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Thunderbolt and lightning, very, very frightening me
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Full disclosure, I know better.? As we enter thunderstorm season around here lightning surge moves further up my list of issues to address.? I have one RG8X cable coming in through a window that I connect to whatever radio I am playing with at the time (BITX40, ?BITX or SDR).? I am guilty of using a temporary solution long enough to bring the temporary status into question.? My current laughable protection scheme is lacking.? If I am away for a while or the sky looks questionable I disconnect the cable and leave it sitting loose.? If it looks really bad I have weatherproofed the cable connector and thrown it back out the window.? On my list is to at least properly ground the cable where it enters the structure instead of pretending to operate portable in my house.? So now that I have embarrassingly admitted my sins to the group my question is this, what are you doing?
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After getting struck by lightning once, I have my ladder line grounded through its balun to a ground bar in my shack right where it enters. This will not protect from a direct strike, but it will handle nearby discharges. A direct strike will vaporize my ladder line, so there is no point in me going over the top protecting it.
At the shack subpanel, I put in an 8ft galvinzed rod connected to the panel with 8ga wire. Then from the panel it goes to a ground bar up on the wall, where all my equipment is grounded to. The tower outside has three of these 8ft galvanized rods on it, one off of each point, all bonded together with 8ga wire. The tower's ground is seperate from the building's due to the fact I would have to cross three cables from the cable co at six inche depth.? I am not the best to ask on this subject, but this is just what I have setup. -- ---------- N5WLF, Greggory (or my nickname, Ghericoan) General Class, Digital Radio Hobbyist |
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Doug,? A ground rod outside (preferable a 8ft or longer...) with a Polyphaser arrester at the top of it
and the cable connecting to that first.? Then a COAX coming inside.? That is a generally safer and brings all static charges to ground first.?? To make it NEC (national Electric code) a wire #6 or heavier from that ground rod to the house ground usually near the power entrance is required.? (all grounds bonded together.). I also advise for dipoles and other non DC shorted (and grounded) antennas a resistor at the feed point of 100K (2W) to bleed static as well.? Static build up from wind can be as damaging as a bolt from the sky just not as noisy. Disconnectig is good practice but a grounded and suppred connection outside its advised. Allison |
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Brian L. Davis
Grounding experiences, from my commercial radio days, says to not take the equipment ground to the electrical panel ground.
The problem is that if your radio antenna or equipment ground is better than the provider ground, lightning will travel from the electrical wiring feeding the house to your equipment ground. We ran into this at remote tower sites as well.? If we grounded the tower and equipment it would always get hit but if we didn't ground the tower and equipment there was no "ground" for the lightning to flow to. When we had a building with a grounded tower we never tied to the commercial ground as the tower ground was always better than the panel ground and would draw lightning from the distribution lines to the tower ground. Just a thought. |
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No question that is the correct way to do things.? I've actually had a polyphaser protector bookmarked and just got cheap and didn't want to spend almost as much as the radio is worth to protect it which I know is no excuse.
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Does anyone have any experience with Altelix? Looks like it might be a good enough solution at a much lower price point.? On Tue, May 8, 2018 at 08:24 am, ajparent1/KB1GMX wrote: Doug,? A ground rod outside (preferable a 8ft or longer...) with a Polyphaser arrester at the top of it ? -- |
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Looks like good advice.
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The Polyphaser stuff has been around for awhile, and is designed for this kind of use. If you are in an area that sees lightning, you want a proven system. And you want to follow all instructions closely. Here's a discussion on eham that might put the fear of god in you. ? ?? Unfortunately, those whose budget just barely covers a Bitx40 might decide to go without. This one is good to a kilowatt, $68.99 plus shipping.? ? ? ?? Plus multiple ground rods, #6 copper wire, ... Gets worse if you have multiple antennas. One of these gas discharge tubes might do it for cheap: ? ?? but I'm not about to hazard a guess as to what's appropriate around lightning. And that eham discussion suggests the Polyphaser thing is more than just a GDT, has some caps in it too, and I have no idea what else.? Anybody with a cheaper solution they feel is adequate for QRP levels? I'm sure lightning could find a way to bite us here. But being off grid with no landline phone has its advantages. While in college I spent summers on BLM fire crews, once spent a couple weeks in a tower spelling the regular lookout.? They take lots of lightning. Had a special stool you could cower on in the center of the floor during a storm, big honking glass insulators on the bottom of the legs. Just sit there and watch the sparks fly about within the cabin a few feet away. And then when it was over, the VHF radio still worked. Jerry On Tue, May 8, 2018 at 08:24 am, ajparent1/KB1GMX wrote:
Doug,? A ground rod outside (preferable a 8ft or longer...) with a Polyphaser arrester at the top of it |
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Gordon Gibby
开云体育I've disassembled a Polyphaser before to conform what is in it.??
It is a very simple device.? ?A $3 gas discharge tube.? (I prefer the one with ratings to 20kA) A series capacitor --- actually two in parallel probably to reduce inductance A shunt resistor to drain off static so it doesn't build up and then Pop across the gas discharge tube.? ? I think it might be brighter to put the shunt resistor across the ANTENNA side of the capacitor.? ?And you could even put another one across the Gas Discharge Tube. Most people seem to think 100K ohm maybe 1 watt or more is reasonable.
We buillt these locally.? ?The ground connection (for lightninng) of course is the important part.? Shortest straightest biggest wire to the best ground you have.??
Since your feedline and antenna constitute a low-pass filter....this turns out to have been useful against EMP (regardless of what some say) as proven by articles published by ARRL in the 1980's.???
cheers, gordon
From: [email protected] <[email protected]> on behalf of Jerry Gaffke via Groups.Io <jgaffke@...>
Sent: Tuesday, May 8, 2018 12:51 PM To: [email protected] Subject: Re: [BITX20] Thunderbolt and lightning, very, very frightening me ?
Looks like good advice.
The Polyphaser stuff has been around for awhile, and is designed for this kind of use. If you are in an area that sees lightning, you want a proven system. And you want to follow all instructions closely. Here's a discussion on eham that might put the fear of god in you. ? ?? Unfortunately, those whose budget just barely covers a Bitx40 might decide to go without. This one is good to a kilowatt, $68.99 plus shipping.? ? ? ?? Plus multiple ground rods, #6 copper wire, ... Gets worse if you have multiple antennas. One of these gas discharge tubes might do it for cheap: ? ?? but I'm not about to hazard a guess as to what's appropriate around lightning. And that eham discussion suggests the Polyphaser thing is more than just a GDT, has some caps in it too, and I have no idea what else.? Anybody with a cheaper solution they feel is adequate for QRP levels? I'm sure lightning could find a way to bite us here. But being off grid with no landline phone has its advantages. While in college I spent summers on BLM fire crews, once spent a couple weeks in a tower spelling the regular lookout.? They take lots of lightning. Had a special stool you could cower on in the center of the floor during a storm, big honking glass insulators on the bottom of the legs. Just sit there and watch the sparks fly about within the cabin a few feet away. And then when it was over, the VHF radio still worked. Jerry On Tue, May 8, 2018 at 08:24 am, ajparent1/KB1GMX wrote: Doug,? A ground rod outside (preferable a 8ft or longer...) with a Polyphaser arrester at the top of it |
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Gordon Gibby
开云体育Here's a constuction article: ? sorry for the misspelling.
I would put resistors shunting BOTH sides of the capacitor if you're going to do the capacitor.? ? You don't want the gas discharge tube popping off all the time --- it can damage transceivers and also itself with the changes that occur on its electrodes --- I got that from an engineer with a lot more experience than me.? ?If you have a choke or something
else that dc shorts your antenna then the resistors will be of less importance but they are basically non-existent compared to the 50ohm ac impedances your're working with.??
Of course, you pick the voltge considering the peak AC voltage for the peak SWR that you're likely to encounter.
For most 50 ohm systems of 100 watts or less and SWRs of 2:1 or less in general, I tend to go with 230-250 volt GDTs.? ?They are not perfect, they have tolerances also.
If you get hit by a REAL bolt....all of this is going to fry anyway but your house might not.? ?The real goal is to keep nearby strikes from taking out your radio gear.? ?I live in Gainesville Florda just outside the peak in Orlando Florida and knock on
wood I have WINLINK and SHARES gateways going 24/7/365 for 2-3 years now and so far, all is OK.? The wire antennas are always somewhat lower than the peaks of their trees.? ?My house DID get hit while being constructed (before the trees.....) and several feet
of home security wiring ceased to exist.? ?We then spent $3000+ and had enormous wires and lightning arrestors and ground rods on four sides of the house creating a virtual low frequency faraday cage with wires that are as big as my thumb.? ? No problems since.??
Hope this helps, gordon
From: [email protected] <[email protected]> on behalf of Gordon Gibby <ggibby@...>
Sent: Tuesday, May 8, 2018 3:18 PM To: [email protected] Subject: Re: [BITX20] Thunderbolt and lightning, very, very frightening me ?
I've disassembled a Polyphaser before to conform what is in it.??
It is a very simple device.? ?A $3 gas discharge tube.? (I prefer the one with ratings to 20kA) A series capacitor --- actually two in parallel probably to reduce inductance A shunt resistor to drain off static so it doesn't build up and then Pop across the gas discharge tube.? ? I think it might be brighter to put the shunt resistor across the ANTENNA side of the capacitor.? ?And you could even put another one across the Gas Discharge Tube. Most people seem to think 100K ohm maybe 1 watt or more is reasonable.
We buillt these locally.? ?The ground connection (for lightninng) of course is the important part.? Shortest straightest biggest wire to the best ground you have.??
Since your feedline and antenna constitute a low-pass filter....this turns out to have been useful against EMP (regardless of what some say) as proven by articles published by ARRL in the 1980's.???
cheers, gordon
From: [email protected] <[email protected]> on behalf of Jerry Gaffke via Groups.Io <jgaffke@...>
Sent: Tuesday, May 8, 2018 12:51 PM To: [email protected] Subject: Re: [BITX20] Thunderbolt and lightning, very, very frightening me ?
Looks like good advice.
The Polyphaser stuff has been around for awhile, and is designed for this kind of use. If you are in an area that sees lightning, you want a proven system. And you want to follow all instructions closely. Here's a discussion on eham that might put the fear of god in you. ? ?? Unfortunately, those whose budget just barely covers a Bitx40 might decide to go without. This one is good to a kilowatt, $68.99 plus shipping.? ? ? ?? Plus multiple ground rods, #6 copper wire, ... Gets worse if you have multiple antennas. One of these gas discharge tubes might do it for cheap: ? ?? but I'm not about to hazard a guess as to what's appropriate around lightning. And that eham discussion suggests the Polyphaser thing is more than just a GDT, has some caps in it too, and I have no idea what else.? Anybody with a cheaper solution they feel is adequate for QRP levels? I'm sure lightning could find a way to bite us here. But being off grid with no landline phone has its advantages. While in college I spent summers on BLM fire crews, once spent a couple weeks in a tower spelling the regular lookout.? They take lots of lightning. Had a special stool you could cower on in the center of the floor during a storm, big honking glass insulators on the bottom of the legs. Just sit there and watch the sparks fly about within the cabin a few feet away. And then when it was over, the VHF radio still worked. Jerry On Tue, May 8, 2018 at 08:24 am, ajparent1/KB1GMX wrote: Doug,? A ground rod outside (preferable a 8ft or longer...) with a Polyphaser arrester at the top of it |
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Verrrry good information.
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Can you point to a recipe with schematic and parts fully specified? If the antenna does take a direct hit, does it destroy the device? I find it hard to imagine that a GDT can take everything a lightning bolt has to offer. Or that the series caps could possibly survive. Jerry On Tue, May 8, 2018 at 12:18 pm, Gordon Gibby wrote:
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Ah, good.
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I may have to order some parts. There's lots of radio towers that somehow take direct hits. My best guess is they make sure they have a very attractive lightning rod up above any antenna. Might work for a VHF antenna, not so much an 80m dipole. Does any of this stuff protect from a direct hit to the antenna? Jerry On Tue, May 8, 2018 at 12:25 pm, Gordon Gibby wrote:
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Matthew Stevens
Does any of this stuff protect from a direct hit to the antenna?Nope.. it's intended to bleed off static charge from nearby strikes and in the air during storms - just like a lightning rod. There are ways to handle a direct strike. They aren't within the capabilities (or budget) of a normal amateur. And they're not even foolproof. I have a friend who owns a commercial tower company. He has on his desk in his office a set of spark gap balls from a tower he worked on, hollow galvanized spheres about 1/2"-3/4" wall thickness and maybe 4" in diameter. Each of them is blown in half from jumping a direct strike to ground off the tower... He also has a collection of waveguide in his shop that has holes in it every 3-4' where lightning hit the tower, and some of the energy was directed down the waveguide. It burned through the side of the channel every so often as it traveled down. That was an expensive replacement So, I have polyphasers clamped to ground rods where the feedlines enter my shack. They do a great job of bleeding off static, maybe even employing the antenna as something like a lightning rod and dissipating the charge from the air before a strike even occurs. But when I'm done operating, my radio is disconnected from the wall outlet and the antenna, and the feedline from the antenna is left hooked to ground. I don't trust myself enough to take chances with lightning, at least not here in central Florida. 73 - Matt nj4y On 5/8/2018 3:38 PM, Jerry Gaffke via Groups.Io wrote: Ah, good. |
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M Garza
Here is an interesting video from a UK ham who went through a lightning strike.? Quick summary, Unplugged equipment was damaged also. Marco - KG5PRT? On Tue, May 8, 2018, 3:16 PM Matthew Stevens <matthew@...> wrote: ?> Does any of this stuff protect from a direct hit to the antenna? |
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Gordon Gibby
开云体育"Verrrry good information.
The schematic & some of the parts information is in this article: ? See page 3 for suggestions for the Gas Discharge Tube.
Use .01 uf ceramic capacitors.? 1 Kv types and two of them in parallel.? ?Were cheap on Digikey. I would recommend 100K 1 or 2 watt composition or thin/thick film resistors in parallel with both the antenna and the gas discharge tube.
Or just forget the series capacitor and just put one 100K across the Gas Discharge tube.
If there is a direct hit all of this is likely to be vaporized or toast. I would suggest that you replace the gas discharge tube every few years depending on how active your area is.? ?an expert to whom I spoke indicated that repeated small discharges slowly raise the break-over voltage of the device.? ??
i'm in a very high activity area so maybe I should do it every 2 or 3? years.? ?You might be in a very minimum area and only every decade or so???
Who knows.
Anyway, while I have had friends have radios destroyed,? I have never ever had one destroyed.? ?
Hope this helps.? ?The important thing is NOT the metal construction, instead the important thing is the SIZE OF THE GRouND WIRE and how good your ground is, and a pretty good ground wire between the two SO-239's also!!!!!!? ? ?ideally these things should
be placed on the OUTSIDE of your house.? ?What I have tended to do since my radios are on the second floor, is to position a ground wire right near the coax (you can wrap that or even connect it to the shield) or "near" the balanced line......? ?to create
a spark gap that the lightning will jump THERE.
Coax jumps around 5 kV.??
Hope all of this is helpful!! Gordon kx4z
From: [email protected] <[email protected]> on behalf of Jerry Gaffke via Groups.Io <jgaffke@...>
Sent: Tuesday, May 8, 2018 3:30 PM To: [email protected] Subject: Re: [BITX20] Thunderbolt and lightning, very, very frightening me ?
Verrrry good information.
Can you point to a recipe with schematic and parts fully specified? If the antenna does take a direct hit, does it destroy the device? I find it hard to imagine that a GDT can take everything a lightning bolt has to offer. Or that the series caps could possibly survive. Jerry On Tue, May 8, 2018 at 12:18 pm, Gordon Gibby wrote:
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I've worked with shelters and all for land mobile.? They are ringed underground with rods and wires,
same with surfaces and corners and then everything that goes into teh building is though a copper plate with with polyphasor or similar before it geto to anything inside. IT's bonded to the tower with copper straps usually wide like 4 to 6 inches and more than one.? They can take a direct hit. Many years before a AM BC station.? You have the filed with the 120 wire ground plane, ground rods most 12ft abound.? Tower is up on insulators for base feed but thereis an arc gap from each leg spaced maybe 3 inches? the feed sire goes to the load coil in the doghouse next to the base and that has straps to ground for RF and sparks.? ?The feed lines are arranged to arc ro ground before the TX shed.? Been there during a storm, the sparks are impressive and frightening.? About 1 in 10 caused the big 5kw RCA to shut down usually a reset of breakers was all it took to start running the heaters(tubes) then B+ and the modulator.? About twice a year the power company feed was a problem so we were 1KW off genset backup. Me I've gotten hit twice one direct to the house antenna, fried the #6 wire to BBs and much of the electronics in the house.? Second time it hit a pole down the hill before it went underground about a mile away the surge got me, mostly minor. The big thing is to protect so two things happen.? You do not burn the house down. Your insurance then will cover any damage (or they do their best to weasel out). Complying with NEC code is more for the prevention of insurance issues. Call me pragmatic.? Prepare for the worst be, happy if it doesn't happen. Allison |
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Gordon Gibby
开云体育?Allison --- thanks, that is GREAT information..... From: [email protected] <[email protected]> on behalf of ajparent1/KB1GMX <kb1gmx@...>
Sent: Tuesday, May 8, 2018 4:53 PM To: [email protected] Subject: Re: [BITX20] Thunderbolt and lightning, very, very frightening me ?
I've worked with shelters and all for land mobile.? They are ringed underground with rods and wires,
same with surfaces and corners and then everything that goes into teh building is though a copper plate with with polyphasor or similar before it geto to anything inside. IT's bonded to the tower with copper straps usually wide like 4 to 6 inches and more than one.? They can take a direct hit. Many years before a AM BC station.? You have the filed with the 120 wire ground plane, ground rods most 12ft abound.? Tower is up on insulators for base feed but thereis an arc gap from each leg spaced maybe 3 inches? the feed sire goes to the load coil in the doghouse next to the base and that has straps to ground for RF and sparks.? ?The feed lines are arranged to arc ro ground before the TX shed.? Been there during a storm, the sparks are impressive and frightening.? About 1 in 10 caused the big 5kw RCA to shut down usually a reset of breakers was all it took to start running the heaters(tubes) then B+ and the modulator.? About twice a year the power company feed was a problem so we were 1KW off genset backup. Me I've gotten hit twice one direct to the house antenna, fried the #6 wire to BBs and much of the electronics in the house.? Second time it hit a pole down the hill before it went underground about a mile away the surge got me, mostly minor. The big thing is to protect so two things happen.? You do not burn the house down. Your insurance then will cover any damage (or they do their best to weasel out). Complying with NEC code is more for the prevention of insurance issues. Call me pragmatic.? Prepare for the worst be, happy if it doesn't happen. Allison |
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Gordon Gibby
开云体育I understand that, it’s just that my station has to run 24/7/365. ? (2 WINLINK gateways). So we do the best we can. ? In the 19 years we’ve lived here, the trees have now grown considerably higher than the house, and the 3-story house has $thousands of dollars worth of lightning rods/ground wires. ?The antennas are lower than the trees and not really that much higher than the house. ?One of them has a good ground path before entry into the house, the other not so good. ?In the 19 years, I think the only thing that ever even seemed to have been harmed, was a DSL modem connected to the telephone lines. ? I’m not even sure it was harmed. ?Once the solar power system got screwed up by a powerline hit, but it worked fine after being reset. ? I have two complete sets of transient control systems on every input or output of the solar power system.I can’t say enough how I think the best thing you can do is grow pine trees taller than your antennas.
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Matthew Stevens
开云体育Back in 2012 my next door neighbors maple tree was hit. It ran down the tree into the ground. To the north it ran along the galvanized water line where it blew the water meter and a chunk of the curbing across the street. To the south, it ran towards the house, jumped across the 8’ wide concrete porch into the DOORBELL BUTTON.... blew a 4” hole in the concrete block wall, burnt all the interior house wiring (like, black scorched marks on the walls), shattering light bulbs and burning up light switches etc. burned the breaker panel out behind the house. It went from there into the phone line... to the pole in the street where it blew the cover off the 1940s era lead telephone junction box (found that down the street about 30yards).Went into my house via the phone line from that pole, tripped GFCIs in the back of the house, broke two light bulbs in the ceiling, and then through the cable line fried the cable modem-and literally scorched the on-board NIC off the motherboard on my fileserver which was connected directly to the modem/router. So yeah... I have a healthy respect for lightning :-) My radio in the front of the house was unplugged at the time - and fine. Not to say that a nearby strike can’t cause issues even with an unplugged rig. But I think it’s better than leaving it plugged in. At least it makes me feel better even if it’s not accomplishing anything haha. 73, - Matthew nj4y On May 8, 2018, at 16:53, ajparent1/KB1GMX <kb1gmx@...> wrote:
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Ghericoan