Off-Center Fed (OCF) Dipoles for 160-10, suggestions?

[vt...@hotmail.com]

I was reading in the ARRL Antenna Book about off-center-fed (OCF)
dipoles, and it looks like such a dipole should fit right in around
here.

I have enough space to put up a half wave dipole for 160 (about
250-260 feet or so). I'd like to be able to use that antenna for all
bands 160 through 10.

I'll only be able to get it about 40 feet up in the air.

The shack is about a third of the way across the yard, hence my
thoughts on the OCF antenna.

My options are:

1. Center fed dipole, open wire feeders. Feeders will not be able to
run at right angles to the antenna for very far (maybe 20-25 feet,
tops), then they'll have to run more or less parallel with the antenna
until they go into the shack and hook up to the Johnson Matchbox type
antenna tuner..

2. Center fed dipole, open wire feeders, SGC-type remote antenna
coupler (probably the SG-230 unless you all have a better suggestion).
Antenna coupler mounts at ground level inside a weatherproof
enclosure, directly under the center of the antenna. Feeders run
about 30 feet from the center of the antenna to the top of the
enclosure. Coax and 12v power for the coupler runs underground to the
shack.

3. OCF dipole, open wire feeders. The feed point will be quite close
to being directly above entry point to the shack, so the feeders can
almost run at right angles to the antenna until they enter the shack
and connect to the Matchbox type antenna tuner.

Which of these options is likely to give me the best performance with
minimum "RF in the shack" on 160 through 10?

RF in the shack is an important consideration because there are about
8 computers running aorund here including two commercial websites.

The radio in use will be an Icom IC-735 running barefoot. There are
no plans to increase power output.

Thanks for any advice...

Eric WA1RKT

[rb]

You'll probably have better luck in avoiding stray RFI floating around if
you use the center fed dipole. You can work it on all bands, just as you
can with the off center feds.

Can you tension the antenna enough to minimze sag? You may find, with the
length you're going to be running, that center sag is a problem. May
require a center support. Use fairly heavy gauge wire and put a good strain
insulator in the center and see how it does, first.

[Bill & Suzie Whatley]

You don't mention what power level you will be supplying to the antenna
system but the center fed with buried coax from the tuner to the shack will
minimize the rf coupling from the feed lines to the shack.

With only 30 feet or so to the horizontal dipole elements, you will
probably have some problem with higher power levels unless you have built
the shack with RF shielding in the operating location.

On any of the above configurations it is important that you provide
good DC and RF grounding to the operating location.

73
WA5VRL

[vt...@hotmail.com]

On Sun, 21 Oct 2001 10:55:34 GMT, "Bill & Suzie Whatley"
<spu...@home.com> wrote:

> You don't mention what power level you will be supplying to the antenna
>system but the center fed with buried coax from the tuner to the shack will
>minimize the rf coupling from the feed lines to the shack.

Good morning, Bill.

I'll be running the IC-735 barefoot, about 100 watts. There are no
plans to increase that.

Eric