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 <[email protected]> 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 <[email protected]> > To: Elecraft Reflector <[email protected]> > 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:[email protected] >> >> 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:[email protected] > > 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:[email protected] > > 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:[email protected] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
