----- Original Message -----
From: "Gene Fuller" <w2lu@rochester.rr.com>
To: <K7LXC@aol.com>
Sent: Sunday, February 03, 2013 5:01 PM
Subject: Re: [TowerTalk] Temporary tower/antenna question
Hi Steve -
My favorite for portable operation for some time has been a forty foot
center fed wire vertical dipole fed with 450 ohm window line. I use a
little home brew balanced tuner (floating ground "T" network with 4:1
balun at the low Z end). This provides reasonable low angle takeoff
(especially if near salt water) is fairly efficient, and is easy to pack.
I have also used it with fair success on 80 by clipping a 100 foot
extension to the top. When combined with one of the little transceivers
and switching power supplies it is easily carried in a small carryon
suitcase if you're flying. I sometimes take along one of the collapsible
fiberglass masts and tape the antenna to the mast. The length certainly
isn't critical but if you get much more than 40 feet the main lobe starts
braking up on 10 meters. If ten is of no consequence the length can be
increased to about 60 feet to better accommodate 15-40 meters.
Considerations include type of operation contemplated i.e desired takeoff
angle, type of location (salt waster, mountain top, etc), bands of
interest. Rule of thumb re length : if you want to stay away from lobe
splitting keep it less than 5/8 th's wave on highest frequency. For
useable efficiency keep it at least 40% of a half wave on the lowest
frequency (clipping extra wire on even just end for night time use is one
"workaround").
I've had a pretty good time with this approach - it's easy to implement,
travels well, works well, and is fairly inexpensive. Although a balanced
tuner with the balun at the radio side is a bit more efficient, the
commercial tuners that use a balun at the antenna side of the tuner would
probably work fairly well also.
Gene / W2LU
----- Original Message -----
From: <K7LXC@aol.com>
To: <towertalk@contesting.com>
Sent: Friday, February 01, 2013 4:36 PM
Subject: [TowerTalk] Temporary tower/antenna question
Howdy, TowerTalkians --
I'm researching temporary antenna installations (like Field Day) and
was wondering if you have some input. What did you use? How did you
erect
it? Materials? Hints and kinks?
This is with an eye towards safety and effectiveness. I don't need
real specifics (like what antenna to use) but general thoughts and
considerations. Tnx for any input.
Cheers,
Steve K7LXC
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