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[TowerTalk] Multiband with the TH6DXX

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Subject: [TowerTalk] Multiband with the TH6DXX
From: (teamw)
Date: Sun, 2 Sep 2001 22:07:11 -0400
My previous post about the need to publicise simple compact antennas for the
many hams with extremely limited space spawned a number of responses.
Unfortunately only one was positive the others tended to be somewhat
unsympathetic. Even suggesting that these unfortunates should have been more
careful in the choice of an XYL, should sell out and buy a new house with
adequate space, establish an antenna farm at another location and go there
with a mobile setup etc. All based on a lack of understanding of the real
world situations that face many hams with limited funds and inadequate space
from which there is no simple practical solution except to find an antenna
which will work in their situation albeit a compromise.
Subject closed.

Here is a practical suggestion that may have some application for some
people and which worked quite well for me for the past several years.
I had a TH6DXX at about 60 ft which went through two driven elements due in
part to the east Florida coastal heat and humidity and the salt at my
location on the barrier island 300 yards from the beach. Also those little
unidentified devils that were able to transport bits of grass from the
ground to the inside of the traps. Another  problem was the disintegration
of the white plastic parts inside the traps.
I tossed out the driven element and replaced it with 34 ft of aluminium
tubing and center fed this with 450 ohm ladder line. The result was
noticeably improved performance on 20,15 and 10 mtrs with better signal
reports on my daily reports from the European net I belong to and also an
apparently improved F/B ratio.
The bonus was that suddenly I had an antenna that also worked on all of the
other bands from 3.5 through to 24 Mhz.
On 3.5 Mhz it was mediocre very short dipole but did get out better than no
antenna - a 36 ft dipole is not too hot at this freq.
On 7 mHz it was a bit better but not as good as full size.
On 10 Mhz it was even better but still a short dipole .
On 18 Mhz it worked well as an extended double zepp with a small amount of
On 24 Mhz it worked well in certain directions as a near one wavelength with
a figure of eight pattern.
I have no idea what contribution the parasitic elements made on the extra

I had a lot of power lines and not much in the way of antenna supports
except the tower. Working the low bands was almost impossible and there
wasn't much space for adding WARC band antennas. I had a crank up tower
which had to be brought down when not in use. An inverted Vee might have
been feasible but would have been predominantly a high angle radiator and
much of its field would have been below the power lines.
The modification to the beam worked extremely well on the bands the beam was
designed for and the extra bands were a bonus which were provided at no
extra cost or effort. I used this set up for several years until I moved to
the current QTH where I have more room for full size antennas for the low
I don't offer this as a scientifically designed antenna just as something
that evolved during a situation that I had and which provided a useful if
compromise bonus for a period of time.
John AB4ET - TT8JW - A45FX - VK1QL - VK5QL - ST2QL - G3KQL

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