Re: Topband: Spark gaps
Hi Guy, You got my curiosity up. So, there are 6 radials out of the 60 that I know where they end. I dragged out the VOM and a long lead (100') to check. Everything checked okay on those 6. No visible damage where the radials attach to a 3/4 hard Cu tubing square that is attached to the concrete pier. The Cu tubing is attached to each leg of the tower. In addition from each tower leg I have solid #4 Cu going to 8' ground rods that are 3' from the concrete. The wire continue away from the tower in these three directions with a ground rod each additional 16' for a total of 4 ground rods for each tower leg. One of the wires that points towards the house continues for another 40' where it T's to a box mounted on the side of my shed that houses the receive antenna stuff (3' x 3' aluminum plate, coax switch, preamp, common-mode choke). The ground wire continues to the large aluminum panel just inside my basement where I have mounted lightning protection devices for every coax and control wire plus a coax switch. From the ground attach point of the panel I have a #4 solid wire going out through the concrete to three 8' ground rods. Total ground rods - 22. My amp is mounted just above the panel and grounded directly to the panel. I have a #4 wire going to the ground in the breaker box. I have my coax, control cables and ground wire continuing to the shack which is right above the ground panel on the first floor. All outside ground rod connections are made with Cadwelds. All coax shields are connected to the bottom of the tower before they go underground. Also connected the shields where the hardlines terminates on the tower where I switch to Buryflex for the rotator loops. Run all coax and control cable inside the Rohn 45 (don't know if that does any good). And I even had a witness to the strike. It seems lightning struck a tree about 300' past my tower very shortly before the tower got hit. My neighbor looked up to see what got hit. My tower was in line with the tree. He was standing about 250' from the tower when it got hit. He ran inside after that. Two close strikes was enough for him. Maybe someday I will pay a price for not disconnecting anything. But after doing it this way for 33 years I have suffered virtually no damage. 73, N2TK, Tony -Original Message- From: topband-boun...@contesting.com [mailto:topband-boun...@contesting.com] On Behalf Of Guy Olinger K2AV Sent: Saturday, July 28, 2012 1:06 AM To: N2TK, Tony Cc: topband; donov...@starpower.net Subject: Re: Topband: Spark gaps What is the condition of your 160m radials after the lightning strike? 73, Guy. On Fri, Jul 27, 2012 at 7:48 PM, N2TK, Tony tony@verizon.net wrote: As a side note, last night when the storm came barreling in with very strong winds I was watching the tower as the elements whipped around. Bang! First time I saw a direct hit on the tower. Had spots in my eyes for a while. Tower is about 150' from the kitchen window. I had everything tuned off but I never disconnect anything. Was anxious when I turned on things this morning. Everything is fine except the fuse blew on the Prosistel when I turned it on. Replaced the fuse and everything is now fine. I guess my ground system is working. Couldn't find any burn marks anywhere inside or at the tower. With no visual or electrical damage maybe the tower has been hit before? By the way the tower is grounded and I shunt feed it for 160M. 73, N2TK, Tony -Original Message- From: topband-boun...@contesting.com [mailto: topband-boun...@contesting.com] On Behalf Of donov...@starpower.net Sent: Friday, July 27, 2012 10:58 AM To: topband Subject: Re: Topband: Spark gaps An air gap using one to two inch diameter balls with only a one or two millimeter gap provides a nearly uniform field resulting in the fastest breakdown at repeatable and fairly breakdown voltages but capable of withstanding kilowatt transmitter power levels. Ordinary carbon steel balls used in architectural applications should provide adequate protection if they are inspected -- and replaced if necessary -- after a lightning strike. For example, Wagner Industrial sells two inch diameter threaded steel balls for $11.00 each. There may be alternative sources. http://www.shopwagnerb2c.com/SPHERES/SPHERES_ST?categoryId=315e03cf-4f 11-4ed 9-8e89-9fea015509e5filters=sortby=1page=1pageSize=10criteria= Very hard steel balls such as carbon or tungsten are ideal for withstanding multiple lightning strikes without need for inspection and replacement, but at higher cost. The balls should be aligned in the horizontal plane, to ensure rain, do not bridge the gap. Preferably, the balls should be installed in a weather/insect/rhodent proof enclosure. 73 Frank W3LPL Original message Date: Fri, 27 Jul 2012 10:09:16 -0400 From: Tom W8JI w...@w8ji.com Subject: Topband: Spark gaps To: topband topband@contesting.com Has anyone
Re: Topband: Spark Gaps..
Bob, that an excellent idea! Dave WX7G On Jul 28, 2012 6:06 PM, Robert Briggs vk...@bigpond.com wrote: Has anyone thought about using two trailer towing balls set up for a spark gap? I use this on a 90 foot insulated mast in a very lightning prone environmentTo date (25) years, with many direct hits, I have sustained no damage...Mast is located 20 feet from my lounge room.. 73..Bob..VK3ZL.. ___ UR RST IS ... ... ..9 QSB QSB - hw? BK ___ UR RST IS ... ... ..9 QSB QSB - hw? BK
Re: Topband: Spark Gaps..
Trailer hitch balls should work fine as a lightning arrestor. Typically a trailer hitch ball has spherical sides and a flat top. The two balls should be oriented so they the spherical surfaces are side-by-side and so that rain water and debris cannot bridge them. Ideally they should be shielded from rain and insects. The gap should be adjustable, and it should be set to about the thickness of a credit card (1 to 2 mm). 73 Frank W3LPL Original message Date: Sun, 29 Jul 2012 11:33:07 -0600 From: DAVID CUTHBERT telegraph...@gmail.com Subject: Re: Topband: Spark Gaps.. To: Robert Briggs vk...@bigpond.com Cc: topband@contesting.com Bob, that an excellent idea! Dave WX7G On Jul 28, 2012 6:06 PM, Robert Briggs vk...@bigpond.com wrote: Has anyone thought about using two trailer towing balls set up for a spark gap? I use this on a 90 foot insulated mast in a very lightning prone environmentTo date (25) years, with many direct hits, I have sustained no damage...Mast is located 20 feet from my lounge room.. 73..Bob..VK3ZL.. ___ UR RST IS ... ... ..9 QSB QSB - hw? BK ___ UR RST IS ... ... ..9 QSB QSB - hw? BK ___ UR RST IS ... ... ..9 QSB QSB - hw? BK
Re: Topband: Spark Gaps..
Figuring that .045 is a standard 2000V air gap for variable caps in medium humidity it would be a good place to start. For 1500V set at .030. Everybody should have a set of feeler gauges(-; A sacrificial size 100 uH choke should suffice as a static drain and be a visible indicator of whats happening. Carl KM1H - Original Message - From: donov...@starpower.net To: 160 reflector topband@contesting.com Sent: Sunday, July 29, 2012 4:18 PM Subject: Re: Topband: Spark Gaps.. Trailer hitch balls should work fine as a lightning arrestor. Typically a trailer hitch ball has spherical sides and a flat top. The two balls should be oriented so they the spherical surfaces are side-by-side and so that rain water and debris cannot bridge them. Ideally they should be shielded from rain and insects. The gap should be adjustable, and it should be set to about the thickness of a credit card (1 to 2 mm). 73 Frank W3LPL Original message Date: Sun, 29 Jul 2012 11:33:07 -0600 From: DAVID CUTHBERT telegraph...@gmail.com Subject: Re: Topband: Spark Gaps.. To: Robert Briggs vk...@bigpond.com Cc: topband@contesting.com Bob, that an excellent idea! Dave WX7G On Jul 28, 2012 6:06 PM, Robert Briggs vk...@bigpond.com wrote: Has anyone thought about using two trailer towing balls set up for a spark gap? I use this on a 90 foot insulated mast in a very lightning prone environmentTo date (25) years, with many direct hits, I have sustained no damage...Mast is located 20 feet from my lounge room.. 73..Bob..VK3ZL.. ___ 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: 2437/5162 - Release Date: 07/29/12 ___ UR RST IS ... ... ..9 QSB QSB - hw? BK
Re: Topband: Spark gaps
I took a lightning strike to my shunt fed tower crank up earlier this year. It vaporized the #8 wire that ran from the top to the bottom of the tower. Some of the radials turned into fuses. Interestingly, not at the base of the tower, but 50 - 60 ft from the base. I disconnect all of the feed lines and control cables outside of the shack when not in use. 73 Gregg -Original Message- From: topband-boun...@contesting.com [mailto:topband-boun...@contesting.com] On Behalf Of Guy Olinger K2AV Sent: Saturday, July 28, 2012 01:06 To: N2TK, Tony Cc: topband; donov...@starpower.net Subject: Re: Topband: Spark gaps What is the condition of your 160m radials after the lightning strike? 73, Guy. On Fri, Jul 27, 2012 at 7:48 PM, N2TK, Tony tony@verizon.net wrote: As a side note, last night when the storm came barreling in with very strong winds I was watching the tower as the elements whipped around. Bang! First time I saw a direct hit on the tower. Had spots in my eyes for a while. Tower is about 150' from the kitchen window. I had everything tuned off but I never disconnect anything. Was anxious when I turned on things this morning. Everything is fine except the fuse blew on the Prosistel when I turned it on. Replaced the fuse and everything is now fine. I guess my ground system is working. Couldn't find any burn marks anywhere inside or at the tower. With no visual or electrical damage maybe the tower has been hit before? By the way the tower is grounded and I shunt feed it for 160M. 73, N2TK, Tony -Original Message- From: topband-boun...@contesting.com [mailto: topband-boun...@contesting.com] On Behalf Of donov...@starpower.net Sent: Friday, July 27, 2012 10:58 AM To: topband Subject: Re: Topband: Spark gaps An air gap using one to two inch diameter balls with only a one or two millimeter gap provides a nearly uniform field resulting in the fastest breakdown at repeatable and fairly breakdown voltages but capable of withstanding kilowatt transmitter power levels. Ordinary carbon steel balls used in architectural applications should provide adequate protection if they are inspected -- and replaced if necessary -- after a lightning strike. For example, Wagner Industrial sells two inch diameter threaded steel balls for $11.00 each. There may be alternative sources. http://www.shopwagnerb2c.com/SPHERES/SPHERES_ST?categoryId=315e03cf-4f11-4ed 9-8e89-9fea015509e5filters=sortby=1page=1pageSize=10criteria= Very hard steel balls such as carbon or tungsten are ideal for withstanding multiple lightning strikes without need for inspection and replacement, but at higher cost. The balls should be aligned in the horizontal plane, to ensure rain, do not bridge the gap. Preferably, the balls should be installed in a weather/insect/rhodent proof enclosure. 73 Frank W3LPL Original message Date: Fri, 27 Jul 2012 10:09:16 -0400 From: Tom W8JI w...@w8ji.com Subject: Topband: Spark gaps To: topband topband@contesting.com Has anyone looked at, or looked for, cheap electric fence gaps?? My system copper pipes near tower legs work great for me on rigid towers, I can bend them so they spring away from the tower and then slide an inner pipe in or out to set gap distance. I'm thinking of gaps for wire antennas. Maybe something is good from some other application that is a good bit better than a spark plug. ___ UR RST IS ... ... ..9 QSB QSB - hw? BK ___ UR RST IS ... ... ..9 QSB QSB - hw? BK ___ UR RST IS ... ... ..9 QSB QSB - hw? BK ___ UR RST IS ... ... ..9 QSB QSB - hw? BK ___ UR RST IS ... ... ..9 QSB QSB - hw? BK
Re: Topband: Spark gaps
Sorry...couldn't resist http://www.youtube.com/watch?v=g23GiivXC78 On 7/27/2012 4:31 PM, kd9sv wrote: Silly me, and to think they were probably referring to Carbon Steel Balls not Carbon balls...de gary -Original Message- From: topband-boun...@contesting.com [mailto:topband-boun...@contesting.com] On Behalf Of donov...@starpower.net Sent: Friday, July 27, 2012 5:26 PM To: topband Subject: Re: Topband: Spark gaps This link shows the base of a typical AM broadcast tower, with two hard steel balls used as lightning protection. At kilowatt power levels its not unusual to use a credit card to set the gap. http://www.thebdr.net/articles/steel/twrs/LimitingStatic.pdf 73 Frank W3LPL Original message Date: Fri, 27 Jul 2012 16:29:15 -0400 From: Tom W8JI w...@w8ji.com Subject: Re: Topband: Spark gaps To: Mike Waters mikew...@gmail.com, topband topband@contesting.com Man, I don't know, Dave. How long have they been selling those carbon balls for that purpose? I've never seen a carbon ball in a lightning gap application. I'd have to see a few after being in action a long time before trusting them. Broadcast stations use hard metallic balls, as do electrical substations and other applications where the peak voltage is near gap voltage. Polished round gaps have more consistent breakdown. If there is a great deal of headroom between operating and breakover threshold, a pointed gap works OK. ___ UR RST IS ... ... ..9 QSB QSB - hw? BK ___ UR RST IS ... ... ..9 QSB QSB - hw? BK ___ UR RST IS ... ... ..9 QSB QSB - hw? BK -- 73, Gary K9GS Greater Milwaukee DX Association: http://www.gmdxa.org Society of Midwest Contesters: http://www.w9smc.com CW Ops #1032 http://www.cwops.org ___ UR RST IS ... ... ..9 QSB QSB - hw? BK
Re: Topband: Spark gaps
Yes a direct hit should vaporize a spark plug. For a 100 kA hit two 1 diameter rounded steel balls may survive. Note that Ross Engineering uses carbon balls on their spark gaps. At 50 kA/us every inch of wire will have a voltage drop of 500 to 1000 volts, so very short wires are in order. Wide copper straps having a length-to-width ratio of 5:1 are good. Dave WX7G On Jul 27, 2012 8:09 AM, Tom W8JI w...@w8ji.com wrote: Has anyone looked at, or looked for, cheap electric fence gaps?? My system copper pipes near tower legs work great for me on rigid towers, I can bend them so they spring away from the tower and then slide an inner pipe in or out to set gap distance. I'm thinking of gaps for wire antennas. Maybe something is good from some other application that is a good bit better than a spark plug. ___ UR RST IS ... ... ..9 QSB QSB - hw? BK ___ UR RST IS ... ... ..9 QSB QSB - hw? BK
Re: Topband: Spark gaps
An air gap using one to two inch diameter balls with only a one or two millimeter gap provides a nearly uniform field resulting in the fastest breakdown at repeatable and fairly breakdown voltages but capable of withstanding kilowatt transmitter power levels. Ordinary carbon steel balls used in architectural applications should provide adequate protection if they are inspected -- and replaced if necessary -- after a lightning strike. For example, Wagner Industrial sells two inch diameter threaded steel balls for $11.00 each. There may be alternative sources. http://www.shopwagnerb2c.com/SPHERES/SPHERES_ST?categoryId=315e03cf-4f11-4ed9-8e89-9fea015509e5filters=sortby=1page=1pageSize=10criteria= Very hard steel balls such as carbon or tungsten are ideal for withstanding multiple lightning strikes without need for inspection and replacement, but at higher cost. The balls should be aligned in the horizontal plane, to ensure rain, do not bridge the gap. Preferably, the balls should be installed in a weather/insect/rhodent proof enclosure. 73 Frank W3LPL Original message Date: Fri, 27 Jul 2012 10:09:16 -0400 From: Tom W8JI w...@w8ji.com Subject: Topband: Spark gaps To: topband topband@contesting.com Has anyone looked at, or looked for, cheap electric fence gaps?? My system copper pipes near tower legs work great for me on rigid towers, I can bend them so they spring away from the tower and then slide an inner pipe in or out to set gap distance. I'm thinking of gaps for wire antennas. Maybe something is good from some other application that is a good bit better than a spark plug. ___ UR RST IS ... ... ..9 QSB QSB - hw? BK ___ UR RST IS ... ... ..9 QSB QSB - hw? BK
Re: Topband: Spark gaps
You can get chrome steel balls too and they are *very* hard (usually used for ball bearings). You have to drill them with solid carbide drills. I don't think it would be possible to thread the holes using normal taps though. -Bill [snip] Very hard steel balls such as carbon or tungsten are ideal for withstanding multiple lightning strikes without need for inspection and replacement, but at higher cost. ___ UR RST IS ... ... ..9 QSB QSB - hw? BK
Re: Topband: Spark gaps
I don't think carbon balls are suitable for lightning protection. Think of the voltage drop that would appear across each ball during a direct hit. I think they would vaporize. At http://www.rossengineeringcorp.com/hv_spark_gap.htm lightning is not one of the applications mentioned for their carbon balls. 73, Mike www.w0btu.com On Fri, Jul 27, 2012 at 9:35 AM, DAVID CUTHBERT telegraph...@gmail.comwrote: Note that Ross Engineering uses carbon balls on their spark gaps. ___ UR RST IS ... ... ..9 QSB QSB - hw? BK
Re: Topband: Spark gaps
Google carbon ball gap lightning. Dave On Jul 27, 2012 9:33 AM, Mike Waters mikew...@gmail.com wrote: I don't think carbon balls are suitable for lightning protection. Think of the voltage drop that would appear across each ball during a direct hit. I think they would vaporize. At http://www.rossengineeringcorp.com/hv_spark_gap.htm lightning is not one of the applications mentioned for their carbon balls. 73, Mike www.w0btu.com On Fri, Jul 27, 2012 at 9:35 AM, DAVID CUTHBERT telegraph...@gmail.com wrote: Note that Ross Engineering uses carbon balls on their spark gaps. ___ UR RST IS ... ... ..9 QSB QSB - hw? BK ___ UR RST IS ... ... ..9 QSB QSB - hw? BK
Re: Topband: Spark gaps
www.rossengineeringcorp.com/toroids_spheres_coronary_nuts.htm Ross recommends carbon for lightning. Dave WX7G On Jul 27, 2012 9:33 AM, Mike Waters mikew...@gmail.com wrote: I don't think carbon balls are suitable for lightning protection. Think of the voltage drop that would appear across each ball during a direct hit. I think they would vaporize. At http://www.rossengineeringcorp.com/hv_spark_gap.htm lightning is not one of the applications mentioned for their carbon balls. 73, Mike www.w0btu.com On Fri, Jul 27, 2012 at 9:35 AM, DAVID CUTHBERT telegraph...@gmail.com wrote: Note that Ross Engineering uses carbon balls on their spark gaps. ___ UR RST IS ... ... ..9 QSB QSB - hw? BK ___ UR RST IS ... ... ..9 QSB QSB - hw? BK
Re: Topband: Spark gaps
- Original Message - From: Mike Waters mikew...@gmail.com To: topband topband@contesting.com Sent: Friday, July 27, 2012 11:33 AM Subject: Re: Topband: Spark gaps I don't think carbon balls are suitable for lightning protection. I agree. The last thing we want is high surface resistivity, unless we want something to heat and vaporize. With high core resistivity, we could make it explode. :-) ___ UR RST IS ... ... ..9 QSB QSB - hw? BK
Re: Topband: Spark gaps
www.rossengineeringcorp.com/toroids_spheres_corona_nuts.htm On Jul 27, 2012 9:43 AM, DAVID CUTHBERT telegraph...@gmail.com wrote: www.rossengineeringcorp.com/toroids_spheres_coronary_nuts.htm Ross recommends carbon for lightning. Dave WX7G On Jul 27, 2012 9:33 AM, Mike Waters mikew...@gmail.com wrote: I don't think carbon balls are suitable for lightning protection. Think of the voltage drop that would appear across each ball during a direct hit. I think they would vaporize. At http://www.rossengineeringcorp.com/hv_spark_gap.htm lightning is not one of the applications mentioned for their carbon balls. 73, Mike www.w0btu.com On Fri, Jul 27, 2012 at 9:35 AM, DAVID CUTHBERT telegraph...@gmail.com wrote: Note that Ross Engineering uses carbon balls on their spark gaps. ___ UR RST IS ... ... ..9 QSB QSB - hw? BK ___ UR RST IS ... ... ..9 QSB QSB - hw? BK
Re: Topband: Spark gaps
Man, I don't know, Dave. How long have they been selling those carbon balls for that purpose? I don't have the figures in front of me, but carbon has a significant amount of resistance. (Maybe that's the secret: the current gets limited as a result. :-) It would be interesting to calculate the resistance of a carbon sphere sometime (how big are those?). Then we could roughly estimate the voltage drop across it and so come up with a ballpark figure of the instantaneous power dissipated in those balls. At that point, someone with way too much time on their hands could estimate the temperature rise based on the specific heat of carbon. :-) 73, Mike www.w0btu.com On Fri, Jul 27, 2012 at 2:42 PM, DAVID CUTHBERT telegraph...@gmail.comwrote: www.rossengineeringcorp.com/toroids_spheres_corona_nuts.htm On Jul 27, 2012 9:43 AM, DAVID CUTHBERT telegraph...@gmail.com wrote: http://www.rossengineeringcorp.com/toroids_spheres_coronary_nuts.htm Ross recommends carbon for lightning. On Jul 27, 2012 9:33 AM, Mike Waters mikew...@gmail.com wrote: I don't think carbon balls are suitable for lightning protection. Think of the voltage drop that would appear across each ball during a direct hit. I think they would vaporize. ___ UR RST IS ... ... ..9 QSB QSB - hw? BK
Re: Topband: Spark gaps
Man, I don't know, Dave. How long have they been selling those carbon balls for that purpose? I've never seen a carbon ball in a lightning gap application. I'd have to see a few after being in action a long time before trusting them. Broadcast stations use hard metallic balls, as do electrical substations and other applications where the peak voltage is near gap voltage. Polished round gaps have more consistent breakdown. If there is a great deal of headroom between operating and breakover threshold, a pointed gap works OK. ___ UR RST IS ... ... ..9 QSB QSB - hw? BK
Re: Topband: Spark gaps
Mike, here it is. The resistivity of amorphous carbon is 35 u ohm meters (That's a 1 meter cube) A 1 cube has a resistivity of 1.4 m ohms, a one inch sphere about 3 m ohms. 100 kA for 20 us dumps 600 J into it. The density of carbon is 2.3 g/cm cubed The 1 inch sphere has a mass of 20 grams The specific heat capacity of carbon is 700 J/kg k The observe heats 43 deg C Dave WX7G On Jul 27, 2012 2:18 PM, Mike Waters mikew...@gmail.com wrote: Man, I don't know, Dave. How long have they been selling those carbon balls for that purpose? I don't have the figures in front of me, but carbon has a significant amount of resistance. (Maybe that's the secret: the current gets limited as a result. :-) It would be interesting to calculate the resistance of a carbon sphere sometime (how big are those?). Then we could roughly estimate the voltage drop across it and so come up with a ballpark figure of the instantaneous power dissipated in those balls. At that point, someone with way too much time on their hands could estimate the temperature rise based on the specific heat of carbon. :-) 73, Mike www.w0btu.com On Fri, Jul 27, 2012 at 2:42 PM, DAVID CUTHBERT telegraph...@gmail.com wrote: www.rossengineeringcorp.com/toroids_spheres_corona_nuts.htm On Jul 27, 2012 9:43 AM, DAVID CUTHBERT telegraph...@gmail.com wrote: http://www.rossengineeringcorp.com/toroids_spheres_coronary_nuts.htm Ross recommends carbon for lightning. On Jul 27, 2012 9:33 AM, Mike Waters mikew...@gmail.com wrote: I don't think carbon balls are suitable for lightning protection. Think of the voltage drop that would appear across each ball during a direct hit. I think they would vaporize. ___ UR RST IS ... ... ..9 QSB QSB - hw? BK ___ UR RST IS ... ... ..9 QSB QSB - hw? BK
Re: Topband: Spark gaps
I do make (all too frequent) mistakes so check away. Carbon is 2000 times more resistive than copper. Being more resistive the carbon skin depth at lightning frequencies is much deeper than copper or steel (note the steel is magnetically saturated). Dave On Jul 27, 2012 3:26 PM, Mike Waters mikew...@gmail.com wrote: Thanks, Dave. That's amazing, and I won't argue anymore, even though I didn't (and probably won't) check your figures. I would have thought that the carbon sphere would have a MUCH greater resistance than .003 ohms. 73, Mike www.w0btu.com On Fri, Jul 27, 2012 at 3:42 PM, DAVID CUTHBERT telegraph...@gmail.comwrote: A ... one inch sphere about 3 m ohms. ... The observe heats 43 deg C ___ UR RST IS ... ... ..9 QSB QSB - hw? BK
Re: Topband: Spark gaps
As a side note, last night when the storm came barreling in with very strong winds I was watching the tower as the elements whipped around. Bang! First time I saw a direct hit on the tower. Had spots in my eyes for a while. Tower is about 150' from the kitchen window. I had everything tuned off but I never disconnect anything. Was anxious when I turned on things this morning. Everything is fine except the fuse blew on the Prosistel when I turned it on. Replaced the fuse and everything is now fine. I guess my ground system is working. Couldn't find any burn marks anywhere inside or at the tower. With no visual or electrical damage maybe the tower has been hit before? By the way the tower is grounded and I shunt feed it for 160M. 73, N2TK, Tony -Original Message- From: topband-boun...@contesting.com [mailto:topband-boun...@contesting.com] On Behalf Of donov...@starpower.net Sent: Friday, July 27, 2012 10:58 AM To: topband Subject: Re: Topband: Spark gaps An air gap using one to two inch diameter balls with only a one or two millimeter gap provides a nearly uniform field resulting in the fastest breakdown at repeatable and fairly breakdown voltages but capable of withstanding kilowatt transmitter power levels. Ordinary carbon steel balls used in architectural applications should provide adequate protection if they are inspected -- and replaced if necessary -- after a lightning strike. For example, Wagner Industrial sells two inch diameter threaded steel balls for $11.00 each. There may be alternative sources. http://www.shopwagnerb2c.com/SPHERES/SPHERES_ST?categoryId=315e03cf-4f11-4ed 9-8e89-9fea015509e5filters=sortby=1page=1pageSize=10criteria= Very hard steel balls such as carbon or tungsten are ideal for withstanding multiple lightning strikes without need for inspection and replacement, but at higher cost. The balls should be aligned in the horizontal plane, to ensure rain, do not bridge the gap. Preferably, the balls should be installed in a weather/insect/rhodent proof enclosure. 73 Frank W3LPL Original message Date: Fri, 27 Jul 2012 10:09:16 -0400 From: Tom W8JI w...@w8ji.com Subject: Topband: Spark gaps To: topband topband@contesting.com Has anyone looked at, or looked for, cheap electric fence gaps?? My system copper pipes near tower legs work great for me on rigid towers, I can bend them so they spring away from the tower and then slide an inner pipe in or out to set gap distance. I'm thinking of gaps for wire antennas. Maybe something is good from some other application that is a good bit better than a spark plug. ___ UR RST IS ... ... ..9 QSB QSB - hw? BK ___ UR RST IS ... ... ..9 QSB QSB - hw? BK ___ UR RST IS ... ... ..9 QSB QSB - hw? BK
Re: Topband: Spark gaps
What is the condition of your 160m radials after the lightning strike? 73, Guy. On Fri, Jul 27, 2012 at 7:48 PM, N2TK, Tony tony@verizon.net wrote: As a side note, last night when the storm came barreling in with very strong winds I was watching the tower as the elements whipped around. Bang! First time I saw a direct hit on the tower. Had spots in my eyes for a while. Tower is about 150' from the kitchen window. I had everything tuned off but I never disconnect anything. Was anxious when I turned on things this morning. Everything is fine except the fuse blew on the Prosistel when I turned it on. Replaced the fuse and everything is now fine. I guess my ground system is working. Couldn't find any burn marks anywhere inside or at the tower. With no visual or electrical damage maybe the tower has been hit before? By the way the tower is grounded and I shunt feed it for 160M. 73, N2TK, Tony -Original Message- From: topband-boun...@contesting.com [mailto: topband-boun...@contesting.com] On Behalf Of donov...@starpower.net Sent: Friday, July 27, 2012 10:58 AM To: topband Subject: Re: Topband: Spark gaps An air gap using one to two inch diameter balls with only a one or two millimeter gap provides a nearly uniform field resulting in the fastest breakdown at repeatable and fairly breakdown voltages but capable of withstanding kilowatt transmitter power levels. Ordinary carbon steel balls used in architectural applications should provide adequate protection if they are inspected -- and replaced if necessary -- after a lightning strike. For example, Wagner Industrial sells two inch diameter threaded steel balls for $11.00 each. There may be alternative sources. http://www.shopwagnerb2c.com/SPHERES/SPHERES_ST?categoryId=315e03cf-4f11-4ed 9-8e89-9fea015509e5filters=sortby=1page=1pageSize=10criteria= Very hard steel balls such as carbon or tungsten are ideal for withstanding multiple lightning strikes without need for inspection and replacement, but at higher cost. The balls should be aligned in the horizontal plane, to ensure rain, do not bridge the gap. Preferably, the balls should be installed in a weather/insect/rhodent proof enclosure. 73 Frank W3LPL Original message Date: Fri, 27 Jul 2012 10:09:16 -0400 From: Tom W8JI w...@w8ji.com Subject: Topband: Spark gaps To: topband topband@contesting.com Has anyone looked at, or looked for, cheap electric fence gaps?? My system copper pipes near tower legs work great for me on rigid towers, I can bend them so they spring away from the tower and then slide an inner pipe in or out to set gap distance. I'm thinking of gaps for wire antennas. Maybe something is good from some other application that is a good bit better than a spark plug. ___ UR RST IS ... ... ..9 QSB QSB - hw? BK ___ UR RST IS ... ... ..9 QSB QSB - hw? BK ___ UR RST IS ... ... ..9 QSB QSB - hw? BK ___ UR RST IS ... ... ..9 QSB QSB - hw? BK
Re: Topband: Spark gaps
Take 2 rods and grind a point on each rod. Point the points toward each other. There is your spark gap. You can do the dame thing with copper flat stock used on building grounds in electrical valts. Stay on course, fight a good fight, and keep the faith. Jim K9TF/WA9YSD ___ UR RST IS ... ... ..9 QSB QSB - hw? BK
