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Author Topic: Seeking lightening arrester advice  (Read 8505 times)
NK7Z
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« Reply #15 on: September 17, 2014, 10:14:31 PM »

I also run high power up to legal limit.  The high VSWR results in high voltages in the feedline, causing my Polyphaser arrestors to shunt the high voltage to ground.  The causes my SS amp. to fault. 
73,
Jonathan W6GX
You are going about this backwards...  Instead of patching the problem with bigger stuff, fix the problem...  Find out why you have high SWR, or run less power.  I am not trying to state the obvious, but you have an issue with your antenna, and it is causing other things to fail...  Fix the antenna and things will work better all around...
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Thanks,
Dave
For reviews and setups see: http://www.nk7z.net
W6GX
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« Reply #16 on: September 17, 2014, 10:56:37 PM »

You are going about this backwards...  Instead of patching the problem with bigger stuff, fix the problem...  Find out why you have high SWR, or run less power.  I am not trying to state the obvious, but you have an issue with your antenna, and it is causing other things to fail...  Fix the antenna and things will work better all around...

Thank you for your good intentions.  I'd love to have another antenna.  However adding another antenna will cause my tower to be overloaded, with the possibility of catastrophic failure in windy conditions.  Getting a second tower is not an option.  Replacing my yagis with another antenna that covers the WARC band is an alternative that I might explore but it's not on the table at the moment.

I'm now considering replacing the stock GDT with another unit that is rated in the range of 1,500v.

73,
Jonathan W6GX
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K1ZJH
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« Reply #17 on: September 18, 2014, 10:14:20 AM »

I have the best lightning arrester around, it's called unplug the coax. Grin

I agree. I float antennas in storm and switch rigs into a dummy load. In past 30 years I have had 4  very close hits. Two cause minor and two caused major damage and none struck antennas or damaged ham gear but I did loose computers, routers, TV's, microwaves etc.

Yeah, like switching to a dummy load is going to do anything to save you from common mode lightning current/voltage.  What if all of the damaging potential is carried on the SHIELD, as it is 99 percent of the time? 
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N1BNC
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« Reply #18 on: September 18, 2014, 12:25:25 PM »

The issue is 12/17/30m. One could arrange 3 dipoles 120° apart as slopers on the side of the tower and then switch between them for directivity.

Here is a home made variety: http://boringhamradiopart.blogspot.com/2010/02/warc-trap-dipole.html
« Last Edit: September 18, 2014, 12:47:29 PM by N1BNC » Logged
AA4PB
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« Reply #19 on: September 18, 2014, 01:33:12 PM »

Yeah, like switching to a dummy load is going to do anything to save you from common mode lightning current/voltage.  What if all of the damaging potential is carried on the SHIELD, as it is 99 percent of the time? 

You can ground the shield without using a surge protector. He said his switch grounds all unused antennas so when in the off position it will short the center conductors to the shields just like a surge protector will when it fires. The surge protector doesn't do anything about common mode currents unless it is properly grounded. The switch, when no antennas are selected, should provide as much protection as a surge protector provided you have the shields properly grounded before they enter the house.

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K1DA
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« Reply #20 on: September 23, 2014, 08:42:08 AM »

I'm re-arranging my shack right now and building a patch panel. I'm thinking about adding a row of SO and BNC connections on the bottom row and grounding those to a seperate rod so that I can take the radios out of the circuit and shunt the feedlines to the ground plugs.

Good idea or not?
  Google W8JI,  he has a lot of good info on the proper constructon of patchpanels, including some nice photos.
« Last Edit: September 23, 2014, 08:44:30 AM by K1DA » Logged
K1DA
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Posts: 525




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« Reply #21 on: September 23, 2014, 08:48:20 AM »

You hold an Extra class license. Shouldn't you be able to figure this out by yourself?
 Now THAT'S constructive and in the TRUE amateur spirit.
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KG4RUL
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« Reply #22 on: September 23, 2014, 10:55:36 AM »

To alleviate a "lightening" problem, might I suggest more weight on the antenna?

HI HI HI
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W4KVW
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Posts: 508




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« Reply #23 on: September 28, 2014, 01:09:19 PM »

http://www.smithspower.com/brands/polyphaser Other than unplugging these are the CREAM of the crop & why major radio markets use them on their sites.NOTHING is 100% fool proof unless you unplug the coaxes & power cords period.

Clayton
W4KVW
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AA4HA
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« Reply #24 on: October 06, 2014, 09:58:19 AM »

There are some gas-tube-arrestors on the market that have a replaceable element. Gas tubes come in all sorts of firing voltages. Even the leaded gas tubes are usually the same physical size as the pills. You can snip the leads off of those and insert them in the holder.

I am not endorsing any particular brand or model but take a look at some of the choices;

https://www.tessco.com/products/displayProducts.do?groupId=90143&subgroupId=90567

They are all essentially the same type of design. These are "DC pass" protectors. It is a straight through center conductor with a gas tube to ground.

When you see a "DC block" protector they add a capacitor in series.

The advice you have been given, and what you have seen, that with a high VSWR you get high voltage locations on your feedline and those high voltage spots move around depending upon the frequency. you could add a short chunk of coax and it will move the high voltage spot somewhere else but it is really not fixing your problem, and that is why you have high VSWR. You correctly surmised that the protectors have a rating where they assume a certain VSWR and they give their power handling rating based upon that in addition to what the firing voltage is on the gas tube element.

The aluminum cube type Polyphaser protectors have gas tubes in them too but you need to dissect them to see it. For your application I suggest the cylindrical or elliptical shaped protectors that have the nut or screw that holds the element in place.

Note that with a high VSWR at the power levels you are dealing with you may not find a tube that has a high enough voltage rating. Also the higher the rating the more Joules of energy is going to be let-through on a transient event.
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Ms. Tisha Hayes, AA4HA
Lookout Mountain, Alabama
N8CMQ
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Posts: 386




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« Reply #25 on: October 26, 2014, 08:29:51 AM »

I am with the others that say unplug coax and power plugs.

I have lost telephones and televisions due to indirect lightning
strikes. One time the arc happened in the wall mounted phone
jack I was sitting next to, scared the heck out of me...

I always disconnect coaxes and move them to the ground bus,
and I also unplug the line cords when not in use.

Only once have I had a direct hit, and it split a walnut tree so
badly, it had to be cut down. I have never lost my radios or
computers, as those are disconnected at all times they are not
in use.

As far as that little #6 cable goes from your cable entrance to
your service entrance, keep it outside if at all possible.
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NN4RH
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Posts: 330




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« Reply #26 on: October 27, 2014, 02:54:32 AM »


Solve the antenna problem first (high VSWR).   
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KM4BYJ
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« Reply #27 on: October 28, 2014, 04:02:52 PM »

You hold an Extra class license. Shouldn't you be able to figure this out by yourself?

I may be new to ham radio but in my engineering career I've observed that the very best, smartest engineers never stop asking for advice. Also, the very best understand they don't know everything and they've forgotten a lot. They're efficient, so when they come up short, they ask people who may already know the answers. If the answers don't make sense, they go deeper into the issue on their own.

If you're an experienced ham with an Extra license, surely you should have figured this out yourself by now.
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73

Al
KM4BYJ
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