On Apr 20, 12:16 pm, Jim Lux wrote:


I find that trying to prune/tune a multiwire antenna (like a fan) is an
exercise in frustration because of the strong interactions among the
elements, aggravated by the fact that most people install antennas in
places other than a vacuum. there's wind blowing (which changes the
spacing), trees, other stuff, etc.

Thats why I always spread them apart. I never stack the elements,
or have them closely spaced. I'll place them at right angles,
if only two bands.. The third band, I'll usually stick equally
between the others. If you have a coupling problem with
the third band, often just moving that leg a few feet one
way or the other will cure the problem. Once you do that,
you won't have wind problems with the higher band.
The only other type "all band" dipole I use is the "sectioned"
dipole, where you use insulators, and clips to open/short the
overall length of the dipole for other bands. But I only use those
when camping when I can only string a single wire.


So, I figure that if you get it "reasonably close", and then use an
autotuner to deal with the rest. If you want to obssess about loss in
the feedline, then put the tuner at the feedpoint.

Most of the time the loss is not a big deal. Only on the "hi Z"
bands,
where the antenna is a full wave, etc, will it be a problem. And even
then, you can still operate. I use 213 coax, so if the SWR is under
say 5:1, and I'm on a fairly low frequency, the loss is not a big
deal.
That's about my scenario on 30m, where I have no resonant elements.
Still works quite well.

Yes, the tuner costs some money, but it's a one time investment, and
makes playing with wire antennas much more pleasant and fast. Once
you've got that tuner, you can literally build decent antennas in 10
minutes with parts from the grocery store.

Maybe so, but I can do the same without a tuner too...
I don't use a tuner on the normal "resonant" bands.
A coax fed dipole is my favorite 10 min "quicky" antenna.
The only cost is coax and a bit of wire. No tuner
needed, and the system efficiency is hard to beat.
My 989c will handle open wire feeders, but I don't use them much.

If you get a tuner that has a computer interface, then you can use it to
measure the Z of the antenna, if you feel compelled to prune.

Actually, I can probably do it faster from sense of smell... :/
I find the same thing using the analysers... I can often tune
an antenna faster the old fashioned way, then using the new
fangled analysers.. I don't own an analyser myself, but I
have tried the MFJ versions that friends of mine have.
I'm too cheap to buy one, thats for sure... All it does is
verify what I can already see using the old methods.. :/
MK