Author Topic: When to disconnect your antenna  (Read 5311 times)

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dangerdan

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When to disconnect your antenna
« on: July 20, 2015, 11:44:45 AM »
During the summer months , weather can get volatile .
Lightning is a big concern when it comes to ham radio .

 I use  http://www.lightningmaps.org
This map is as real time as it gets , I check the weather before connecting to my antenna .

Hope this helps someone .


73

DD
« Last Edit: July 20, 2015, 11:46:45 AM by dangerdan »

AD

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Re: When to disconnect your antenna
« Reply #1 on: July 20, 2015, 04:03:09 PM »
What antennas do you have?  I have 2 end fed wires in a pine tree in the front yard.  The feed lines come through the block fense into a pass through panel. 

This is the pass through panels I use. http://www.kf7p.com/KF7P/EntrancePanels.html

Here are some photos of them
http://www.kf7p.com/KF7P/Gallery.html#3

On the inner panel copper plate are lighting arresters.  This copper backing plate is the bonded to a flat copper strap  that is connected to a grounding rod.

The other side of the lighting arrestor attached the 75 ft of coax coming into the second floor shack.

Using this system I don't know if I am gambling but I just switch the antenna switch for ground in the shack.
« Last Edit: July 20, 2015, 04:07:43 PM by AD »
The only dumb question is the one that did not get asked!!

Tevin

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Re: When to disconnect your antenna
« Reply #2 on: July 20, 2015, 09:46:34 PM »
During the summer months , weather can get volatile .
Lightning is a big concern when it comes to ham radio .

 I use  http://www.lightningmaps.org
This map is as real time as it gets , I check the weather before connecting to my antenna .

Very interesting website and project. I looked over the engineering description .pdf and it's obvious someone put a great deal of time and effort and probably money into this. It is very deep and technical. When they say their system is not "plug-and-play," they are not joking.

I used to work at a commercial FM radio station and we had a very expensive and complex system of sensors on and around our broadcast tower. They would calculate the electrical charge in the air and energize the tower, guy wires, buildings, everything, to have the same charge, eliminating any voltage potential between the tower and the atmosphere. No potential literally made the tower electrically invisible and it was physically impossible for it to be hit by lightning.

As we explained it to the boss when we were trying to talk him into spending the money, "You can't fall if you're already on the ground."

We went from 6-8 direct lightning strikes per year, plus dozens of near misses that caused minor damage, to zero. Nothing. The system worked brilliantly, and quickly paid for itself in expenses saved on repairs.

As a side effect, a nearby church which had never once been hit by lightning was nailed two times less than a month after our system went live. Apparently, we had been protecting them all those years. As soon as lightning became "blind" to our tower, the juice went for the next likely target, which just happened to be the church.

When the church people found out why they suddenly started getting hit by lightning, they had a major hissy fit and complained to station management. The boss was understanding, but what was he supposed to do? Turn the system off and start taking lightning hits for them? I'm not sure how or if the matter was resolved because I left soon after. The radio tower and the church are still there.


« Last Edit: July 21, 2015, 08:17:29 AM by Tevin »

spacecase0

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Re: When to disconnect your antenna
« Reply #3 on: July 21, 2015, 02:33:20 AM »
my antennas are only connected when I am using the radio,
I have run tests, to much gets in on the shield of the coax to just short things with an antenna switch
and I hope that things not connected that often works out well enough (backup radios are stored in case one gets fried)

BTPost

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Re: When to disconnect your antenna
« Reply #4 on: July 21, 2015, 02:25:38 PM »
One of the very NICE things about living in the Bush of Alaska, where I do, IS that we get a Thunder & Lightning Storm, about once a DECADE.... When we first moved here, we had a storm one night, and one of the Old Native Ladies, said that was the SECOND time in her life she had seen Lightning.... The time before, was 60 years before, when she was a child. Most of the few storms we see, are Air to Air Discharges and only very Rarely do they ever go Air to Ground... around here.... We also do NOT have Tornados, and only once in 40 years did we have a Hurricane.... We do get 150 Kt winds every winter though, but they just Blow out in a Day or so.... Apparently, Thor's Hammer doesn't strike much in my neighborhood.... so My Antennas stay connected 99% of the time.....
Bruce in alaska AL7AQ

tazdevil

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Re: When to disconnect your antenna
« Reply #5 on: July 21, 2015, 10:28:45 PM »
Here in Arkansas during the summer, we have pop up thunderstorms that can strike at any time, so I have all the grounds, protectors and such, but I still unplug all coax, I have seen first hand what a direct hit can do, and no amount of protection will protect your gear from it.

dangerdan

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Re: When to disconnect your antenna
« Reply #6 on: July 24, 2015, 08:08:14 AM »
AD asked" what antennas do I have? "
For 2 meter ,I homebrewed a slim-jim inside of grey electrical conduit ,tuned with aluminum foil tape on the outside @ 16 feet elevation .

A homebrew 5 band fan dipole @ 32 feet cut for 80,60,40,20,10 meters ,it tunes ,<3:1 15,12,6 meters .

A home brew 17 meter delta loop ,not connected because it made good friends with the fan dipole so fan tunes 17 meter now@,<3:1  .

I just recently built a hex beam from plans  http://www.hex-beam.com 

G3TXQ Broad band Hex beam by K4KIO .

I bought the hub from DX engineering (great company ) and the fiberglass tubing .

I initially intended to go cheap with materials ,but winds on the hill would have made it a short term antenna .
   Installed on a light aluminum tower @ 25 feet , cut for 20, 17,15,12,10, and 6 meters ,<2:1 very good results so far ,still some issues to resolve with the rotor .
I wish that I had had the Hex beam for the ARRL centennial .

All the antennas were tested with mini VNA .

73
DD
« Last Edit: July 24, 2015, 08:11:28 AM by dangerdan »

AD

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Re: When to disconnect your antenna
« Reply #7 on: July 24, 2015, 08:53:09 AM »
Thanks DD.  I need to figure out a new antenna set up for my HOA.  I have the 2 end fed wires in a tree but the performance is less than OK.  I don't have a lot of options and for the foreseeable future little $$$ to help solve the problem. 
The only dumb question is the one that did not get asked!!

Flight-ER-Doc

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Re: When to disconnect your antenna
« Reply #8 on: July 25, 2015, 09:33:06 AM »
If you are worried about a lightning strike or EMP you should disconnect and ground your antenna leads OUTSIDE of your shack/house.

Bringing the current inside is a bad idea, not just for your radios but all the wiring in your house, and potentially the biological lifeforms there as well.

I have a pass-through panel with polyphasers for routine use, and still disconnect outside when I'm away or have concerns about a strike.

Of course ymmv

spacecase0

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Re: When to disconnect your antenna
« Reply #9 on: July 25, 2015, 09:30:32 PM »
I disconnect power wires, antennas, ground connections, and the microphone from the radio if I can
the power pole connectors seem to not wear out doing that, but no so sure about the microphone connector
also set up an RF choke on my solar power wires (yes on the + and -), but they get disconnected as well after the batteries finish charging and are not connected unless I am using a radio or it is morning and time to charge batteries again
also helps that my ham shack is a faraday cage
I am likely a bit obsessive with a few things, and that is one of them.

also I have seen pulses not damage the radio hardware, but did mess with the software,
have a hard copy of your radio processor reset instructions handy along with all the frequencies you have programmed into it