[UK-CONTEST] Wire antennas slung over trees

[G4FNL]

Andy

I have launched a number of aerial supports over trees with a local
University radio club. We use polypropylene rope (cheap stuff) but it will
need replacing every few years. It's approx 6mm diameter. (Obviously, the
gauge depends on what you're planning to support). We've got a 265ft doublet
at 60feet, an inverted L for 160m at 80ft, an 80m horizontal loop at 35ft
and a 40m dipole at 70ft. All are supported by trees. There are a few pix on
http://www.g4fnl.co.uk/ (go to University radio club page). Not very clear,
but you'll get an idea of the heights of the trees. (the big trees are
approx 90ft high)

I have used a standard ?10 approx catapult + standard nylon fishing line and
teardrop-shaped 2 - 3 oz lead weights. I have managed to launch these
weights, with 40lb nylon line over 90ft trees, provided that the wind is
low, and also provided that the trees aren't in bud. The catapult is
surprisingly accurate, and certainly goes further than simply throwing a
weight over a tree. I have heard of people using a bow and arrow - but I've
no experience of it. I have also seen the adverts on QRZ.COM for the
American version of this catapult idea - but it seems very expensive for
what it is.

Once the fishing line is over the tree, I add slightly thicker gauge line -
and pull that through. Finally, I attach the thicker support rope (the 6mm
polypropylene stuff) and pull that over the tree. It sometimes gets
snagged - depends on the tree - but it does eventually work, and I can
recommend it.

As for wire, again, I am a cheapskate. I have used whatever I could acquire.
Usually something that's quite heavy duty (I can't remember the actual
size - but it's something like 32/0.2mm strands of copper wire - standard
stuff that you could get from an electrical supplier. You don't want it too
thin 'cos it will stretch, nor too thick, as it may break the branches.
IMHO, black wire is often best for discretion. However, for certain
locations, I have used thin white plastic coated (7/0.2mm) wire at home
(over the front garden), which looks less obvious.

Hope it helps :)

73 Graham G4FNL







-----Original Message-----
From: uk-contest-bounces at contesting.com
[mailto:uk-contest-bounces at contesting.com]On Behalf Of Andy Swiffin
Sent: 04 March 2008 10:25
To: uk-contest at contesting.com
Subject: [UK-CONTEST] Wire antennas slung over trees


Sorry, slightly OT, but it will be used (almost) exclusively for contests
:-)

My forthcoming new QTH  has some goodly high trees which look like they
would make excellent aerial supports.  I know some of you utilise these
natural masts too.   What kind of wire do you use - does it have to be
plastic insulated?  What gauge, solid or stranded?  What cunning techniques
did you use to get it up there (I saw Fred Dibnah on the telly using a bow
and arrow to get a line over a tree- goodness knows what for tho').   Is
there a consensus on the colour of plastic wire which is least visible?

Sorry, I know these are not really contesting, but  I know that some of you
here have done this and with the right answers I will be a lot more QRV in
future contests :-)

73
Andy
gm8oeg


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