Thunderstorms and Antennas

[Realtor MA]

Last night as the storm passed through I was wishing that I had disconnected the coax from my radio. I intended to do it after I had finished up in the shack earlier that night. I didn't dare do it during the storm as I figured that was the last thing I wanted to be messing with. For HF I have wire antennas. Does anyone have any opinions as to how susceptible these are to a lightning strike?

 

[Lucas McCain]

The likelihood of a direct hit on your antenna depends on a lot of factors including hight above terrain, nearby objects and the like. The real danger is the EMP from a nearby strike inducing high voltage on your antenna and thereby the feedline. To be safe, you should ground both sides of your feedline to a good earth ground. This connection is intended to provide a low impedance conduction path to ground. I remember a long time ago, I used to disconnect my PL-259's and set them on the painted radiator cover during a thunder storm. One night, I woke up to loud cracks and flashes soon to discover that every time I saw a flash of lightning, the coax would arc right through the paint to the metal radiator. From that point on, I have always grounded all my antennas when not in use.

Some antenna switches ground the unused antennas automatically but I am cheap and use just a simple SO-239 that I have soldered both sides to a braid and connect it to my station ground (ground rod)

This picture shows the SO-239 connected to a T fitting and has both antennas screwed into it, the braid goes to the single point station ground stud. This will not prevent damage from a direct strike, not much will but it will safely protect your station from damage from EMP energy.

 

[n1oty]

Use high quality coax, use polyphasers and ground the coax shields properly like the commercial guys do. I no longer use the cheap coax. I use Andrew Heliax and the real Andrew grounding kits.

 

[Realtor MA]

Thanks guys. I believe my antenna tuner grounds the antenna when it's not in use so hopefully that does the trick. I'll look at some additional measures too.
Right now my vhf/uhf jpole is totally unprotected so i should probably work on that first.

 

[Zappa]

In the old house where I had a base station, I used a heavy duty coax switch like this one:

The antenna was fed into the single end.
The "A" side went to the triplexer and the "B" side right to ground.
When the radios were off, I always switched to the "B" side thus diverting any potential lightning strike dierctly to ground. I know this saved my radios at least once.

 

[drgrant]

Anything expensive I unplug it from power and coax.

Anything cheaper (like my 2M rigs) I just leave them plugged in all the time- if they blow up they blow up. Never had it happen.

The reality is if you want to do real full blown lightning suppression/mitigation, there is a right way to do it but it is obnoxiously expensive and there is a lot of engineering involved.

-Mike

 

[Realtor MA]

In the old house where I had a base station, I used a heavy duty coax switch like this one:

The antenna was fed into the single end.
The "A" side went to the triplexer and the "B" side right to ground.
When the radios were off, I always switched to the "B" side thus diverting any potential lightning strike dierctly to ground. I know this saved my radios at least once.

This is probably what I'll do but can that switch really isolate the voltage from a direct hit?

Anything expensive I unplug it from power and coax.

Anything cheaper (like my 2M rigs) I just leave them plugged in all the time- if they blow up they blow up. Never had it happen.

The reality is if you want to do real full blown lightning suppression/mitigation, there is a right way to do it but it is obnoxiously expensive and there is a lot of engineering involved.

-Mike

Yes, I could live if my 2m rig gets blown up. I would be bummed if my amp or HF rig gets zapped.

 

[C-pher]

I suck...I still haven't even drove two ground rods in yet. I keep rememebering every time we have a T-Storm.

 

[radioman]

I live on a hill. All of my antennas are the highest points around. I've had several strikes since I've been here. I had one follow my cable TV wire inside the house. I saw and heard the ark!! I keep all my radios unplugged not switched off but unplugged unless I'm using them. If you rely on a switch? keep in mind the arc just jumped several miles from the sky I don't think it's going to stop at the 1/4 inch gap in your switch? I keep my rigs unplugged just in case I'm out of the house and a storm hits. I'm not risking multi thousands of equipment because I don't want to take the 5 seconds to unplug!

 

[Realtor MA]

Maybe a dumb question but does anyone offer insurance for such disasters?

 

[Harleynut]

My Elmer from back in 1976 was a old time ham he had his shack set up in attic. Outside the window he had a box with the coax going in. Every time it was going to storm he would disconnect and throw the wires out on the lawn outside and away from the house. His method was crude but effective.
Later I had so many wires going into my own shack I could never disconnect and would just leave the room and make sure insurance was paid. If the lightning bolt has enough energy to jump long distance it can jump the contacts in the switches.
One other thing to keep in mind is that most of the lightning is on the leading edge of the storm ahead of the rain. If you wait for the rain its to late.
At one time I had a house with a hill about 50 ft tall behind the house and then had 100 foot tower with about 25 foot of antennas above that. With all the extra long wires and a 40/75/160 meter 1/2 wave dipole running from the top of the tower to a tree in front of the house. When things started getting bad I would just leave the shack and hope for the best.