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.