[Elecraft] Lightning season is on the way in New Mexico.
Phil Hystad
phystad at mac.com
Mon Mar 28 22:53:15 EDT 2011
You guys should all move to the northwest, such as Seattle. Lightning is more rare then a 100 degree summer day. It happens but definitely not often.
Sent from my iPad
On Mar 28, 2011, at 5:49 PM, Mel Farrer <farrerfolks at yahoo.com> wrote:
> All of this is of course, very good advice. I would like to add a little humor
> experience driving through the southwest on the way back to my post at Fort
> Gordon, GA.
>
>
> I left CA and went to the southern route to GA which took me to Flagstaff, AZ
> and east. While on the way, I had my 6 meter antenna on the back of my 1957
> Chev convertible and the rig unconnected in the back seat. While driving
> across the desert, in the afternoon while the overhead storm was obvious, I
> heard some snapping sounds, but could not find a source. I stopped for dinner
> and got back in the car to continue...... After a while I heard the snapping
> sound again. But everything still seemed fine. When the light faded and the
> sky darken, the snapping sound was accompanied by a flash in the car. I pulled
> off and looked around when it flashed again, it was the end of the coax
> connector and the static electricity was arcing across the end of the
> connector. I piece of gum wrapper across the end stopped the arcing and I
> continued to Ft. Gordon at ease.
>
>
> Mel, K6KBE
>
>
>
>
>
> ________________________________
> From: FredJensen <k6dgw at foothill.net>
> To: Elecraft Reflector <elecraft at mailman.qth.net>
> Sent: Mon, March 28, 2011 4:39:36 PM
> Subject: Re: [Elecraft] Lightning season is on the way in New Mexico.
>
> Grounding and lightning protection is not a simple subject Phil. Here's
> what I would recommend:
>
> If your home is wired to NEC standards, the neutral [center-tap on the
> pole pig] will be tied to the safety ground [green wire in your outlets]
> and earth at the service entrance ... only. This means that the "green
> wire" in each outlet snakes back to the service entrance before
> encountering a "real" ground. It thus makes a useless RF ground and
> lightning is RF [see below].
>
> A. You *must* tie your ground rod back to the ground at the entrance
> panel. NEC requires it and if it isn't so tied, it can create a real
> safety hazard if you should encounter a ground fault. Make it as short
> as possible, buried is best, but if short means run under the house,
> that's OK. Use #14 copper or larger.
>
> B. AC is excluded from the inside of a conductor by the magnetic field
> it creates, and flows near the surface [skin] effect]. The higher the
> frequency, the closer to the surface it is. The conductors on one of
> the original 230 KV lines from Hoover Dam to Los Angeles are hollow for
> that reason.
>
> C. Lightning currents are mainly RF, and flow only on the very surface
> of the conductor and you want a lot of surface area, volume contributes
> almost nothing. So, wide copper strap is good. Large gauge stranded
> copper wire is less effective but better than solid wire. For the fire
> lookouts on peaks here in the Sierra Nevada, they use 3/8" - 1/2"
> stranded wire running around the roof, catwalks, and tower legs, bonded
> to everything including an extensive ground system.
>
> D. Surviving a direct hit to your tower or antenna is problematical at
> best. Even if you disconnect and ground your antenna [and rotator]
> cables, the induced currents will create high peak potentials to your
> equipment [and everything else in the house]. You can't stop that from
> happening, and your radio chassis can momentarily rise to very high
> potentials.The grounding goal for your equipment is to "keep it all
> together." The radio chassis can experience a peak pulse, but if
> everything else also gets that same pulse, the differential potential
> between them is very low, and little current will flow. The way you do
> this is to bring your ground strap into the shack, and using the
> shortest wiring you can, ground *each* piece of equipment *separately*
> to the same point on the strap.
>
> E. A grounded entrance panel for your coax and rotator cables is very
> good, use Polyphasers or similar to bring the cables through. They
> won't survive a direct hit, but in that case, that's the least of your
> worries, your house may be on fire by then. :-( They will clamp off
> induced pulses however and limit potential excursions on your equipment.
>
> F. Unless your home is on stilts over salt water [unlikely in NM :-) ]
> I'd guess that your ground rod is probably pretty high impedance for any
> currents generated by lightning. At the TV station I worked at in
> college [500' tower on a 1,300' ridge], the ground system ran all
> around the building with a bunch of ground rods, and included things
> like the tower, the fridge, plumbing, the 3 1/8" hard-line exterior,
> even the gate on the road, and the steel trench covers inside, They
> still made a deafening "clang" when we took a nearby strike. Hams do
> install systems like that around their houses, it's expensive and it's
> really a trade off with risk.
>
> G. If you have an Elecraft rig, you're covered. If you don't, make
> sure there's a bleed [RF choke or high value resistor] across the
> antenna connector. Precip static can sound innocuous if annoying, but
> without the bleed, it can store charge in the input circuit and
> ultimately cream it. We killed 2 IC-756PRO II's in 2009 from this in a
> snowstorm during the Cal QSO Party in Alpine County.
>
> If you have any specific questions, I'd recommend first contacting Jim,
> K9YC [who is really near Santa Cruz CA]. He has a wealth of information
> and tutorials on his web site. The grandson of Art, my Elmer of 57
> years ago, W6RMK, now holds his grandad's call and has made his living
> as a lightning expert. If some question comes up, I'll be glad to take
> it to him. This pretty much exhausts my knowledge.
>
> 73,
>
> Fred K6DGW
> Auburn CA
> On 3/28/2011 9:35 PM, Phil Townsend wrote:
>> Lightning question:
>>
>> I have driven an 8 foot copper clad rod just out side my operating station. Its
>> about 6 feet from the rod to my desk.
>> I have attached a solid copper wire (1/4" thick) to the ground post (with a
>> ground rod clamp) The wire goes thru the wall and is bonded to a copper pipe
>> that is 1-1/8" wide that is just under the desk.
>>
>> So on to my question:
>> What is the BEST way to connect my equipment (k3, SB-200 and a remote coax
>> switch) to the copper pipe?
>>
>> Coax braid from RG8 or solid copper wire? and why....
>>
>>
>> Thank You guys...
>>
>> Phil
>> Santa Fe
>>
>> soon to be a xx5SSR...
>> ______________________________________________________________
>> Elecraft mailing list
>> Home: http://mailman.qth.net/mailman/listinfo/elecraft
>> Help: http://mailman.qth.net/mmfaq.htm
>> Post: mailto:Elecraft at mailman.qth.net
>>
>> This list hosted by: http://www.qsl.net
>> Please help support this email list: http://www.qsl.net/donate.html
>>
>>
>>
>>
>> -----
>> No virus found in this message.
>> Checked by AVG - www.avg.com
>> Version: 10.0.1204 / Virus Database: 1498/3535 - Release Date: 03/28/11
>>
>>
>
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:Elecraft at mailman.qth.net
>
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html
>
>
>
>
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:Elecraft at mailman.qth.net
>
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html
More information about the Elecraft
mailing list