PA0SE wrote:
It all goes to show how important the insulation of the aerial at LF is. It has
been said and written before over and over again but
it seems that an experience like I had is needed to really burn it in!
Agreed. I have had several flash-overs, including setting fire to a
plastic drain pipe which I had assumed was made of an insulating
material (brand new conservatory - not a popular thing to do!). It is
possible with an MF antenna to run the wire over a tree branch, but
not at LF. Even coming close to a leaf can cause sparks, smoke
and flames.
The problem is so bad that the (UK) Admiralty Handbook of 1926
(highly recommended for practical LF work) specifies a maximum
current, above which the corona discharge at the end of the
antenna dissipates any additional power! This is higher power than
we run, but not a lot.
So good insulation is vital, not only for best efficiency, but also for
saftey.
Mike, G3XDV (IO91VT)
http://www.dennison.demon.co.uk/activity.htm
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