Actually, I took a direct hit on my 40M yagi some 3 years ago, about 200 feet
from the house and 100 feet in the air. Thanks to disconnection, I lost
nothing on the radio side in the shack. Unfortunately, my wired Ethernet
network connections made a good antenna, and the induced EMP killed both
computers. Aside from them, we lost only the stuff on the tower, and a
telephone answering machine. I'm not sure that additional measures would do
much to improve on this.
73, Pete N4ZR
At 09:55 AM 12/8/2006, Phil Camera wrote:
>Even though a second floor shack is not optimum, installing a well designed
>grounding system is not out of the realm of possibilities. Polyphaser has a
>good technical article discussing exactly this problem.
>In summary a well designed grounding system consists of the following elements:
>1. Tower or mast ground
>3. Lightning arrestors
>4. Shack ground
>5. Service entrance ground
>All five must be tied together, outside, for it all to work. Leave out any
>part, and Mother Nature has an entry route. Yes, being upstairs from your SPG
>is a problem but what you'd need to do is install the lowest
>resistance/impedance ground from your shack to the rod. The best would be
>copper strip a number of inches wide. With everything listed connected
>together, when your system gets that energy surge from a strike or nearby
>strike (up to a mile away can induce enough current to fry electronics) then
>everything rises in voltage together and there is no potential difference
>between grounds which is what zaps your electronics.
>Simple disconnetion outside can work, as far as eliminating the lightning
>arrestor part of the above list but you'd then still need to take care of all
>the other listed items. A surge via your power lines can also zap your
>electronics even if the coax is disconnected. The best would be to totally
>disconnect your rig and put it in the closet but I'd doubt you'd do it every
>time and it only takes one time to get bummed out. Worst case you might have
>lightning getting into the house and that can be bad also.
>-------------- Original message --------------
>From: Pete Smith <firstname.lastname@example.org>
>> At 09:18 AM 12/8/2006, Phil Camera wrote:
>> >"Something to bear in mind is that, in general, most jurisdictions don't
>> enforcing the NEC for amateur radio antennas"
>> >Which actually is too bad because these guidelines are exactly the measures
>> should do for a properly installed safety & lightning prevention grounding
>> system. And every single measure must be in place or else you're leaving an
>> entry route for Mother Nature to bite you.
>> >Phil KB9CRY
>> Which is fine if your shack is in an optimal location so that you can do
>> everything by the book, but what if it's on the second floor of an old
>> house? I
>> attempt a single-point ground in th e shack, but it is a long way from earth
>> ground. I am not so naive as to believe I'm going to be able to survive a
>> if the cables from my tower are connected. Is simple disconnection at the
>> entrance up to code? I don't know, but it's all I have.
>> 73, Pete N4ZR
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