[TowerTalk] Fwd: Near Field Lightning Damage

[Patrick Greenlee]

Well Hans, I was there when the vessel made port (about 1980.) Where 
were you?  I took a sabbatical from my usual employ and worked for a 
short while in field service engineering for two San Diego based firms, 
Marine Electric and Honor Marine.  I held a commercial radiotelephone 
lisc with ship's RADAR endorsement.

Being suspicious and skeptical of an anecdotal retelling of a once upon 
a time tale is a trait we share but I personally would avoid calling a 
witness to the fried equipment a liar by any means, however indirect.

Oh, and these digital watches were  not metal encapsulated on the side 
where the wearer was intended to view the readout.

Admittedly this was a one off occurrence in the collective experience of 
the waterfront electronics types I talked with about the event.  Much 
more common was to lose goniometers in RDF equipment due to antenna 
position (highest point aboard but usually not much else.

Patrick   NJ5G

On 4/19/2015 2:44 PM, Hans Hammarquist via TowerTalk wrote:
> 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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