Hi to all,

Until now, I used a 4:1 Van Gorden Balun with an OCF dipole and of
course a coax line to the tuner. I am now trying a 450 Window ladder
line. For now, the antenna is still connected to the balun, but I
removed the coax from it, and I use the balanced line connector of my
MFJ-949E antenna tuner (a 4:1 balun is in that tuner).

My question: Should I remove the old balun or may I keep it, i.e. does
it has any influence even if the coax is removed?

I find it convenient since the balun is a good holder for the
antenna's two branches.

73 de Pierre VE2PID

Pierre,
If you don't remove that 'old' balun, then you don't have a 4:1
conversion anymore, but with 'both' baluns connected, it's more on the
order of an 8:1 conversion. Is that 'bad'? That depends on the
antenna's impedance and the feed line's impedance, but in general, I
would think that it wouldn't exactly be the 'best' thing you could
do. Removing the 'old' balun would probably be your 'best' bet. May
make making connections a little more difficult (or at least
'different') but still the 'best' solution.
Then again, before doing that "out with the old" thingy, try it and
see what the results are with both baluns in-line. Results 'better'
with or without the old balun still in line? Hmm, if I had to
'guess', I'd have to say removing the old balun would probably be your
best bet. At the very least, it means a little less weight hanging on
the antenna, one less 'point of loss' in the whole thing...
- 'Doc

(May not be the 'best' answer in the world, but it's sure a nice
"CYA"... ain't it?)

.... Uhh. May have mis-read your post. If that old balun is only
being used as a center insulator, not 'in-line' with the ladder-line,
then while it will still be providing some sort of 'impedance bump'
because it's too close to the ladder-line, it shouldn't be doing any
impedance transforming (the 4:1 thingy to an 8:1 thingy).
Objectionable? Beats me, but probably, too many "depends" in that for
a good guess.
- 'Doc

PS - Leaving it-line, but not really doing anything, DOES open the
field for all kinds of 'reasons why it's there' when explaining the
set up to an interested observer! Can you imagine the B.S. you could
invent for that??

ve2pid wrote:
My question: Should I remove the old balun or may I keep it, i.e. does
it has any influence even if the coax is removed?

It is unclear where you have connected your ladder-
line at the antenna end. Is it connected through the
coax connector or does it bypass the balun and connect
directly to the antenna wire, i.e. are you trying to
use the old balun as your center insulator?
--
73, Cecil http://www.w5dxp.com

On 24 avr, 13:16, Cecil Moore wrote:
...does it bypass the balun and connect directly to the antenna wire, i.e. are you trying to
use the old balun as your center insulator?

This is what I intended to do, using the 'eyelets' on the balun to
hold each leg and to connect the ladder line to them. Purely a
mechanical solution.

But since there is a 0 ohms (DC) resistance between the two posts on
the balun, I am concerned abour adverse effects.

ve2pid wrote:
On 24 avr, 13:16, Cecil Moore wrote:
...does it bypass the balun and connect directly to the antenna wire, i.e. are you trying to
use the old balun as your center insulator?

This is what I intended to do, using the 'eyelets' on the balun to
hold each leg and to connect the ladder line to them. Purely a
mechanical solution.

But since there is a 0 ohms (DC) resistance between the two posts on
the balun, I am concerned about adverse effects.

You need to measure those impedances at the frequencies of
interest. If the antenna feedpoint impedance is much, much
lower than the impedance looking back into the old balun,
you don't have anything to worry about. You can determine
those impedances with a lot of time and effort. Or you can
remove the balun and install an insulator. Personally, I
would install the free insulator out of my junk box. :-)
--
73, Cecil http://www.w5dxp.com

ve2pid wrote:
Hi to all,

Until now, I used a 4:1 Van Gorden Balun with an OCF dipole and of
course a coax line to the tuner. I am now trying a 450 Window ladder
line. For now, the antenna is still connected to the balun, but I
removed the coax from it, and I use the balanced line connector of my
MFJ-949E antenna tuner (a 4:1 balun is in that tuner).

My question: Should I remove the old balun or may I keep it, i.e. does
it has any influence even if the coax is removed?

I find it convenient since the balun is a good holder for the
antenna's two branches.
============================
Although this tread is ongoing for some time I respond to the original
posting.

If an Off Centre Fed Dipole is directly connected to a twin wire feeder
,be it ladder line or 300 or 450 Ohms twin feeder ( please note I do
not use the wording : balanced feeder) the current /voltage in the 2
wires at any point on the feeder will not be the same in magnitude and
differ 180 degrees in phase ,hence IMHO the feeder will radiate, which
should be avoided

If a symmetrical dipole is used there is a reasonable chance that the
feeder will NOT radiate and if that indeed is the case you can call the
feeder balanced. This can be checked for example by placing a (split)
toroid type of RF current sensor around the twin feeder (differential
current measurement).

So it makes no sense to connect an OCF Dipole directly to a twin feeder .

Frank GM0CSZ / KN6WH

Highland Ham wrote:
So it makes no sense to connect an OCF Dipole directly to a twin feeder .

So exactly to what feedline does it make sense to
connect an OCF Dipole?
--
73, Cecil http://www.w5dxp.com

Highland Ham wrote:
So it makes no sense to connect an OCF Dipole directly to a twin feeder .

Followed by Cecil Moore writing :
So exactly to what feedline does it make sense to
connect an OCF Dipole?
========================================
To coax via a (voltage)balun (usually 4:1 )
The balun being either a ferrite bar or a toroid , wound with 1 bi-filar
winding eg a 2 to 1 (auto)transformer resulting in 4:1 impedance
transformation.

Frank GM0CSZ / KN6WH

ve2pid wrote:

This is what I intended to do, using the 'eyelets' on the balun to
hold each leg and to connect the ladder line to them. Purely a
mechanical solution.

But since there is a 0 ohms (DC) resistance between the two posts on
the balun, I am concerned abour adverse effects.

Open the box, snip the wire.


Craig 'Lumpy' Lemke

www.n0eq.com