[ADXA] Antennas & lightning

Sun Jul 13 16:28:35 EDT 2025

Hi Jussi,
You will find two camps on disconnecting vs staying connected.  I come from decades of being the broadcast and cellular systems.  They couldn't disconnect as they were the cash registers of the companies I worked for, hi.  If they were unplugged, they were not making money and didn't provide valuable emergency service.  So my mind is a bit cloudy compared to most folks!

Both systems had the very best grounding systems, bonding, isolation, etc.  Like Chuck said, there seems to be sites that get hit more than others.  I helped maintain over 200 sites and some would never get hit or seem not to.  Others, were a bit more problematic.

One time I was working at a cell-site near Mountainburg AR.  It was also a pretty big microwave hub and while working on some microwave gear heard a huge WHAP.  I also thought I heard something whiz by my head.  I didn't think anything more about it as we were still on the air!  Later when sweeping the antennas I noticed one of the center pins missing from a 1-inch ¾ hard line.  Then I remembered the WHAP and whizzing sound.  I went back to where I was standing ( a good 20 feet) and there was the missing center pin stuck in wall of the cell site building.  A few inches closer to my head, well I would have been seriously injured or worse.   If you could see how some of those sites are built, you would probably be a little impressed with the lightning protection.

That particular building was the old design from Contel.  We had others such as the ones designed from Alltel, (BTW those were the worse for lightning)!  Same gear, but put together differently.  Then much later we had what we called the Polyphaser design.  IMHO, both PP and the Contel designs were both pretty good!

I could talk for hours on this subject.  In the end, it all boils down to the individual.  If you are a contest station, I doubt you are going to be in the disconnecting camp because if you are off the air, you are not making contacts.  You in it to win or to make a good score.  In you are in the disconnecting camp, usually the ones that value their gear a little more and don't want to go through repairs or insurance claims.  In others words how much are you willing to put up with?  Both have advantages and disadvantages!

I didn't check this out, but I think this is the right link?  This could be a good place to start:  https://northgeorgiacommunications.com/wp-content/uploads/2022/05/Motorola-Standards-and-Guidelines-for-Communication-Sites-R56-Manual.pdf
68P81089E50.book - MOTOTRBO™<https://northgeorgiacommunications.com/wp-content/uploads/2022/05/Motorola-Standards-and-Guidelines-for-Communication-Sites-R56-Manual.pdf>
Disclaimer While reasonable efforts have been made to assure the accuracy of the information contained in this document, Motorola, Inc. assumes no liability resulting from any errors or omissions in this document, or from the use of information obtained herein. The information in this document has been carefully checked and is believed to be entirely reliable. However, no responsibility is ...
northgeorgiacommunications.com
Most folks seem to think it is the big direct hits that do all the damage!  If you look at a disconnected cable during a light rain or even snow you will see the blue ball of fire from static discharges!  Notice I didn't say storm here, just light rain or snow can do it at times!  Depends on how the particles are charged if you see this or not.  Sometimes you will and others you will not.  No matter the radio, they cannot take that kind of static discharge.  Inside most radios these days, I have seen everything from surge protectors to small SMD light bulb in series to help protect the front end.  Kenwood use to call their surge protectors, Thundersurge protector in their service manuals!  They later went to the small SMD blubs in most radios as they were much cheaper.  Most of the time the damage is done to other great before it gets to the radio, thankfully!

You also have to decide on what is a good feedline protector.  Some have DC ground and others don't, the others have an arch gap.  Both have gas surge and arch protectors.

If your station is not mission critical.  I would still do the very best grounding, bonding, and isolation.  Then disconnect when you are not there.  I know some stations are so big this would be a huge pain in the backside, but in my case, it only takes a few minutes to do and re-hook up when the storm passes.

I saw one remote station using a mechanical homebrew device to physically disconnect the feedlines.  It was brilliant, but I am lazy and never built one of my own.

Like I said, it all depends what you are willing to gamble on.  I am not much of a gambling man so I chicken out more than some, LOL.

The above is just a personal opinion only.  You bring up this subject to a club meeting, it is much like discussing politics or religion!  I understand both sides of the razor blade and can defend both, hi.

Like with anything in ham radio your mileage will vary!

73 de jay/w5jay..

________________________________
From: adxa-bounces at mailman.qth.net <adxa-bounces at mailman.qth.net> on behalf of Jussi Eloranta <eloranta at aa6kj.hopto.org>
Sent: Sunday, July 13, 2025 2:34 PM
To: 'ADXA' <adxa at mailman.qth.net>
Subject: Re: [ADXA] Antennas & lightning

Hi,

Thanks everyone for sharing the info! Very helpful!

Just to add that the network connection to my station is through optical fiber (two modems and a short piece of fiber) just to make sure there is no electrical contact. The station side modem gets disconnected from AC whenever the station is disconnected. My shed is made of metal (Faraday cage) and I must bring the net in using ethernet cable (from outside WIFI repeater). And my QTH is located high up, so lightning strikes are frequent. That reminds me, I am told that we are "hill people" - I guess that is a nice way of saying hillbilly :-)

Since my station ground is bonded to the AC ground, I will add a connector that allows me unplug the ground easily as well. This is the likely reason my K4 got hit. And Adding more copper for better ground is on my TODO list now as well. As usual, there is no free lunch :-(

But there is not much that can be done if it is a direct hit. In such case I just hope that my shack does not evaporate...

All right, now it is time to pack!

Jussi (aa6kj)

ps. Bill, if I run into Martti, I will certainly say hi to him from you.

On 7/13/25 13:12, k5ur at aol.com<mailto:k5ur at aol.com> wrote:
I've had serious damage from lighting over the years and some of you will remember some of my stores.... holes in the wall, busted walls sheetrock, ceiling caving in and endless equipment damage.

I  have a massive ground system under these towers. Miles of wire, yet sometimes damage from a direct hit is hard to mitigate.

I recall one time when lightning hit a tree just on the other side of the wall in the radio room. I suspect it hit one ofthe towers, too. The 200 ft tower is lightning rod. Anyway, I had a pole peg transformer in one of my homemade power supplies sitting against the wall, so there was probably 8 feet separating the transformer and the tree. Everything was disconnected yet the induced voltage on that pole peg caused an explosion in the radio room. Arcs everywhere.

I disconnect every line when a storm is coming. Nothing is connected, not even the ground. Nothing. Back in the day with tube radios, you could keep the ground connected but not today with these fancy radios. My radios are as if they are sitting in the floor in the middle of the room with nothing connected to them.

All coax lines and rotor cables, disconnected, all cables to radios, amps, accessories, all disconnected and nothing attached. And that goes for the AC lines, too. Living at the end of a distribution line invites the stuff to travel to a termination. I've had AC outlets blown to bits leaving a hole in the wall.

Disconnect everything!

73,
Rick - K5UR

On Sunday, July 13, 2025 at 10:23:18 AM CDT, J Ferguson via ADXA <adxa at mailman.qth.net><mailto:adxa at mailman.qth.net> wrote:

Jussi,

Lighting is a fickle beast. The energy potential in lighting far exceeds the rated handling capability of polypahsers, and despite our best efforts to ground and control the path of a strike the risk of it finding it’s way to my equipment is too great.
I always disconnect my attendants and radios (when I am in a position to do so) to reduce the likelihood of a direct of nearby strike causing equipment damage. My antenna coax is place the open end in plastic lawn and garden waterproof extension cord covers when disconnected. This provides me (perhaps a false sense of security) with trying to make sure the antenna and coax being in a float state for the energy of a strike to travel. It also helps to keep me from having the coax accidentally being kicked or moved and creating a possible ground path.

What I use for covering the coax: https://www.lowes.com/pd/Twist-and-Seal-0-5-ft-Plastic-Cord-Organizer/1000132801

Sounds like your shack is outside your home, have you thought about setting up a remote disconnect system?

Others thought’s on this topic?

73,
J Ferguson
N5LKE

On Jul 13, 2025, at 9:58 AM, Jussi Eloranta <eloranta at aa6kj.hopto.org><mailto:eloranta at aa6kj.hopto.org> wrote:

Hi,

The weather has been pretty rough at least here in the NE corner. Lightning on and off on almost all days. I have been running back and forth between the house and the shack disconnecting and reconnecting antennas & power. The weather forecasts have been pretty useless with these storms. They appear quickly and are gone quickly.

My question is as follows. With proper grounding and polyphasers on coaxes (+ surge protectors on power), do you guys disconnect antennas & power during storms? In CA lightning is rather rare and this was not an issue over there. I feel that here I have the radios disconnected most of the time! And my K4 died mysteriously during a recent storm with only the ground connected. It is possible that lightning can get in through the ground too... Fortunately Elecraft was pretty quick to fix it.

Jussi (aa6kj)

PS. I am headed to Finland to attend the annual SRAL summer meeting. Hopefully the weather is calmer there... Great to see some old friends over there.
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