amateurs. This will change if they are
interested - interest also being a common condition for amateurs.

Those with a technical bent (rather than simply being interested in
operating) will sit at the bench and figure out this topic of baluns n
chokes n stuff. Then it won't be the controversial mystery it seems
to be for those who don't.

73's
Richard Clark, KB7QHC

ml wrote:
hi

Over the years, I've found it interesting and disturbing even
confusing, that there seems to be so much confusion regarding the
above.

Nothing gets a post responce, like the above topic and boy those
threads quickly grow to large numbers

I always read them trying to learn as well as books on the topics,
i don't pretend to have any formal engineering /scientific
knowledge just enjoy reading what i can

but i ponder why there seems to be so many opposing /contradicting
views on same subjects and topics and i am not referring to just
those here on the news groups


Several reasons..
1) the terminology isn't necessarily consistent in its definition

2) the things get used in a complex system with lots of interactions, so
it's hard to separate out the effects of the function of component A
from those of components B,C,D, and E.

3) there's a host of empirical evidence out there that seems to
contradict the theoretical behavior of A (mostly because the empirical
evidence also includes the behaviors of B, C, D, and E, which aren't
always controlled for or understood). So you wind up with "A does X" in
system 1, and "A does Y" in system 2.

"Cecil Moore" wrote in message
...
JB wrote:
I can still align Micor and Motrac radios in my sleep
step by step.

Using megacycles and condensers, no doubt. :-)
--
73, Cecil http://www.w5dxp.com

Those were in the Pre-Progs.

In article ,
Cecil Moore wrote:

ml wrote:
dunno it's strange in all that confusion obviously we all pick
what we interpert and believe to be best but i hate when that happens

Baluns are not unique. Religions, politics, investment advice,
brands of vehicles, flavors of ice cream, sexual attraction,
life styles, ... - "We all pick what we interpret and believe
to be the best" in virtually every aspect of our lives.

My personal preference is a 1:1 current-choke-balun with
thousands of ohms of choking impedance, either resistive
and/or reactive.

wanted to say thanks much to all those that responded really
appreciate the thoughts

i guess for me, the 'easy ' way out (when in doubt) is after i do
something to take measurements, if i dont see what i should i
presume i did it wrong,

never hurts to double check with testing or to buy test gear and
tools

thanks again all