[UK-CONTEST] Wire antennas slung over trees

[Peter Hobbs]

I've done a similar job with my Sequoias (another name for Redwoods?), 
except I had the climber tie a short fixed rope to the trunk near the top. 
This carries a substantial pulley to support the running line, which is 
deployed exactly as David has described and prevents the rope working 
against the tree, also allowing the counterweight to be placed at the tree 
end (on the "inside" section).  A couple of advantage pulleys reduce the 
range of movement of the counterwight in high winds.  Being fairly near the 
ground these are easy to service/replace.

This arrangement will last a very long time if you take note of the 
following:

*  Don't economise on the quality of the top pulley (a decent SS pulley is a 
lot cheaper than the tree-surgeon)

*  Make the sheave oversized so that the running line can be replaced 
without climbing the tree again

*  Give an occasional tug to the counterweight if there hasn't been a blow 
for a while to clear any debris in the pulleys before it becomes embedded in 
resin

*  Inspect the running line every couple of  years and replace it before the 
inevitable happens

Bare 7/029 (or equivalent) BeCu or CdCu wire is hard to beat for the wire 
itself, but is quite heavy in long lengths so a substantial log is needed 
for the counterweight!  I installed a rhombic using this material down in 
VP8 land in '62 that was reported as being still in good condition when it 
was taken down (for "green" reasons) nearly 25 years later.

Good luck to all in BERU!

73, Peter G3LET


----- Original Message ----- 
From: "David Ferrington, M0XDF" <M0XDF at Alphadene.co.uk>
To: <uk-contest at contesting.com>
Sent: Thursday, March 06, 2008 9:04 AM
Subject: Re: [UK-CONTEST] Wire antennas slung over trees


>I have 2 Redwoods in the back garden, one ~ 130ft tall and the other ~
> 100ft. I had a tree climber (tree surgeon) climb the shorter one (its
> further away) to about 6ft from the top and drop a Kevlar halyard straight
> down inside the branches, the other end he threw beyond the canopy 
> (weighted
> by a karabiner). I joined the ends (making a loop), and fitted an 
> insulator
> there. I pull the wire up the outside using the 'inside' halyard to pull 
> up,
> the 'outside' halyard is used to pull it down again if the wire breaks 
> etc.
>