[TowerTalk] Fwd: Near Field Lightning Damage

[Bill Aycock]

Hans is right, if a little too gentle. I would have called the tale
"manufactured" on "Invented" rather than "Anecdotal".
Bill--W4BSG

-----Original Message----- 
From: Hans Hammarquist via TowerTalk
Sent: Sunday, April 19, 2015 2:44 PM
To: towertalk at contesting.com
Subject: [TowerTalk] Fwd: Near Field Lightning Damage

This sounds very anecdotal. Yes, a near strike lightning may take out CB 
radios etc but that it took out digital watches make me suspicious. The are 
usually metal encapsulated and very immune to external field. I believe a 
EMP strong enough to take out a watch also will take out the person carrying 
that watch.


Depending on the grid size, a Faraday cage is useful for the EM from a 
lightning as the "M" will introduce back EMF in the cage which will 
neutralize the "M".


I hope the "falme" will not be too long,


Hans - N2JFS



-----Original Message-----
From: Patrick Greenlee <patrick_g at windstream.net>
To: towertalk <towertalk at contesting.com>
Sent: Sat, Apr 18, 2015 10:18 pm
Subject: Re: [TowerTalk] Near Field Lightning Damage


Back in the 80's a tuna boat pulled into San Diego with every device on
board
containing a semi-conductor inoperative.  CB radio, Marine VHF,
SSB, SONAR,
RADAR, VHS tape player, SatNav LORAN, and on and on...  All
the crew members
wore digital watches which were all totally dead.

One near miss by a large
lightning stroke took out everything with solid
state semiconductor junctions.
The good news was they didn't have a
spotter chopper aloft at the time
dependent on the aircraft beacon band
transmitter on board to find the boat
(helipad is the roof of the pilot
house.)  We theorized it was the EMP that
ate everything as there was no
evidence that the bolt hit the boat.

Later
when asked what could be done to provide an immune backup comm
radio we told
them a mu metal box.  A Faraday cage wouldn't stop the
magnetic pulse.

Just
a thought in case there are any serious preppers in our midst.

Patrick
NJ5G
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