"Jan Panteltje" wrote in message
news:1128121187.cd7b4cc1bdd8545b9d41c7ec94da4169@t eranews...
On a sunny day (Fri, 30 Sep 2005 15:26:20 -0500) it happened "Kevin,
WB5RUE"
wrote in
:
I just did read this:
http://www.polyphaser.com/ppc_TD1016.aspx
and it gives me some good ideas how to do things.

A direct strike will vaporize that little box. Not to dis polyphaser,
they
make some excellent products all up and down the line but those discharge
tubes WILL NOT protect against a direct strike. NONE, NADA.

Kevin, WB5RUE
I am aware of that Kevin, but it has some great ideas how to make good
earth
at the mast, and also it reminded me to somehow connect the coax screen to
the
mast, now it is isolated.
Probably the GPA base will flash over, but better if the electrons go to
ground then if these go down the coax (outside) even if it is
disconnected.
There are some other good suggestions on that site too...

In any case I will try to get my lightning detector working, and
disconnect
if it detects anything.

As for the lightning detection electronics - I am now planning on the
tuned
ferrite rod, followed by a FET then by a PIC microcontroller... the
small ones I have can replace a LOT of logic for pulse detection and
processing, and have a comparator build in to detect precise voltage
levels.
PIC12F629 I have here a box full of...
The advantage is that I can re-program the thing once I get a better idea
what the lighting signals look like (so less false alarm).
The price of these PICs is about a dollar :-) Only 8 pins DIL, internal
oscillator, few micro amps power, hardly any other components needed,
except for a beeper of sorts as alarm.


It doesn't matter really how good your ground system is. If your antenna
takes a direct strike and 99.999% of the energy goes into the ground you
will still get several thousand volts (or hundreds of thousands of volts)
coming down your coax. Unless you are willing to spend thousands of dollars
on an active lightning protection system your only protection is to
disconnect.

Kevin, WB5RUE



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