[UK-CONTEST] 'Remote' radials...

[Mike Farmer]

----- Original Message ----- 
From: "David, G3YYD" <g3yyd at btinternet.com>
To: <uk-contest at contesting.com>
Sent: Tuesday, June 16, 2009 5:54 PM
Subject: Re: [UK-CONTEST] 'Remote' radials...


Ah the old chicken wire trick.   Be very careful - the following story is
true.   When working at a High Power Military HF Tx station we started
getting TVI reports from residents in about a quarter mile radius of a local
Pub (name available if required!!! real ale was the main stock and it was
very well keep!)  In those good old days we had a thing called the Post
Office who did TVI investigations.  First we had to shut off all the txers
(remember - HF was the only long range communications and we had a war going
on in YB land - so our bosses were not happy)  It took about 2 days to
establish that the circuit to ZC4 was the culprit and, guess what, it was
also the closest ae to the Pub.  After swapping circuits and aes it was
established that the TVI was the same whatever freq we used on that ae
(Rombic at (I think)100ft).   Anyway the nice man (by this time it was
acually MEN) from the post office cleared our equipment and after a bit of
time established that the TVI was the result of dissimilar metal used in
chicken wire and the newly built chicken pen in the pubs back yard was
condemed - result no TVI.

Tx powers were somewhat greater than our licence (by about +21db ish) and
the closest ae mast supporting the rombic was less than 50 yards from the
pub!

Mike
G3VAO

> My suggestion for a temporary ground screen is to use chicken wire
> (galvanised steel netting) and just roll it out and peg it down with
> some bricks/pegs. At the end of the contest roll it up and store it for
> the next one. The loss in the zinc coating is very small as each strand
> has a very low current due to the number of strands in parallel. Do not
> leave it down as the zinc disappears very quickly and then the steel
> soon rusts out.
>
> Have fun
>
> David G3YYD
>
>
>
>