[Elecraft] balanced tuner

[David Wilburn]

A very interesting read, I have a couple of questions about practical 
considerations.

The number one rule I look at all antennas with, is that all antennas 
are a compromise.  Let me know if I am getting off on the wrong foot here.

I like ladder line fed to various antennas (Horiz. Loops, Vert. Loops, 
Doublets and such) but if I have more than one antenna, then I have 
multiple sets of 450 ohm twin lead coming to the house.  As I 
understand things, I need to keep the ladder line away from metal as 
much as I can.

I have not found a way to safety ground ladder line and run it into 
the house.  After taking a lightning strike last year, I have no wish 
to have ladder line and / or balun's inside the house.

*Is there a way to properly ground that ladder line, and then run it 
into the house?
*If there is a practical way, I assume one uses a plastic box or no 
box at all?

Based on all of these practical considerations, I am left with the 
following current configuration.

K3/KAT3 -> Balun (4:1) === Ladder Line === Doublet
(In this case a http://www.k1jek.com/ 200' antenna)

The coax is about 50' long (to get to the shack in the house, I would 
love to get this shorter, working on that) and the 450 ohm ladder line 
is about 50' long.

Configuration I am working towards;
K3/KAT3 -> RF Switch -> Coax (trying to get this down to about 10') to 
box mounted on side of house (metal) -> Lightning arrestors tied to 
good ground rods -> short coax to balun mounted beside house -> 450 
ohm ladder line to antenna.

Would like to have a vertical loop and dipole or horizontal loop, fed 
with ladder line.

The antenna I have now, gets out very well, and tunes pretty well from 
160m -> 6m.  Some bands like 40m, it does not tune as well, but has 
performed well.  I have heard very little on 6m, but did work 
Portugal.  The 40m issue is supposed to be helped by reducing the 
length of coax, and lengthening the ladder line.  That makes sense, to 
reduce the resistive losses in the coax.  Understanding that this is a 
low dipole (about 40 - 50 feet) I'm wondering if changes to the 
configuration would help the antenna's ability to hear.  I'm not sure 
it hears as well as it could.

Options to improve antenna, and possibly receive
================================================
*Get current antenna higher.  With the trees that I have to use, this 
could only be about 10'.

*Drop ends of antenna to 10', and raise center higher using a 
different tree.  This has possibilities of getting the center higher 
than 60'.  I am not sure this would help receive, but it is an option.

*Go to a different balun setup 1:1 versus 4:1.

*Not sure of a practical way to get multiple ladder lines safety 
grounded and into the house.  So I do not know how to get away from 
having a balun.

Are there other practical options I am missing here?  Yes, I would 
like to have a short tower and a multi-band cubical quad.  Maybe at 
some point in the future, but not anytime soon.

David Wilburn
K4DGW



Ron D'Eau Claire wrote:
> Also, the load has a huge effect on balance. Few wire antennas for HF offer
> decently balanced loads. Unless the wires are literally wavelengths (usually
> hundreds of feet) from the earth and other objects, those objects will have
> a strong effect on the currents on each side of the antenna. The effect is
> greatest near the ends of the wires, where they typically come close to
> supports, trees, houses, etc. Unless both ends have identical surroundings,
> the antenna, and so the currents in the feedline, are unbalanced. 
> 
> Ron AC7AC
> 
> 
> -----Original Message-----
> The question is, what is good enough?  To minimize radiation from an open
> wire tuned feeder requires, I believe, that the currents in the two wires to
> be equal in magnitude and have a phase difference of 180 degrees at the
> feedpoint of the feedline.  Feeding a slanted dipole, which is certainly an
> unbalanced antenna, is it practical to build a 1:1 balun on a ferrite core
> (core type choice?) that, when placed on the output of an unbalanced tuner,
> is good enough to force the desired currents from 40m thru 10m without
> excesive losses?   Using an LC inductively coupled balanced tuner on such an
> unbalanced antenna will not produce the desired results--deliberately
> unbalancing the LC tuner by offsetting the taps on the coil will sometimes
> get close for me.
> 
> 73 Paul W5DM
> 
> 
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