Question on "Going to Ground" aka throw the coax out the window !!

[K4IMZ]

I have always been respectful of T-storms and Lightning.. Maybe it was watching as an arc hit the top of the old 250' BCB tower during a mostly clear day in July some years ago. You never forget the feeling of hair raising on the back of your neck as you are working about 3' from the feed coax...(working on the xmitter cooling.. those bc5b's really put out the heat)

 anyway,  as I have always gone outside and disconnected my ham coax and ground line when not on the air, my ability to physically move out and around the house to the disconnect point is decreasing..

other than a dx engineering control box, which will set me back a couple weeks of dr. visits.... does anybody have a disconnect switch diagram ,???

 I have seen various ideas on other sites from sparkplugs to slingshot the coax out the window / "sarc"..

What do You Use ??

As Always, any and all input appreciated..

 

[WA1GFZ]

I use a bird switch to open coax. Sometimes I throw a pipe over the open wire line to direct a bolt to ground. It is always best to break the connection to the house when you can.

[ke7trp]

Agreed, A big disconnect switch is probably the best. The kind that Grounds the lead to a seperate earth ground. If all else fails, Unhook the coax and put the end in a tall/thick Glass Jar.  I used to use this method years ago and serveral times saw the voltage dancing in the jar.

C

[John K5PRO]

When I was a novice, years ago, the tree that held one end of my half wave dipole got a direct hit. I was in the room, the coax was disconnected and lying on the floor. I saw a big loud spark simultaneously jump from the PL259 to a 120 VAC outlet, about a foot away. The noise was deafening, from the direct strike outdoors. There was smoke and when it was done, the entire ground on the Romex under the house had burn marks at every staple and the breaker was ruined. The RG58 to the center insulator was gone, melted, as was the antenna wire.

[WB4AIO]

I have always been respectful of T-storms and Lightning.. Maybe it was watching as an arc hit the top of the old 250' BCB tower during a mostly clear day in July some years ago. You never forget the feeling of hair raising on the back of your neck as you are working about 3' from the feed coax...(working on the xmitter cooling.. those bc5b's really put out the heat)

 anyway,  as I have always gone outside and disconnected my ham coax and ground line when not on the air, my ability to physically move out and around the house to the disconnect point is decreasing..

other than a dx engineering control box, which will set me back a couple weeks of dr. visits.... does anybody have a disconnect switch diagram ,???

 I have seen various ideas on other sites from sparkplugs to slingshot the coax out the window / "sarc"..

What do You Use ??

As Always, any and all input appreciated..

 

One technique that gave me reasonable confidence in thunderstorm season was this:

I used ladder line, and it came in under an easily-opened window sash. I used large banana-style plugs to connect it to my tuner.

I would open the window, disconnect the feeders from the tuner, then throw them out the window so they were lying on the ground 15 feet or so from the house. (I would love to have been able to do essentially the same thing with the AC mains feed and grounds too, but it would have been too big a project for my available time and budget.)

Of course, to do that, you do have to go outside to re-connect.

Any single relay or switch-based disconnect is going to have the possibility of arcing across the contacts in the case of a hit or large surge. Having the feeder shorted to ground as well as disconnected from the house will help make an arc to the shack feeder less likely, of course. But those contacts are still inches apart and currents can be induced. Having two disconnects in series, one near the house and another closer to the antenna would add some measure of confidence in my view.


With my best,


Kevin, WB4AIO.

[W1RKW]

If all else fails, Unhook the coax and put the end in a tall/thick Glass Jar. 

Seriously??? 

I can't imagine a glass jar suppressing a direct hit that drops from 30,000 feet. Lightning will laugh at a jar. 

I've had the experience of lightning coming down a disconnected feedline (not a direct hit but induced) and it's the last time I care to see it inside the shack.  My feed lines are disconnected outside and moved away from the connection point.  Got to much to lose on a chance.

 

[W2PFY]

Got to much to lose on a chance.

The non funny thing is, I know of a number of our buddies that never unhook their antennas and so far, nothing happened. I struggle knowing this every time I visit those guys.

[ke7trp]

Oh no.. Not a direct hit..  Direct hit, all bets are off!  

Putting the coax into a glass jar does two things,  One, It saves your gear.  Its not connected to that expensive radio anymore.  Two, It stops the voltage at the end of the coax from arcing to anything else in the room such as your wall outlet box.

I lost many a reciever with a vertical I had. This antenna would show big arcs from the tip out.  Sounded like a bull whip. placing the coax in a jar worked to save my gear.

On my wire, I built a box holding two chokes that go to ground. This stopped the arc over.  I used to get big arc's from the terminals on the tuner to chassis. During storms.

C

[Todd, KA1KAQ]

Balanced Feeders are the easiest to ground, simply install one of those big copper knife switches running the aerial to the center (handle) terminals, hook one side to the rig's feedline and the other to ground. When you're done using the rig, 'throw the switch' to ground. This should bleed off any charge before it can build up to a dangerous potential.

Coax is more difficult. A good switch that grounds all positions that aren't selected should do about the same thing. Not sure of the Bird of other heavy duty switches do this or not. If not, you could dedicate one switch position to a dead short/grounded stub and switch to that when not in use.

I'm one of those guys who never disconnected the feedline with any regularity due to living in a low-lying area and a part of the country with few T-storms. Now that I'm in Fo' land, it's a different ballgame. We get a lot of storms and they can be brutal. Coax gets disconnected all the time now, until I can find a better alternative. It is a major PITA but more sensible than rolling the dice.

[ke7trp]

There are lots of solutions including polyphaser.  Just dont run in the shack during a T-storm and start disconnecting things. A radio is not worth your life.

C

[Todd, KA1KAQ]

Nothing to do with running the shack during a storm, Clark. Simple protection for the equipment when it's off and not in use, something other than disconnecting cables and throwing them out into the rain is what I was referring to.

[ke7trp]

Protection for ladder line antenna is going to be two large chokes that ground the antenna.
Protection for coax fed antennas is going to be a box with two coax connectors or a coffee can and single choke with Center to Ground.

C

[WB4AIO]

Protection for ladder line antenna is going to be two large chokes that ground the antenna.
Protection for coax fed antennas is going to be a box with two coax connectors or a coffee can and single choke with Center to Ground.

C

That's good protection from DC charges that can build up when fronts move through. But it's no protection at all from nearby hits that induce high frequency energy in your feeder.


With every good wish,


Kevin.

[W1RKW]

To each his own but to me no matter what the severity of a lightning storm, disconnect and remove the feedline from the residence/shack. I'm not trusting of switches and other grounding apparatus.  Protecting the radio gear is one thing and protecting the structure is another.  And protecting life and limb is tops.

Like my previous post, I've seen lightning come down my feedline and arc over to an object in the shack that was at least 12 inches away.  I've seen it come out of wall sockets and down my parents disconnected TV antenna when I was JN living there. I've even been wacked and put on my butt by induced voltage in my garage when touching a large metal object.  I've been hit in the chin when talking on the phone. Thanks but no thanks. Won't take much to stop ones heart or start a fire. Got to much respect for Ma Nature.

[Mike/W8BAC]

Clark,

I remember when you had that static discharge problem a few years ago. I see you added the coils and you did a nice job with that box as well. You might look into a wall feed through that isolates the wire from the wood.

Kevin/WB4AIO put it best. Those inductors are great for static electricity but will do nothing to stop a lightening strike for open wire or coaxial feed lines. If your not going to disconnect or ground you need an arc gap engineered for the job.

If you took a hit now those through wall feeders would become through wall flame throwers.

Mike

[ke7trp]

To each his own.  The coils do help in a storm and they saved my gear over and over.  Will they take a direct strike? No. Nothing will.  You are done either way in a direct hit. However, Without the coils as a storm aproached the house, I would get arcs from ladder line insulators to the ground stud on the tuner or to the tuner case, This knocked out recievers.  With the coils, This arc never happens. The voltage goes right to ground. 

So the coils are a great way to protect your gear, reduce static and popping on your reciever. But nothing short of a poly phaser is going to help with a direct hit. Even then, I have heard of people loosing gear.  The only real thing to do is to use your ARRL insurance and get new gear for free (if you are an ARRL member).

C

[WB4AIO]

To each his own.  The coils do help in a storm and they saved my gear over and over.  Will they take a direct strike? No. Nothing will.  You are done either way in a direct hit. However, Without the coils as a storm aproached the house, I would get arcs from ladder line insulators to the ground stud on the tuner or to the tuner case, This knocked out recievers.  With the coils, This arc never happens. The voltage goes right to ground. 

So the coils are a great way to protect your gear, reduce static and popping on your reciever. But nothing short of a poly phaser is going to help with a direct hit. Even then, I have heard of people loosing gear.  The only real thing to do is to use your ARRL insurance and get new gear for free (if you are an ARRL member).

C

Your coils are beautifully done (as is your whole setup, very professional), and do totally take care of the static charge problems. They look very much like the static discharge coils I used in AM broadcasting.

All I am saying above is that, if there's a direct hit and the end of your feedline is outside -- 15 or 20 feet from your house where you threw it -- you're a lot better off.

And the same holds true for nearby strikes.

If I ever build a new shack from scratch, in addition to total antenna disconnect and far-removal ability, I'd like to be able to do the same thing with the AC power and ground connections when electrical storms are imminent.


With my best,


Kevin, WB4AIO.

[flintstone mop]

I have heard stories from Discovery channel about lightning coming outta nowhere on a cloudless day from an approaching T-storm.
Seems mostly near the Left Coast, AZ and elsewhere

Fred

[KA1ZGC]

Like the old adage says: there's no such thing as lightning protection, there's only mitigation.

That being said, anything is better than nothing.

The tricky thing about lightning discharges is that they're not DC by any definition. They're pulse emissions of gargantuan amplitude. Spectral analysis of EMI radiated by a lightning strike shows energy throughout the HF spectrum, like a giant blast of white noise, often stretching right up into VHF and UHF, depending on the duration of the pulse (the longer the pulse, the lower the frequency of the half-cycle it forms).

A very different phenomenon is a steady buildup of static electricity in advance of an approaching thunderstorm. This is REAL fun to witness first-hand high atop HLR mountain in a thunderstorm. You'll be sitting there, minding your own business, when suddenly a rhythmic "pop pop pop" can be heard in the receiver. Step outside, and you'll hear the phase-reverse relay of the wire array going "bap bap bap". Then you know there's a storm about 20 miles away making its way towards you.

Eventually, there'll be a loud "crack" emanating from the blockhouse, and the rhythmic "bap" will cease. A few seconds later, thunder will roll in from some distant lightning strike. Ten or fifteen seconds after that, the rhythmic "bap" will start again, getting louder and louder until the next lightning strike.

That's most likely what was causing Clark's troubles prior to installing the chokes, and they're an effective solution for bleeding off that DC buildup prior to the storm discharging itself to ground by way of a lightning strike. The storm itself is only the tip of the electrostatic iceberg, the field itself can stretch for 20+ miles in all directions. An antenna of sufficient height to couple into that field will build up a charge from it. Likewise, an antenna of sufficient length will induce a charge from the passing EMP wave, causing one end of the ant to suddenly soar to a very high voltage relative to the other end.

Great fun for the whole family!

My $0.02.

--Thom

[WB4AIO]

[...]

A very different phenomenon is a steady buildup of static electricity in advance of an approaching thunderstorm. This is REAL fun to witness first-hand high atop HLR mountain in a thunderstorm. You'll be sitting there, minding your own business, when suddenly a rhythmic "pop pop pop" can be heard in the receiver. Step outside, and you'll hear the phase-reverse relay of the wire array going "bap bap bap". Then you know there's a storm about 20 miles away making its way towards you.

Eventually, there'll be a loud "crack" emanating from the blockhouse, and the rhythmic "bap" will cease. A few seconds later, thunder will roll in from some distant lightning strike. Ten or fifteen seconds after that, the rhythmic "bap" will start again, getting louder and louder until the next lightning strike.

[...]
The storm itself is only the tip of the electrostatic iceberg, the field itself can stretch for 20+ miles in all directions. An antenna of sufficient height to couple into that field will build up a charge from it. Likewise, an antenna of sufficient length will induce a charge from the passing EMP wave, causing one end of the ant to suddenly soar to a very high voltage relative to the other end.

Great fun for the whole family!

My $0.02.

--Thom

Thom, that was a very dramatic description; thank you.

I have been standing in a field of four AM broadcast towers, supported by multiple guy wires broken up with hundreds of big ceramic insulators. Once, as a storm front approached, all these huge insulators arced over nearly simultaneously with frighteningly loud snaps. That was dramatic too.


With good wishes,


Kevin, WB4AIO.

[K4IMZ]

Thanks to everyone for the replies and suggestions.  I agree in a direct hit all bets are off.

 my concerns are protection from a nearby strike (static charge i think ) since here in the mtns of NC a storm can pop up in minutes.
 For that I believe I'll go with polyphase or I.C.E. in line with coax.

I'm going to use an old trick of monitoring an am BCB radio on an unused local freq so static crashes will be audible, kinda like an early warning system.. hihi..

I have no clue as to the building of an effective spark gap , nothing I would trust myself, dwelling or rigs to a pair of NGK's.

so for now , it will remain.. " throw 'em out the window" 


K4IMZ
 

[W1UJR]

Great amount of reference info on the posts, a very good topic!

Direct strike, you're done, that lightning which leapt several thousand feet from sky to ground, or ground to sky, laughs at the average ham grade "lightning arrestor". As Tom so succinctly put it, all one can do is mitigate.

Here is a lightning strike on a tree about 50 feet from my ham shack in 2006 --> http://www.w1ujr.net/lighting_strike.htm
Details in the webpage, suffice to say that the damage was considerable, but I was very fortunate in the sense that no structural damage resulted.

Perhaps even more insidious is the buildup to the storm, or even snow static, again reference Tom's comments about HLR mountain.
I used to routinely see my feedline connection snap, crackle and pop with an approaching lightning storm, now I short them together.
My elmer, W2UJR SK, used to talk about "snow static", not something you often hear about today.
While that this may not harm most hollow state rigs, with solid state, I would not want to take a chance.
Again, another link, this time during a winter snowstorm at my QTH in Maine -->> http://www.youtube.com/user/W1UJR#p/u/8/_7HSTPl6e-I

I just don't take a chance, on the video you'll see banana plugs and jacks to disconnect all in the shack, simple and clean for balanced line.

[K4IMZ]

My elmer, W2UJR SK, used to talk about "snow static", not something you often hear about today.
While that this may not harm most hollow state rigs, with solid state, I would not want to take a chance.

I was told of "Snow Static" by K4HU (SK) who would take hours and explain theory to a newbie like me.  I kick myself for not recording or writing down, what years later , are fond memories, as now I try and remember where I left my glasses.

Also , elmer advice from Ken WA4BVW and Gene K4EEV, both who worked on Mt Pisgah (WLOS-TV) and the stories of lightning strikes there, convinced me to disconnect and get the coax away from the shack..  But now as I'm older and moving less, I was looking for a new Snake Oil.. alas, the rules are still the same...

[W2PFY]

I wus just thinking that if a person were to use banana  plugs for the open wire type feeder, a spring loaded device of some sort could be put into use to disconnect the feeders if you let the storm get too close, and were afraid to unhook it by hand. Press a button inside and Kazan, the feeders shoot off into the woods.  

In the case where coax is used, a quarter pound of TNT could blow the line apart by a push of a button or perhaps the lighting bolt would set off the explosive and the resulting pressure wave would create a vacuum where the electrical path would be interrupted.

The second method would only be recommended for you country boys with acreage  

[W2PFY]

Please remove this. tnx