Ralph Mowery wrote:

I don't see wasting time or money on a balun for just a simple dipole
. Sure it may make the patern vary from the normal textbook, but who
cares most of the time. Most people have to put the antenna up
wherever they can and lots of time it is not in the desired direction
anyway.

Very often, those are the same people who complain of "poor conditions"
and "noisy bands", and operate in constant fear of causing RFI. Many of
these problems are simply due to common-mode feedline currents bringing
RF back into the shack and coupling into the mains wiring.

In other words, people with limited antenna opportunities are often the
ones who need a balun - or more accurately, a common-mode choke - the
MOST.

The problems of desperate antenna locations cannot be entirely cured,
but they *can* be improved. Almost always, feedline chokes and/or baluns
will have a valuable part to play.

NOw a beam or some other antenna design is differant.

The largest difference is in the attitudes of the users. No matter what
your antenna is, or where you're forced to install it, it all comes down
to one simple question: do you want to give this antenna the best
possible chance to work correctly... or not?



--

73 from Ian GM3SEK 'In Practice' columnist for RadCom (RSGB)
http://www.ifwtech.co.uk/g3sek

Technically I would have to disagree with calling even a 1:1 balun the
same thing as a common mode choke. A CM choke is an EMI prevention
device intended to filter out RF components generated in a circuit,
away from the feed of a power source, usually an electrical mains. A
balun is intended to change the feed from an unbalanced transmission
line to a balanced output, for example, for connection to a balanced
transmission line or to an antenna such as a dipole. With the balun,
we wany NO reduction in RF current flow. I agree that the effect is
the same, semantically, ie one side effect of the use of a balun is
less CM interference from coming down a balanced feedline but it is
there for a different reason.

Dan

On Aug 28, 2:26*am, Ian White GM3SEK wrote:

In other words, people with limited antenna opportunities are often the
ones who need a balun - or more accurately, a common-mode choke - the
MOST.

Dan wrote:
On Aug 28, 2:26*am, Ian White GM3SEK wrote:

In other words, people with limited antenna opportunities are often the
ones who need a balun - or more accurately, a common-mode choke - the
MOST.

Technically I would have to disagree with calling even a 1:1 balun the
same thing as a common mode choke. A CM choke is an EMI prevention
device intended to filter out RF components generated in a circuit,
away from the feed of a power source, usually an electrical mains.

That is too far narrow a definition of a "common mode choke",
especially the reference to electrical mains. The term is widely applied
to transmission line for both digital data and analog RF signals.

A
balun is intended to change the feed from an unbalanced transmission
line to a balanced output, for example, for connection to a balanced
transmission line or to an antenna such as a dipole. With the balun,
we wany NO reduction in RF current flow.

What exactly do you mean by that?

And also, what exactly do you mean by "balanced" in the context of a
feedline?

I agree that the effect is
the same, semantically, ie one side effect of the use of a balun is
less CM interference from coming down a balanced feedline but it is
there for a different reason.

Not in my station. My motivation for using common-mode chokes is
*specifically* to control any incoming and outgoing interference that
may be caused by common-mode currents on the feedline.

When the common-mode component of the feedline is reduced, it will also
be accompanied by an improvement in "balance" on the antenna, because
the two things go together (or at least, they do for some definitions of
that word). But "balance" is never my primary goal because I don't find
the concept helpful, either when deciding what to do next or when
evaluating the results.



--

73 from Ian GM3SEK 'In Practice' columnist for RadCom (RSGB)
http://www.ifwtech.co.uk/g3sek

wrote in news:c2a78f6b-eded-4547-ae32-bc8ccd60e186
@m73g2000hsh.googlegroups.com:

Technically I would have to disagree with calling even a 1:1 balun the
same thing as a common mode choke. A CM choke is an EMI prevention

I suggest that a reasonable definition of a balun is any device that
facilitates or assists transition from unbalanced to balanced mode of
operation. That definition permits a wide range of devices that may have
characteristics suited to specific applications.

(Keeping in mind that an unbalanced feedline is often not ideal in
application, ie one where common mode current is exactly half of the
differential current, and a two wire open line is often not ideal in
application, ie where common mode current is zero.)

Most people naturally think of balance in terms of voltages wrt some common
reference, eg ground. It is equally legitimate, and often more appropriate
to the antenna / feedline scenario, to seek balance in terms of current, ie
to minimise common mode current.

Owen

Everyone makes fun of newbies buying ready-built dipoles on eBay, but
nobody can direct you to where to buy baluns? Searched hi and lo
online, and what I found, was more expensive than buying a ready-made
dipole! I'd like to buy a balun, and attach my own cut-to-length
wire, but can't find cheap baluns ANYWHERE.

Where are you Elmers buying your baluns?


Every major amateur radio dealer I have bought from had baluns in their
inventory, Ham Radio Outlet and Amateur Electronic Supply, to name two.

However, you might find a wider selection from
http://www.radioworks.com



Ed K7AAT

On Wed, 27 Aug 2008 13:17:39 -0700 (PDT), dbc254
wrote:

Where are you Elmers buying your baluns?

I build my own. Some reading material:
http://www.dxzone.com/catalog/Antennas/Baluns/

However, if you wanna stimulate the economy, there are 7 commercial
balun reviews on eHam:
http://www.eham.net/reviews/products/1

--
# Jeff Liebermann 150 Felker St #D Santa Cruz CA 95060
# 831-336-2558
# http://802.11junk.com
# http://www.LearnByDestroying.com AE6KS

"dbc254" wrote in message
...
Everyone makes fun of newbies buying ready-built dipoles on eBay, but
nobody can direct you to where to buy baluns? Searched hi and lo
online, and what I found, was more expensive than buying a ready-made
dipole! I'd like to buy a balun, and attach my own cut-to-length
wire, but can't find cheap baluns ANYWHERE.

Where are you Elmers buying your baluns?

I don't bother with them. The ionosphere goofs up my pattern anyway.

dbc254 wrote in news:110c0833-aa68-4266-b599-
:

Everyone makes fun of newbies buying ready-built dipoles on eBay, but
nobody can direct you to where to buy baluns? Searched hi and lo
online, and what I found, was more expensive than buying a ready-made
dipole! I'd like to buy a balun, and attach my own cut-to-length
wire, but can't find cheap baluns ANYWHERE.

Where are you Elmers buying your baluns?


I think you haven't tried very hard.

No endorsement:

http://www.thewireman.com/baluns.html

The above will have components you can use to make your own... a real
learning exercise.

dxengineering.com

Owen

"dbc254" wrote in message
...
Everyone makes fun of newbies buying ready-built dipoles on eBay, but
nobody can direct you to where to buy baluns? Searched hi and lo
online, and what I found, was more expensive than buying a ready-made
dipole! I'd like to buy a balun, and attach my own cut-to-length
wire, but can't find cheap baluns ANYWHERE.

Where are you Elmers buying your baluns?

My last purchase was from HRO, about $25 for a 1:1 to use with a wire
dipole. Go to www.hamradio.com, enter balun in the search box and step
through the offerings with Adobe Reader.

Many hams will recommend you try a home-made balun, multiple turns of coax
cable wound neatly around a cylindrical form. Exact requirements and
effectiveness may vary with frequency and the antenna as installed. You
might want to look at http://www.qsl.net/ta1dx/amator/broadband_baluns.htm.
(It bothered me to see the letter W used for "ohms" in two places. I didn't
spot any other errors/typos but ...)

Also: http://www.hamuniverse.com/balun.html (many pictures)

Many hams will recommend you try a home-made balun, multiple turns of coax
cable wound neatly around a cylindrical form. Exact requirements and
effectiveness may vary with frequency and the antenna as installed. You
might want to look at http://www.qsl.net/ta1dx/amator/broadband_baluns.htm.
(It bothered me to see the letter W used for "ohms" in two places. I didn't
spot any other errors/typos but ...)



Also: http://www.hamuniverse.com/balun.html (many pictures)
================
Nice URL with excellent info
tnx

Frank GM0CSZ / KN6WH