On Jun 25, 8:51*am, Eskay wrote:
On Sat, 25 Jun 2011 03:59:55 -0700 (PDT), dave wrote:
On Jun 24, 6:16*pm, "Sal M. Onella" wrote:
I've participated in Field Day every year since 1993, when I was first
licensed. *Because I had a big 2m beam, I worked that band
aggressively, sometimes making the most QSOs. Unfortunately we lost
our hilltop FD site in 2009 and the 2m production "down low" was
disappointing in '09 and '10.

This year some youngsters want to work 2m, so I'm moving to HF, 20m
being the most promising, I think. *With the help of EZNEC (evaluation
version), I modeled a promising 20m dipole at 30'. It's almost exactly
75 ohms resistive at the freqs I want to use and I'm going to feed it
with RG-6, 0.7 dB/100 feet. My radio has an internal tuner to match
the 75-ohm cable, if I need it.

I'll report the results.

"Sal"
KD6VKW ("Vicious Killer Weasel")

wow, it takes eznec to model a dipole for field day now? *not that
many years ago i ran a competition at field day... given a hunk of
coax(with one connector installed), a roll of wire, and some random
pieces of rope, cut a 10m dipole, get it up in the air, and make a
contact. *no eznec, a tape measure if you really wanted it, and who
knows what the coax was.

You take all the fun out of a guy's efforts.

Yeah, kinda, but that's all right. I already have four working
dipoles up at home, each produced much as Dave describes; 40, 20, 20,
10.

I was seeking optimization and I got it. Example: My TS-870
electronic display lights up five little dots for a 1.5:1 SWR. As
installed, the new antenna gave me only three little dots -- most of
it probably right at the back of the radio in the transition to 75
ohms. I am very, very pleased with the results.

20m was lit up like a Christmas tree all day and into the night.
While operating 100W, I logged a new QSO every two to five minutes.
(I'm nobody's idea of a contester.) Surprise -- broke a few pileups.

I oriented the antenna for max toward 060 degrees True, the bulk of
North America from San Diego. Putting up three guyed 30-foot poles
was quite the adventure but it all worked. No blood loss, one
blister. :-)

"Sal"

PS: TS-870 reported an untuned 3:1 SWR on 15m, which the tuner
handled easily. Many QSOs on 15m.

On 6/27/2011 12:44 AM, Sal M. Onella wrote:

I was seeking optimization and I got it. Example: My TS-870
electronic display lights up five little dots for a 1.5:1 SWR. As
installed, the new antenna gave me only three little dots -- most of
it probably right at the back of the radio in the transition to 75
ohms. I am very, very pleased with the results.

The fun part of antenna modeling, at least for me, is seeing how close
the real thing meets the design. We put up an antenna for FD, an 80
meter cut for the cw portion of the band, and hit it on the first try.

As for folks tuning up rain gutters and wire salvaged from an old
toaster, then making an antenna out of it, that's fun too, but the final
result isn't likely to be optimum.

- 73 de Mike N3LI -

On Mon, 27 Jun 2011 09:33:23 -0400, Mike Coslo wrote:

On 6/27/2011 12:44 AM, Sal M. Onella wrote:

I was seeking optimization and I got it. Example: My TS-870
electronic display lights up five little dots for a 1.5:1 SWR. As
installed, the new antenna gave me only three little dots -- most of
it probably right at the back of the radio in the transition to 75
ohms. I am very, very pleased with the results.

The fun part of antenna modeling, at least for me, is seeing how close
the real thing meets the design. We put up an antenna for FD, an 80
meter cut for the cw portion of the band, and hit it on the first try.

As for folks tuning up rain gutters and wire salvaged from an old
toaster, then making an antenna out of it, that's fun too, but the final
result isn't likely to be optimum.

- 73 de Mike N3LI -

I use EZNEC 5 nearly every day. It saves me time & money. I can
minimize my physical work as well. At 71 years old that is getting
more important every day. Last week I took down my Fan of dipoles and
put up a 40m half wave in series with an 80 meter half wave, fed at
33% from one end. The wire was handy and so was the room. What a waste
and in 90 degree + weather too. If I had modelled it first, I would
have done it. Hard to feed everywhere and the low activity seem to
endorse the computed patterns.

I ran an inverted Vee through EZ5 with 43 foot wires on each side and
it looked as good as anything on 40 & 80M and was easy to tune about
anywhere. The testing has supported that the 30M and up patterns are
not nearly as useful as the corresponding dipoles, but it does work
everywhere. I got the 43 foot wires by simply folding the excess from
an 80M dipole and taping them. Nothing permanent, no $ spent. I will
likely keep this for 40 & 80. Probably back to adding in a couple of
dipoles for 30 & 17 in a fan configuration while I consider my first
venture into my first Quad effort.

20-15-10 are covered with an A3S Cushcraft at 60 feet. I don't
understand it, but it works good.

On Jun 27, 6:33*am, Mike Coslo wrote:


As for folks tuning up rain gutters and wire salvaged from an old
toaster, then making an antenna out of it, that's fun too, but the final
result isn't likely to be optimum.



Yes!

I know I've told this story here before, but ...

My first HF antenna was a 10m vertical sleeve dipole. It was mounted
only a few feet above ground. With a tuner,
I matched 15m but not 20m. I knew I needed more metal on at least one
element, so I grabbed a clip lead and a hunk of wire and headed
outside. Near the antenna, I almost tripped over an extension ladder
laying on the ground. This is a sign, I thought. I tossed the wire
and dragged the ladder over to the dipole and clipped it onto the
lower element.

Back inside, I tuned up nicely on 20m and answered a CQ. Had a nice
chat with a fellow in Hawaii; five-by copy both ways.

Some wag in this group suggested "ladder line" might improve the
setup. Good one.

"Sal"