.... yes, I am known to reply to my own posts--far too often...

From all the current baluns I have tried, and I have tried every type I
could find, this choke/balun design is my favorite and seems to have the
lowest insertion loss of all and seems to exhibit excellent qualities of
the type desired:
http://home.datacomm.ch/hb9abx/pactor-e-choke.htm

John

"John Smith" wrote in message
...
... I should have pointed out, always, the balun has been inserted at
the antenna, and never at the transmitter end of the coax in my
previous post...

John

"John Smith" wrote in message
...
Reg:

I can comment on my recent experiments with a half-wave vertical on
10-11 meters.

A current balun (or ferrite beads on the coax) greatly reduce
feedline radiation--seems to have an overall beneficial effects on
the antennas radiation pattern--and seems to "stabilize" the
pruning/tuning of the antenna (things begin behaving in a linear and
logical way.)

Mind you, the above is only deduced/measured with a FSM, SWR bridge
(of the type which does NOT work for real measurement of swr but
rather transmitter loading) and observed/known signals from other
stations and the reports given back on my signal from these stations.

While this may be viewed as "crude" by some--it is real world in that
the effects as least "seem" real.

Or, the short form of all this is, "The Current Balun is my friend!"

John

"Reg Edwards" wrote in message
...
A choke balun is what is inserted between the transmitter end of the
antenna feedline and the transmitte tuner. Or it can be inserted at
the antenna end of the line.

Questions : How effective is it? To what extent can the percentage
unbalance current on the feedline be expected to be reduced? Has
anybody ever measured it before and after insertion?
----
Reg.

The only thing I have against them (current baluns) is
They are heavy.
and cause the antenna to droop
lowering the height of the feedpoint.
Which is a good reason to put the balun near the radio and use balanced
feedline from there to the antenna
my 3.5 cents


"John Smith" wrote in message
...
... yes, I am known to reply to my own posts--far too often...

From all the current baluns I have tried, and I have tried every type I
could find, this choke/balun design is my favorite and seems to have the
lowest insertion loss of all and seems to exhibit excellent qualities of
the type desired:
http://home.datacomm.ch/hb9abx/pactor-e-choke.htm

John

"John Smith" wrote in message
...
... I should have pointed out, always, the balun has been inserted at
the antenna, and never at the transmitter end of the coax in my
previous post...

John

"John Smith" wrote in message
...
Reg:

I can comment on my recent experiments with a half-wave vertical on
10-11 meters.

A current balun (or ferrite beads on the coax) greatly reduce
feedline radiation--seems to have an overall beneficial effects on
the antennas radiation pattern--and seems to "stabilize" the
pruning/tuning of the antenna (things begin behaving in a linear and
logical way.)

Mind you, the above is only deduced/measured with a FSM, SWR bridge
(of the type which does NOT work for real measurement of swr but
rather transmitter loading) and observed/known signals from other
stations and the reports given back on my signal from these stations.

While this may be viewed as "crude" by some--it is real world in that
the effects as least "seem" real.

Or, the short form of all this is, "The Current Balun is my friend!"

John

"Reg Edwards" wrote in message
...
A choke balun is what is inserted between the transmitter end of the
antenna feedline and the transmitte tuner. Or it can be inserted at
the antenna end of the line.

Questions : How effective is it? To what extent can the percentage
unbalance current on the feedline be expected to be reduced? Has
anybody ever measured it before and after insertion?
----
Reg.

On Sun, 26 Jun 2005 14:19:30 -0400, "Hal Rosser"
wrote:

The only thing I have against them (current baluns) is
They are heavy.
and cause the antenna to droop
lowering the height of the feedpoint.
Which is a good reason to put the balun near the radio and use balanced
feedline from there to the antenna
my 3.5 cents


I just weighed 50 beads that are used in W2DU's balun and came up with
a whopping 4 ounces!

Yea, four ounces should cause one hell of a droop.G

73,
Danny, K6MHE

Dan Richardson k6mheatarrl wrote:
Yea, four ounces should cause one hell of a droop.G

Droop is like dB loss - it should be minimized at all costs. :-)
--
73, Cecil http://www.qsl.net/w5dxp

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Dan:
"Droop?"

Hmm, I have heard about that, brits may refer to it as "brewers droop?"
Or, maybe I am confused here...

However, problem only seems to occur when there are pints involved...
grin

John

"Dan Richardson arrl net" k6mheatdot wrote in message
...
On Sun, 26 Jun 2005 14:19:30 -0400, "Hal Rosser"
wrote:

The only thing I have against them (current baluns) is
They are heavy.
and cause the antenna to droop
lowering the height of the feedpoint.
Which is a good reason to put the balun near the radio and use
balanced
feedline from there to the antenna
my 3.5 cents


I just weighed 50 beads that are used in W2DU's balun and came up with
a whopping 4 ounces!

Yea, four ounces should cause one hell of a droop.G

73,
Danny, K6MHE

Add that 4 ounces to the weight of 50 feet of coax.
then subtract the weight of 50 feet of balanced line
that is a larger difference

"Dan Richardson arrl net" k6mheatdot wrote in message
...
On Sun, 26 Jun 2005 14:19:30 -0400, "Hal Rosser"
wrote:

The only thing I have against them (current baluns) is
They are heavy.
and cause the antenna to droop
lowering the height of the feedpoint.
Which is a good reason to put the balun near the radio and use balanced
feedline from there to the antenna
my 3.5 cents


I just weighed 50 beads that are used in W2DU's balun and came up with
a whopping 4 ounces!

Yea, four ounces should cause one hell of a droop.G

73,
Danny, K6MHE

In your original post you said:

"The only thing I have against them (current baluns) is
They are heavy.
and cause the antenna to droop lowering the height of the feedpoint."

Anyway, with say fifty pounds of tension just how much drop are you
talking about? And what difference does it make?




On Sun, 26 Jun 2005 17:11:43 -0400, "Hal Rosser"
wrote:

Add that 4 ounces to the weight of 50 feet of coax.
then subtract the weight of 50 feet of balanced line
that is a larger difference

"Dan Richardson arrl net" k6mheatdot wrote in message
.. .
On Sun, 26 Jun 2005 14:19:30 -0400, "Hal Rosser"
wrote:

The only thing I have against them (current baluns) is
They are heavy.
and cause the antenna to droop
lowering the height of the feedpoint.
Which is a good reason to put the balun near the radio and use balanced
feedline from there to the antenna
my 3.5 cents


I just weighed 50 beads that are used in W2DU's balun and came up with
a whopping 4 ounces!

Yea, four ounces should cause one hell of a droop.G

73,
Danny, K6MHE

"Dan Richardson arrl net" k6mheatdot wrote in message
...
In your original post you said:

"The only thing I have against them (current baluns) is
They are heavy.
and cause the antenna to droop lowering the height of the feedpoint."

Anyway, with say fifty pounds of tension just how much drop are you
talking about? And what difference does it make?


Apparently it makes more difference to me than it does to you.
I don't want it digging into the tree branches.
Nothing wrong with your view - its probably a better-informed view than
mine - but I'll still use balanced line and I still think baluns are too
heavy. I'm just hard-headed that way. :-)

Hal Rosser wrote:

Apparently it makes more difference to me than it does to you.
I don't want it digging into the tree branches.
Nothing wrong with your view - its probably a better-informed view than
mine - but I'll still use balanced line and I still think baluns are too
heavy. I'm just hard-headed that way. :-)


Unfortunately, using "balanced" (symmetrical) line doesn't prevent or
reduce feedline radiation. It's subject to the same effects as coax. The
only difference is where it happens. Conducted common mode current is
explained in http://eznec.com/Amateur/Articles/Baluns.pdf. As for
current induced by mutual coupling, both types of feedline will have the
same amount of induced common mode current, due to the same cause and
having the same effect.

It's not the geometry of the feedline that causes or prevents feedline
radiation.

Roy Lewallen, W7EL

Hal Rosser wrote:

"Dan Richardson arrl net" k6mheatdot wrote in message
.. .
In your original post you said:

"The only thing I have against them (current baluns) is
They are heavy.
and cause the antenna to droop lowering the height of the feedpoint."

Anyway, with say fifty pounds of tension just how much drop are you
talking about? And what difference does it make?


Apparently it makes more difference to me than it does to you.
I don't want it digging into the tree branches.

That's a fair point. The sag in a dipole supported only at the ends is
very sensitive to the suspended weight in the middle. And if the end
supports are trees, the problem can become extreme.

Nothing wrong with your view - its probably a better-informed view than
mine - but I'll still use balanced line and I still think baluns are too
heavy. I'm just hard-headed that way. :-)

If sag is a problem, don't use 300 or 450-ohm ladder line. In terms of
weight and windage, it is a very bad solution. A much more practical
solution is to make your own ultra-lightweight parallel line. The wire
can be much thinner than the main antenna, and you can use a spacing of
several inches with the absolute minimum number of ultra-lightweight
spreaders.


But more important than that, please stop calling it "balanced line".
Somehow we have got into the habit of kidding ourselves that
parallel-wire line is balanced line. It isn't!

Parallel line does NOT automatically balance itself. It will cheerfully
allow unequal currents on the two wires. That's the same as saying it
will cheerfully support an unwanted common-mode current (same magnitude
and same direction on both wires) in addition to the wanted
equal-and-opposite currents.

So parallel line will NOT be balanced line - not until you have done
something to MAKE it balanced.

The one best way to create a balanced feedline is to make the layout of
the antenna and feedline is completely symmetrical with respect to
ground - and that includes the entire run of feedline back to the shack.
Unless you have taken the trouble to do that, you WILL have common-mode
currents on the line and it WON'T be balanced. The common-mode current
may not be large enough to cause a practical problem... but don't ever
kid yourself that it isn't there.

Because it's difficult to use a choke balun with parallel-wire line, and
because of the weight problem, about the only practical place where you
can stop common-mode currents is at ground level. A choke or a
link-coupled ATU will force a minimum in the common-mode current at that
position; but a quarter-wavelength up the line towards the antenna, it
will also force a maximum in the common-mode current (and if the line is
long enough, these maxima will repeat every half-wavelength). With
parallel-wire feedline, your only defence against that problem is a
symmetrical layout.



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