[UK-CONTEST] Fishing line as support

[David G3YYD]

I have used fishing line for my wire antenna end supports for decades.

The best colour to use in my environment is green (not florescent 
green). It is difficult to see against a tree/hedge background and is 
pretty invisible against the sky. Do not buy white (translucent) as this 
shows up.

I normally use 1mm mono-filament nylon. It lasts for many years but does 
eventually break (at least 5 years). It is so cheap that replacement is 
not a problem.

I have under icy circumstances had the line melt where the line is tied 
to the copper wire. This is of course a very high voltage point and I 
think the ice covering extra loss melts the line before the water 
evaporates off. Or may be it coronas. This only happens with high power 
and carrier tune up/RTTY/CW. There are two solutions. The first is to 
use a circa 25mm diameter ring of plastic cut from plumbing out door 
plastic pipe or a thicker piece of plastic string e.g. garden twine 
between the antenna end and the line.

I find that for extra strength with heavy wire dipoles and for 
supporting the coax as well that the use of fishing braid is called for. 
This is more visible but comes in higher strength ratings than 
mono-filament. It is still less visible than rope.

The nylon mono-filament line is a great shock absorber as it is very 
stretchy. This means it can absorb shocks and so can take a higher 
strain than its rating as long as the stretch without breaking reduces 
the load on the line. I have run it over tree branches and it seems to 
take the abrasion from movement against the branch well but braid is 
better. When tightening the line I wear a leather glove on the 
tightening hand and use the ungloved hand to tie off.

I suggest you look around the web to find a good deal and buy a big reel 
as it is cheaper per metre and will last you for many years unless you 
have a huge garden and lots of wire antennas.

73 David G3YYD


On 29/09/2011 09:36, G3RAU at aol.com wrote:
>
> In a message dated 29/09/2011 00:39:12 GMT Daylight Time,
> g4lmw at btconnect.com writes:
>
> My  question is - what breaking strain would be advisable?
>
>
>
> You could work out the total broadside cross sectional area of the antenna,
>   estimate your greatest wind gust speed (not average) at the height of the
> antenna, do the maths and you have the first part of the answer.
> Secondly the tighter you pull the ant the greater the stress; the Arrl ant
> book looks at sag tensions in horizontal wires.
> Thirdly is there a balun or anything that could introduce a bouncing up and
>   down effect in high wind? More complicated to evaluate because you need to
> know  the stretch characteristics of the support line.
> The practical answers which  have been suggested, although  empirical,
> sound very sensible to me, and save hours in the text books!
> There is an old Indian trick (remember the  Lone Ranger?) of making a  loop
> at the end and dangling it in a U shape say 24 inches long.   Across the
> top of the loop you tie a short piece of you support material but  half cut
> through.  That way when the snow/ice arrives, and weighs down the  ant, the
> weak link snaps, the ant drops a foot suddenly and all the snow  falls off.
> The ant is still up there but a foot lower.
> Have fun
> 73 Derek G3RAU
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