On 9/9/2010 7:26 AM, lu6etj wrote:

...
Hello boys, good day for you

Is it Carolina Windom a balanced load to justify the name "balun"? We
could think in a device to transform Z and another device to block
feed line current. What do you think about it?

Miguel

Tell 'em one thing "balance" means is if you have a funky antenna
depending on feedline currents/radiation/etc. you don't start chucking a
bunch of stuff in the feedline without expecting patterns to change ...

Regards,
JS

lu6etj wrote in
:

Hello boys, good day for you

Is it Carolina Windom a balanced load to justify the name "balun"? We
could think in a device to transform Z and another device to block
feed line current. What do you think about it?


Miguel,

Sometimes the language we use doesn't well describe the thing we are
thinking about, and this is a case.

We could well apply a meaning to balanced, that either the currents are
equal in magnitude but opposite in phase; or that the voltages wrt some
sensible accessible reference are equal in magnitude but opposite in
phase. One does not imply the other without constraining the load
characteristic.

When we speak of unbalanced, we commonly think of a configuration where
one side is 'grounded' and the other 'active'.

The problem is that many situations in antenna systems are not purely
either, they are not balanced by one or other of the meanings above, and
they are not unbalanced by the meaning above.

So, they need to be dealt with by the more general method of considering
that there are non-zero common mode and differential voltages and
currents.

It would be most unlikely that a Carolina Windown would be balanced, or
near to it, by any defintion. The antenna is born out of a quest to sell
the disadvantage of Windom feedline radiation as a positive feature.

The way I like to explain a balun is that it *facilitates* connection of
a not-balanced device to a balanced device. A practical balun does not,
of itself, eliminate (meaning make zero) common mode current or common
mode voltage... yet we commonly use absolute words to describe its
action.

To a certain extent, that is saying that they are not ideal or perfect
devices. Some of the rules we hams have made for baluns pretty much
assure mediocre performance. Like for example what I refer to as Rule
500, that the minimum choking impedance of a current balun is ten times
the differential characteristic impedance (commonly 50, hence Rule 500).

I know English is not your first language, but be wary of applying the
meaning of words absolutely.

Owen

On 9 sep, 16:26, lu6etj wrote:
On 6 sep, 13:14, Wimpie wrote:



On 6 sep, 14:30, John Smith wrote:

On 9/6/2010 5:08 AM, Cecil Moore wrote:

...
The one I remember was about the Carolina Windom 4:1 voltage balun at
the feedpoint and the 1:1 choke-isolator 20' down the coax. The
original Windom was fed, Marconi style, against ground.
--
73, Cecil, w5dxp.com

I have a "weird thing" about windoms ... I just don't trust an antenna
which "manipulates" RF on the feedline in "beneficial" ways and has a
religious cult following ... insane quirk of mine, really. lol *Now I
don't have the room ... moved again.

If the wife had her way, we would move to Montana next to a favorite
sister and brother ... there we would have the room! lol

Regards,
JS

Hello John,

When the feed line goes to a clean environment (for example a ground
provision far from the shack feed line radiation may not be a problem,
but it isn't my favorite. *When the feed line goes directly to the
shack (and equipment), I don't want such an antenna.

When you are working NVIS on 75/80m, you don't want the vertical
component as this leads to radiation under low elevation, hence
stronger reception of ground based interference.

In case of DX, the vertical component may help you as this may result
in lower elevation of main lobe; over here we have much soil with
better then average conductivity. If I would like vertical
polarization, I prefer 100% of that, so no windom or OCF dipoles for
me.

Depending on the design, allowing vertically polarized radiation may
result in worse or better VSWR.

Regarding the color, many straight people wear it over here
(especially in summer days), so you can't judge on color only....

Regarding the balun/transformer, you need a very good one with OCF
dipoles as common mode voltage at feed point can be in the 300V range
with 100W input. just some pF *stray capacitance in a transformer will
provoke feed line radiation.

Best regards,

Wim
PA3DJSwww.tetech.nl
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Hello boys, good day for you

Is it Carolina Windom a balanced load to justify the name "balun"? We
could think in a device to transform Z and another device to block
feed line current. What do you think about it?

Miguel

Hello Miguel,

I didn't follow this topic for some days.

The two-step approach will work and you are right, "balun" is not a
good word for an OCF dipole as a "balun" can also be a center-tapped
transformer where the center is connected to the ground of the
unbalanced side (voltage type balun). This one will not suppress
common mode current in an OCF application.

What you need is a "device" that does the required impedance
transformation and accepts large common mode voltage at the high
impedance side without introducing common mode current in the feed
line.

Regarding the two-step approach, I have a simple "device" for
reception. It consists of a 1:3 (1:9 impedance ratio) ferrite auto-
transformer (no galvanic insulation). The 50 Ohms side (coaxial)
contains a three section common mode choke to avoid common mode
current in the 50 Ohms feed line.

Best regards,


Wim
PA3DJS
www.tetech.nl
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