All interesting stuff. Oh, and Hans, I was reporting not having seen
CBs damaged on the tuna boats by lightning. It could have easily been
due to having other stuff on board like tall steel masts etc (high
mounted RDF antennas) or whatever that protected the CB radios. Never
saw a marine band VHF with lightning damage either. Ditto Marine band or
ham band HF radios too. RDFs frequently got their goniometers fried.
These tuna boats went places like American Samoa, Australia, Guam, and
so forth so the likelihood of not encountering lightning at sea would be
extremely remote.
I got an email back from my senior scientist/ham friend who worked with
me when the "all solid state stuff aboard fried" incident happened. He
was not assigned to that restoration but recalls the report when our
outfit took the job and helped me with the time frame. It was no later
than early April 1980 (not intending humor relating to early April,
April Fools Day) and could have been as early as 1979 but no sooner.
Too bad this wasn't an event of more general interest as it could have
been documented in a news paper. We waterfront electronics types chatted
about it among ourselves but it wasn't on the 6 o'clock news.
I suspect your CB good buddies had antennas for their CB radios that
were the highest conductors around.
Interestingly we just had a T-storm fire up and I double checked to see
that my coax was not attached to the transceiver but instead is at the
in-floor ground rod.
Patrick
On 4/22/2015 4:06 AM, Roger (K8RI) on TT wrote:
An EMP, is a magnetic pulse of high intensity, but of little duration.
With semiconductors, it's the voltage generated by the magnetic pulse
tat causes the semiconductors to fail. Semiconductor junctions are
frail, or fragile if you will. Just handling them can cause elaborate
junctions to fail without the user feeling a thing.
I worked in the Semiconductor industry for over 26 years, then earned
a Bachelors degree in CS, started on my masters, when a good job put
me back to earning a decent wage although as a GA in CS I had a higher
pay than many out in the work force. Then worked with computers for
another 7 years and retired as a Computer Systems project manager.
We often had computers near ultra strong magnetic fields which did not
bother the computers although I can't say the same for the Hard Drives.
I wasn't there, but based on my background, I can see an EMP causing
the failure of circuits without the user even being aware. OTOH in
the cases sited, it was most likely induced voltage causing sensitive
devices to fail. EMPs are a very complex phenomena
Lightening EMP: https://en.wikipedia.org/wiki/Electromagnetic_pulse
The initial pulse would cause relatively high voltages with each
successive cycle causing less.
https://en.wikipedia.org/wiki/Electromagnetic_pulseAgain the pulse can
generate extremely high voltages that can reach 50,000 volts per
meter, but over a short range unlike the nuclear generated EMP.
I believe lightening can generate a more localized EMP in the E2 class
more powerful than a nuclear device...discounting the possibility of
devices that can produce super EMTs.
73
Roger (K8RI)
On 4/21/2015 11:11 PM, Hans Hammarquist via TowerTalk wrote:
Patrick,
You must be a lucky guy or be living in a no or low lightning zone. I
can't count the number of CB radios my friends (I never owned a CB
radio for some reason) had to repair/replace due to indirect
lightning strikes and in a few cases direct hit on the CB antennas. I
also have a few SWR bridges where the reflect diode burnt out from
lightning induced power.
Hans - N2JFS
-----Original Message-----
From: Patrick Greenlee <patrick_g@windstream.net>
To: towertalk <towertalk@contesting.com>
Sent: Sun, Apr 19, 2015 10:15 pm
Subject: Re: [TowerTalk] Fwd: Near Field Lightning Damage
Bill, in so doing you would be just as wrong as Hans. Re the CB
comment. To
my knowledge we never replaced a CB for lighting causes.
Patrick NJ5G
On
4/19/2015 7:33 PM, Bill Aycock wrote:
Hans is right, if a little too gentle.
I would have called the tale
"manufactured" on "Invented" rather than
"Anecdotal".
Bill--W4BSG
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