Using one of those tuners is very simple. (mostly)

Assuming you are using ladder or window line,(not only a good
assumption, but a good idea) put up as much wire as high as you can.

The "mostly" part is that you don't want the wires to be 1/4 wavelength
total on any of the bands you are going to operate. I think the MFJ
manuals point out some lengths you don't want to use.

All this is to say that if you can put say 96 feet of wire in the air,
that is what you put up. Such an antenna will work a treat on 40 and up,
decently on 80 meters, and almost so-so on 160.

You are ready. Get a couple buds, your slingshot or favorite method of
launching fishing line into the air, and put up that dipole. Run the
window line to the house, avoiding running it too near to metal objects,
say keep it around 4 inches away. Connect it to the balanced line input
on the tuner, go coax to the rig, and there you have it. Make sure you
do the grounding thing correctly, but that's another subject.
======================
Whatever the length of the dipole ,ensure the the length of 1 half of
the dipole + the length of the 'window feeder' is approx 1 quarter
wavelength of 160m . This will result is a reasonably low impedance at
the matching unit (tuner) , which that unit will happily accept.

Frank GM0CSZ / KN6WH

James barrett wrote:
Hi, I don't understand how you can add elements to an existing antenna
and have it still work on the band it was originally made for. Do you
still need a tuner? Or do you remove the 20m elements to transmit on
10m?

The RF source energy will follow the path of least
impedance. If we have dipole elements for 40m, 30m,
and 20m on the same antenna, when we are on 30m, for
instance, the 30m dipole has a low impedance while
the 40m and 20m dipoles both have high impedances
to the 10.125 MHz source signal. This configuration
can function without a tuner.
--
73, Cecil http://www.w5dxp.com

James barrett wrote:
I think I might get away with drilling two holes in the wall
and putting in connectors, then attach the ladder line to the
connectors. On the other side of the wall.... would I still want to
use ladder line to continue on into the tuner?

Some people use side-by-side runs of coax from the tuner
to the outside of the house. The center conductors of the
two runs of coax are used for the parallel lines. The
braids of the coax runs are tied together and grounded.
That alleviates any exposure to bare parallel wires.

Parallel side-by-side runs of 50 ohm coax have a Z0
of 100 ohms. Z0=150 ohms for side-by-side runs
of 75 ohm coax. For low power, side-by-side runs of
RG-62 has a Z0 of 186 ohms.
--
73, Cecil http://www.w5dxp.com

On Nov 27, 1:40 pm, Cecil Moore wrote:
James barrett wrote:
Hi, I don't understand how you can add elements to an existing antenna
and have it still work on the band it was originally made for. Do you
still need a tuner? Or do you remove the 20m elements to transmit on
10m?

The RF source energy will follow the path of least
impedance. If we have dipole elements for 40m, 30m,
and 20m on the same antenna, when we are on 30m, for
instance, the 30m dipole has a low impedance while
the 40m and 20m dipoles both have high impedances
to the 10.125 MHz source signal. This configuration
can function without a tuner.
--
73, Cecil http://www.w5dxp.com

OH, I think I understand... is that what I have heard described as a
spider web antenna.. the elements go off in different directions from
center?

jim

Richard Clark wrote:
James barrett wrote:
Why is the twin lead consideres less
lossy than coax?

All loss is in the bulk of the conductor. When comparing the two,
twin lead usually has more bulk = less loss.

The Z0 of the feedline has a lot to do with the I^2*R
losses in the line, one of the main sources of feedline
loss. Ifor = Vfor/Z0, so the higher the Z0, the lower
the current.

Coax has Z0s less than 100. Parallel lines usually have
Z0s greater than 100. That's a major reason that parallel
lines have lower losses.

It is also easier to build parallel lines with lots of
air dielectric, thus reducing dielectric losses.
--
73, Cecil http://www.w5dxp.com

Michael Coslo wrote:
James barrett wrote:
Cecil, I love your no tuner ladder line idea. I think someday I'll try
that when I have more experience with feed lines and antennas.

My xyl won't let me put one of those in - says it's visually challenged.

That was my problem in CA which I solved in 1986 by
moving to AZ and leaving the XYL behind. :-)
--
73, Cecil http://www.w5dxp.com

James barrett wrote:
OH, I think I understand... is that what I have heard described as a
spider web antenna.. the elements go off in different directions from
center?

This type of multi-band dipole antenna is called a "fan dipole".
I just did a Google search for "spider web antenna" and that
looks to be something else.
--
73, Cecil http://www.w5dxp.com

James barrett wrote:

Hi, I like the article. One question about feed lines. If coax is 50
ohms and twin lead has 300 ohms. Why is the twin lead consideres less
lossy than coax? I had thought that higher ohms meant higher impedance
and I thought higher impedance means higher loss. Obviously I have not
read the chapter on transmission lines yet ;-), so I may have that all
wrong.

Yes, you do. If a line is terminated in a load equal to its
characteristic impedance, the current along the line is sqrt(P/Z0) where
P is the power and Z0 is the line's characteristic impedance. You can
see from this that for a given power, the current is less if Z0 is
greater. From HF through UHF, the loss in a transmission line is
predominantly due to the resistance of the conductors, resulting in loss
proportional to I^2 * R, where R is the RF resistivity of the conductors
including skin effect. So when you increase Z0, it decreases current,
and therefore decreases loss, all else (such as conductor size and
material) being equal. I used a matched line for simplification, but the
lower loss also holds when the line is mismatched.

Also, in the article, I liked the part about before 1950, no one even
heard about swr, and that antennas with high swr were working just
fine.

The beginning of the hams' fetish with SWR corresponds to the
availability of inexpensive meters to measure it. Once it could easily
be measured, it gained a perceived importance way beyond reality.

But I make 2 assumptions: 1) I'm thinking, even if they didn't
know or care about swr, they still had to cut their dipoles for the
band they were transmitting on.

No, they didn't then and they don't now.

2) I still would not want to use a 10m
dipole and transmit 100 watts on 80 without at least using a tuner. Am
I correct in these assumptions?

Yes, that's correct. One thing that *has* changed between then and now
is that rigs used to incorporate a tuner (pi matching network), so often
an external tuner wasn't necessary. Today's rigs don't have this
built-in impedance matching capability.

Roy Lewallen, W7EL

On Nov 27, 2:58 pm, Cecil Moore wrote:

That was my problem in CA which I solved in 1986 by
moving to AZ and leaving the XYL behind. :-)

would that be the xxyl? ;-)

On Nov 27, 3:06 pm, Cecil Moore wrote:
James barrett wrote:
OH, I think I understand... is that what I have heard described as a
spider web antenna.. the elements go off in different directions from
center?

This type of multi-band dipole antenna is called a "fan dipole".
I just did a Google search for "spider web antenna" and that
looks to be something else.
--

I think I've been doing too much reading, and got my terms confused.
yes, I meant to say fan dipole.