Much what is said is true, but I will add a few points. Forty some years ago I worked for a 2 way radio co. We had the Yellow Cab contract. I was at Yellow Cab on Hays street in north Houston. I was replacing 2 radios in the radio shack at the base of the 450ft tower that had been removed and taken to the shop for repair. As I got setup to replace the radios in the rack, there were 4 radios & 4 standby radios in the rack. They used 4 VHF channels at that time. There was a thunderstorm approaching outside. The radio shack was just a small 8x 12 building a the tower base. The radios were DC remote controlled from the dispatch office located 100 ft away. I waited for the storm to pass before installing the repaired radios, as I did not want the touch the rack a long as the storm was near. As I sat on the floor of the shack looking out the door, it was raining real hard. I then saw lightning strike the power lines behind the mechanic shop about 300ft away. It blew a AC receptacle on the wall behind me off the wall. Damaged 2 of the 4 radio power supplies, 1 DC remote. I had disconnected all the standby equipment before the storm to facilitate the installation of the replacement radios. To make a long story short (LOL) The lightning hit the power line 300ft away from a 450ft tower. No lightning came down the tower. So just being high in the air, does not necessarily make it a lightning rod.
What is important is bonding everything together. If all equipment in your shack is at the same potential, the lightning current will not have anywhere to flow. I can charge the case of your K3 with 10,000v but if there is no current flow no damage will occur. If lightning hits the power line and the ground rod at your shack is a better path than the AC ground at your meter the current will travel thru your rig to get to the rod. If you bond the shack/antenna ground with the AC ground with a #6 wire. Since both are at the same potential, there will be no current flow & no damage. ( this bonding is required by the NEC) See Mike Holt on you tube to understand this. Robert KD5YVQ From: BVARC <[email protected]> On Behalf Of Eddie Runner via BVARC Sent: Wednesday, April 08, 2020 9:53 AM To: Mark Brantana via BVARC <[email protected]> Cc: Eddie Runner <[email protected]> Subject: Re: [BVARC] Antenna Mounting Options Mark, it is true, lightning does what it wants to do. I have had outside antennas of all types including towers , long wires, dipoles, cb antennas, shortwave, Ham of all kinds, over the past 50 years, I have had houses with ground rods and houses without ground rods and even when I had ground rods some antennas would sometimes not be grounded... (one house I had 19 antennas up at one time).. I have a rule, if there is a threat of lightning, I AM NOT GONNA TOUCH THAT COAX.. So that means I NEVER disconnect my coax when a storm comes.. NEVER...NEVER... As far as I can remember I have never had lightning damage on any radio gear.. Back in the 80s there was some speculation that lightning may have come in through the phone line and destroyed 2 modems ( I used to run BBS's).. I have seen a few times where lightning hit TOWERS or POWER PANELS on homes, some were hams and some were just people with no antennas... I have seen gear supposedly hit by lightning.. Maybe some was, maybe some just blew the finals cause the guy forgot to hook up the coax he unhooked the last time he heard thunder.. ha ha But even all the times we know about, it is still fairly unlikely.. and if the lightnng has your name on it.. ??? Good luck.. it is all VOODDOO..ha ha Eddie (NU5K) On Wednesday, April 8, 2020, 06:16:29 AM CDT, Mark Brantana via BVARC <[email protected] <mailto:[email protected]> > wrote: Since folks are hunkered down anyways, here is a problem. I am improving my emergency radio capability by adding a 2-m radio to my home office. Who knows where this thing is going, and I think this is a good time to prepare. I would like your thoughts or experience with the following. I am looking to mount a 2-m antenna on my roof. Currently I have a TV antenna attached with a j-pole just below the chimney output. I have a single-story house. My plan has been to extend the j-pole about 4 ft higher to get better TV reception, and mount the antenna just above it. I do have to watch out for offending the HOA. My property has power lines running parallel with the back of the house, and these power lines are about 35 feet high and 35 feet laterally away from the chimney. I am concerned about a couple of things: 1. Some day I may want to start a fire in the fireplace, and I do not want the heat to get to the antennas. This is why I have the TV antenna mounted below the top of the chimney. 2. I would like to avoid arching or lightning strikes, though I think it is quite common for most of us to have power lines around to contend with. Two thoughts here: a. Of course, I will ground it all. b. I wonder if the power lines might protect the lower antennas since lightning may hit them first. I mention this since the first thought was that the power lines might add to the lightning risk, not detract. c. That said, lightning does what it wants, and even a nearby lightning strike, as opposed to a direct strike, will do significant damage. On that last point, I will share a short story. When in Louisiana many years ago, we got into a discussion about how lightning had destroyed a lot of equipment in a member’s shack. This included, as I recall, about 3-5 computers, and about as many radios. This was all sitting on a metal table. Due to the lightning storm, the Ham had disconnected all of the antennas. Lightning hit his tower and made the 2” jump to the table. The rest was history. But, that was not the story I wanted to tell. That was the discussion we were having. Another Ham broke in and told us that he had a tower at one end of his house which was operational, and he had just that day mounted a short marine antenna at the other end of the house on his chimney. It was a dark and stormy night the previous evening, and the lightning passed the tower to hit the yet unconnected marine antenna. So, lightning does not follow the rules. OK, so I diverged. I really would like to know what experience and advice you can offer me on my project. The power lines make me nervous, and I really wish my best mounting option were not in the heat zone of the chimney. Mark N5PRD ________________________________________________ Brazos Valley Amateur Radio Club BVARC mailing list [email protected] <mailto:[email protected]> http://mail.bvarc.org/mailman/listinfo/bvarc_bvarc.org
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