If you use an automotive spark plug make sure its not the resistor type. Carl KM1H
----- Original Message ----- From: "DAVID CUTHBERT" <telegraph...@gmail.com> To: "Bob Kupps" <n...@yahoo.com> Cc: "topband" <topband@contesting.com> Sent: Friday, July 27, 2012 8:24 AM Subject: Re: Topband: Fw: Choke Construction Info Needed >I agree with Tom and Bob that the big, heavy choke is not needed. Even it > offers too much inductance to be an effective lightning path. > > A spark gap is the thing to use across the choke or shorted 90 degree > feedline. It should have a weather cover and be set close but not too > close. See ROSS ENGINEERING for a picture of a spark gap. I've use 1/4" > carriage bolts for spark gaps at 1 kA. I would use a larger one for > protection against a direct lightning strike. Only 1% of strikes reach 100 > kA but I think that's a good current to design to. > > http://www.rossengineeringcorp.com/hv_spark_gap.htm > > Dave WX7G > > > > On Thu, Jul 26, 2012 at 7:53 PM, Bob Kupps <n...@yahoo.com> wrote: > >> Hi Phil >> >> I'm no expert but plan to use a quarter wave shorted stub of RG6 at the >> feed point of my verticals for static drain and harmonic reduction, along >> with a spark gap in the event of a close strike. >> >> 73 Bob >> >> ----- Forwarded Message ----- >> From: Phil Clements <philcleme...@centurylink.net> >> To: topband@contesting.com >> Sent: Friday, July 27, 2012 2:03 AM >> Subject: Topband: Choke Construction Info Needed >> >> I need to construct a heavy-duty choke to be installed from the feed >> point >> of my 160 meter vertical to ground, for static drain and for lightning >> protection. How large does the wire, form, and inductance need to be? >> >> >> >> Thanks in advance for your expertize! >> >> >> >> (((73))) >> >> Phil, K5PC >> >> >> >> _______________________________________________ >> UR RST IS ... ... ..9 QSB QSB - hw? BK >> _______________________________________________ >> UR RST IS ... ... ..9 QSB QSB - hw? BK >> > _______________________________________________ > UR RST IS ... ... ..9 QSB QSB - hw? BK > > > ----- > No virus found in this message. > Checked by AVG - www.avg.com > Version: 10.0.1424 / Virus Database: 2437/5158 - Release Date: 07/27/12 > _______________________________________________ UR RST IS ... ... ..9 QSB QSB - hw? BK