On 7/28/2023 1:31 PM, Al Lorona wrote:
Please don't laugh at me; I'm a transplant from a region of the country with
essentially no lightning to a region where you have to worry about it quite a
bit.
The answer is, as KK9A said, to follow proper grounding and bonding to
the letter. N0AX's ARRL Book on the topic, to which I contributed, is
excellent. You want the Second Edition, published about a year ago. The
book also references the slide deck for my tutorial talks. Don't let
"audio" in the link fool you -- it's all about grounding and bonding in
the shack for lightning protection and to minimize RFI.
http://k9yc.com/GroundingAndAudio.pdf
On 7/28/2023 3:04 PM, Keith Trinity WE6R wrote:
> Please, PLEASE disconnect your COMPUTER from your radio(s) if lightning
> is in the area!
>
> Almost ALWAYS lightning damaged gear that comes in for repair, was hit
> _thru the comm port!_
> (lightning hits Cable/DSL lines).
This is the result of failure to follow proper grounding and bonding,
and the failure of equipment mfrs to properly bond cable shields to the
chassis at the point of entry. That failure to common to all ham mfrs,
including Elecraft. This construction error was first addressed in 1994
by a ham working in pro audio, Neil Muncy, ex-W3WJE (SK), and he called
it "The Pin One Problem," because Pin 1 of the XLR connectors used to
carry balanced audio is the shield contact. I addressed it beginning on
page 5 of this RFI tutorial, which started out life in 2007.
k9yc.com/RFI-Ham.pdf
A major contributor to that lightning damage are the MOV-based surge
protectors provide power to interconnected equipment. The MOVs short to
the green wire; the IR drop in the green wire from that current spike
raises the reference potential for equipment plugged into it, and the
difference between that and the chassis of interconnected equipment
that's grounded somewhere else fries the interconnected circuitry. We
started seeing this in pro audio systems in the early '90s, with no
antennas involved. The solution was elimination of those MOV protectors,
replacing them with series-mode units that stored surge in a monster
inductor, then discharged it slowly as a trickle after the strike had
passed.
A colleague blew out the Ethernet ports of computers in his small design
office from exactly this mechanism. Again, no antennas were involved.
73, Jim K9YC
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