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 Post subject: Another Long Wire Antenna Question
PostPosted: Dec Sun 31, 2017 8:46 am 
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Location: Hamilton, Ontario
I want to hook up a long wire antenna.

Tell me if I have this correct.
I am using 14ga single strand coated wire.
The distance between the isolated ceramic spools will be around 70 feet.
My lead in wire will be the same 14 ga wire.
This is my lightning arrester:
http://www.tscstores.com/Zareba-Lightni ... 17357.aspx

Does running a loop as shown help at all or is one wire from point to point better?
Do I have the ground setup correct?

diagram below:
Image

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 Post subject: Re: Another Long Wire Antenna Question
PostPosted: Dec Sun 31, 2017 9:12 am 
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Joined: Sep Thu 23, 2010 6:37 am
Posts: 9490
Location: Powell River BC Canada
Find out the frequency of lightning strikes in your area.

https://weather.gc.ca/lightning/index_e.html

Is the lightning arrestor from the from the fencing supply company
approved for home aerial use?

A local electrical contractor could answer this.

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 Post subject: Re: Another Long Wire Antenna Question
PostPosted: Dec Sun 31, 2017 1:50 pm 
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Joined: Jan Thu 01, 1970 1:00 am
Posts: 7773
Location: Cleona, PA
A single long wire will work as well as what you show. You have your lightning arrestor wired incorrectly. The arrestor is nothing but an internal spark gap, like a spark plug. One terminal connects to the antenna, the other end to ground, to pass antenna surges hopefully to ground via a spark. The same arrestor terminal connected to the antenna, connects to the lead-in wire to the radio (detail below.) Best to disconnect that wire when not using the radio to avoid the danger of nearby lightning when you're not around to disconnect it.


Attachments:
fig006b.png
fig006b.png [ 32.35 KiB | Viewed 680 times ]

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 Post subject: Re: Another Long Wire Antenna Question
PostPosted: Dec Sun 31, 2017 1:59 pm 
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Joined: Jan Thu 01, 1970 1:00 am
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Location: New Virginia, IA
With regards to lightning arrestors, they don't work.

Disconnect the external antenna when not in use or during the threat of lightning.


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 Post subject: Re: Another Long Wire Antenna Question
PostPosted: Dec Sun 31, 2017 2:30 pm 
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Location: Cleona, PA
Arrestors may take care of strong static build-ups, but nothing will protect from a near-by or direct strike. A million volts is going to just laugh at whatever you throw at it. A couple of years ago lightning struck a huge oak tree in my front yard, since cut down. The antenna is out back. It took out the antenna coil in one radio, the DSL modem, and the WiFi router. It sounded like a huge sledge hammer hit the house. Disconnecting is the safest way. I have my antenna connected to an old-timey SPDT porcelain switch on the shop wall where the antenna lead comes inside. Switch up, antenna goes to the radio. Switch down, radio disconnected from antenna, and antenna directly grounded through the bottom stationary connection on the switch. The arrestor is outside grounded through being mounted on the metal mast that supports one end of the long wire.

Interestingly, many have used spark plugs for lightning arrestors, pictures on the web. I could see closing that gap down to paper thin.

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 Post subject: Re: Another Long Wire Antenna Question
PostPosted: Dec Sun 31, 2017 3:19 pm 
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Location: Fredericton, Canada
This is what I built precisely to the instructions. Very simple but effective in reducing noise levels. Using water pipes as a ground can often introduce more noise . http://web.archive.org/web/200310120551 ... tenna.html

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 Post subject: Re: Another Long Wire Antenna Question
PostPosted: Dec Sun 31, 2017 3:19 pm 
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I don't understand the loop of wire deal. Seems like it would accomplish little but make the antenna heavier and use twice as much wire for no advantage. I like the idea of just disconnect the antenna when weather threatens. If you think you will have some issue with static buildup, a large value resistor could bleed off static to ground from the ant. but not do anything for real protection. You could also ground the antenna directly with a knife switch like was suggested, but then my unscientific mind wonders if a grounded antenna makes for a more attractive target, than just being a floating disconnected piece of wire? I assume one can reduce one's chances of lightning damage but not completely, I think sometimes it does as it pleases. Alot of protection is for bypassing more likely induced surges, not a direct hit. You did not say how high the ant. will be. Higher is better. Probably more so as frequency rises and the signals come from farther away at lower angles.


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 Post subject: Re: Another Long Wire Antenna Question
PostPosted: Dec Sun 31, 2017 6:11 pm 
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Location: Hamilton, Ontario
The height of the antenna will be around 30 feet. I am not looking to transmit or do any serious SW receiving. I am really interested in getting much better AM reception and slightly better SW reception out of interest.

I have read about spark plugs and neon bulbs and such for arrestors and even that they don't work at all for direct or close by hits. Just for my own piece of mind I would like to set something up anyhow though for the relatively little that it costs.

I also have 60 foot plus trees all around my home. This is NOT hooked up to any trees though.

1) Would this interior little knife switch work or should I have a double terminal switch (one for antenna and one for ground)
https://www.lowes.ca/lamp-parts-accesso ... 66443.html
2) Do I have the arrestor and ground set up properly now?
3) I understand that a direct or nearby strike would blow out a resistor but can I/Should I put say a 10W power resistor between the terminals of the arrestor to bleed off static? If so how many ohms is appropriate?

Here is my revised diagram:

Image

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 Post subject: Re: Another Long Wire Antenna Question
PostPosted: Dec Sun 31, 2017 7:05 pm 
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Location: West Point, PA
That diagram looks better. That's a nice knife switch, too. (It better be for that price)
Attachment:
Antenna2.jpg
Antenna2.jpg [ 49.08 KiB | Viewed 601 times ]


You can also connect the knife switch to just short the antenna out to ground and this will do away with any static charge that builds up on the wire. Wazz had a good thought. Does grounding the antenna make it a target for lightning? I've always grounded mine with the knife switch, but in my case a tree or chimney would be struck before it found my rather low hanging long wire.
Attachment:
Antenna3.jpg
Antenna3.jpg [ 24.73 KiB | Viewed 598 times ]

If you use a double throw switch you can both disconnect the radio from the antenna and ground the antenna at the same time.


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 Post subject: Re: Another Long Wire Antenna Question
PostPosted: Dec Sun 31, 2017 10:01 pm 
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jrs wrote:
I am not looking to transmit or do any serious SW receiving. I am really interested in getting much better AM reception and slightly better SW reception out of interest.

I have read about spark plugs and neon bulbs and such for arrestors and even that they don't work at all for direct or close by hits.

I have an approximately 240' random length long wire antenna on my back acre. I also built a 23" diameter tunable loop.

They both work about equally on the BCB, so a loop could be an alternative for you.

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 Post subject: Re: Another Long Wire Antenna Question
PostPosted: Dec Sun 31, 2017 11:00 pm 
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Lightning travels in a straight line (unless it wants to do otherwise, but that's its idea).

For a lightning arrestor to have any chance of working, the route from the end of the antenna through the lightning arrestor, then through the ground rod to ground MUST be a straight line.

- Leigh

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 Post subject: Re: Another Long Wire Antenna Question
PostPosted: Dec Sun 31, 2017 11:32 pm 
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Location: Hamilton, Ontario
What about the question of putting a resistor in between the leads of the arrestor to discharge static and if so what wattage and ohms would it require

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 Post subject: Re: Another Long Wire Antenna Question
PostPosted: Jan Mon 01, 2018 12:30 am 
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I have an old Belden lightning arrestor for a doublet antenna. Inside are two 100K 1/2W resistors. There is no spark gap at all. I guess the idea is that a sudden surge would just arc through the resistor. Surprisingly, the rather cheap looking vintage resistors are still within their marked 20% tolerance.

The antenna lead in should be at the house end of the antenna, not the far end as shown in your drawing. Also, the receiver should be connected at the lightning arrestor, not some place above it. The wire from the lightning arrestor to ground should be short and straight.

I question your choice of lightning arrestor. One made for electric fences has to withstand several thousand volts without arcing. A receiving arrestor would protect at a lower voltage.

As for an antenna attracting lightning, that is an open question. One theory is that a solidly grounded antenna discharges the static in the air around it preventing lightning. It hasn't been proven either way. In any event, I have a tower about 60' high in my back yard. It has been there for about 25 years and hasn't been hit yet.

Be sure to put a drip loop in the wires going into the house to prevent rain from running in.

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 Post subject: Re: Another Long Wire Antenna Question
PostPosted: Jan Mon 01, 2018 12:34 am 
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Use all the lightning protection you like - if you get a direct strike, everything's toasted. You may be able to get rid of static build-up with a resistor to ground - say 47k or something like that, or even have a high-to-low impedance transformer right up at the antenna with a ground wire straight onto the ground spike and coax down to another low-to-high transformer at the bottom and then to your radio.

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 Post subject: Re: Another Long Wire Antenna Question
PostPosted: Jan Mon 01, 2018 5:54 pm 
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Location: Thornhill, Ontario
jrs wrote:
... 3) I understand that a direct or nearby strike would blow out a resistor, but can I/Should I put say a 10W power resistor between the terminals of the arrestor to bleed off static? If so how many ohms is appropriate?
Yes, it would! I'd use a 47K to 100K resistor to ground to bleed off static, but it need not be 10 watts! In static drain mode, power would be "zero".
BTW, I presume you're using solid wire because you have it to hand. It will not last long if flexed, e.g. by the wind or a moved lead-in. Multi-strand flexible wire is usually easier to install and lasts longer. That said, I'd use up the "free" stuff first!
Cheers,
Roger

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 Post subject: Re: Another Long Wire Antenna Question
PostPosted: Jan Mon 01, 2018 7:55 pm 
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Joined: Jan Thu 01, 1970 1:00 am
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Location: North of Mpls, Minnesota
Your ground rod must be tied into your house wiring ground rod to protect from ground strikes (And it is the electrical code in the US) If you do not have the antenna and ground system to code your house insurance may not pay if you are struck.

Dave


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 Post subject: Re: Another Long Wire Antenna Question
PostPosted: Jan Mon 01, 2018 8:34 pm 
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Joined: Jan Thu 01, 1970 1:00 am
Posts: 3184
Location: California
I have several wire antennas connected to radios, and they all have a Polyphaser in series. the Polyphaser not only bleeds static off the antenna wire to ground, but it also isolates the radio from the antenna wire.

Using an ohm meter, there is no DC continuity through the Polyphaser. There is a DC path to ground on the antenna side of the unit.

I don't have to worry about lightning (as much) now. In fact, one of my towers has been hit by lightning, and the radios just kept playing.

A web search for Polyphaser will turn up what you need.


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 Post subject: Re: Another Long Wire Antenna Question
PostPosted: Jan Mon 01, 2018 8:38 pm 
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Paul wrote:
Using an ohm meter, there is no DC continuity through the Polyphaser.

What does you ohmmeter say about the 2000-foot air gap that the bolt just jumped ?

Absolutely and totally useless...
And dangerous because it brings the antenna line into the house before any lightning arrestor.

- Leigh

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 Post subject: Re: Another Long Wire Antenna Question
PostPosted: Jan Tue 02, 2018 5:10 am 
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engineer wrote:
jrs wrote:
... 3) I understand that a direct or nearby strike would blow out a resistor, but can I/Should I put say a 10W power resistor between the terminals of the arrestor to bleed off static? If so how many ohms is appropriate?
Yes, it would! I'd use a 47K to 100K resistor to ground to bleed off static, but it need not be 10 watts! In static drain mode, power would be "zero".
BTW, I presume you're using solid wire because you have it to hand. It will not last long if flexed, e.g. by the wind or a moved lead-in. Multi-strand flexible wire is usually easier to install and lasts longer. That said, I'd use up the "free" stuff first!
Cheers,
Roger

i had a metal film bleeder that was connected to one of my massive beverages turn to clear see-thru glass after a nearby strike.

it was a five watt resistor.

nothing will protect you from a direct strike.

ask me how I know about that too.

:twisted:

steve

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 Post subject: Re: Another Long Wire Antenna Question
PostPosted: Jan Tue 02, 2018 4:09 pm 
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Location: S. Dartmouth MA 02748-1225 USA
Poyphaser?

Hmm My local radio club has been through at least two sets of them. Not only were the 'phazers destroyed, many 100's of dollars of gear fused despite the devices.

Not the story but here is the local radio club SEMARA:

http://semara.org/

The towers are seen in the background.

The back story: The site was once a dump/swamp and there is a defined layer of rusted cans that covers about an acre. The club negotiated in 2000 and is leasing to a cell tower provider the space for the tower. The lease is cell provider dependent and is the source of revenue to operate the club... Thus, membership is free.

The club has exclusive right to the three top ends of the cell tower for the repeaters. Both the cell tower and the clubs HF tower all communicate via large coax as well as cat-5 in buried steel conduits to/from the buildings. Both tower installations were professionally done so there is a more than ample footing and grounding.

Yep the towers get hit...

Would there be more damage if the Polyphasers were not installed?

It is believed that the extensive damage is not from the hit itself but from a pulse that extends out and induces high voltage in metal objects, both above and below ground.

There are archives that go back many years stored on the web site:

http://semara.org/zerobeat/

FWIR there is info about lightning damage.

Many editions of Zerobeat have been lost to time, no club member can find one to scan.

Chas


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