Author Topic: Relocate Boltek antenna on top of push up pole  (Read 8350 times)

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Offline capeweather

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Relocate Boltek antenna on top of push up pole
« on: March 04, 2012, 09:28:46 AM »
My anemometer sits on top of push up pole roughly 33' in the air. The pole is made out of metal and would like to place my Boltek antenna on top of the pole. The question is, would it be ok to place it on top enclosed in the PVC dome that most folks are using? It is currently in the attic and would like to get it outside for range and accuracy. New duct work was installed in my attic and it seems that the foil on the flex is causing dead spots. Also, I will need to add more cable but would like to avoid paying the high price of the cable from Boltek. I can get a spool of Cat5 or Cat6 shielded cable for relatively cheap and will need approximately 200 feet. Can the cable be coupled together or does it need to be one continuous piece? Any suggestions or help appreciated.
« Last Edit: March 04, 2012, 09:36:30 AM by capeweather »

Chris
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Offline SoMDWx

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Re: Relocate Boltek antenna on top of push up pole
« Reply #1 on: March 04, 2012, 09:46:55 AM »
Cape,
  I would go with one contiguous run if possible. I don't see an issue putting it up on your anemometer pole...Only issue I see is possible reflection from the pole itself if it is mounted right on it...Someone else could possibly shed some more info...

Jim

Offline neondesert

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Re: Relocate Boltek antenna on top of push up pole
« Reply #2 on: March 04, 2012, 10:19:29 AM »
Chris,

My Boltek antenna has been mounted on top of a metal mast since I've installed it (7 years ago) and it works just fine. If there are any
reflection issues they haven't been noticeable.

As far as the cable is concerned coupling should not be an issue either. 
I'm sure others that have already lengthened their cable runs will chime in with their experience. 
Larry
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Offline capeweather

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Re: Relocate Boltek antenna on top of push up pole
« Reply #3 on: March 04, 2012, 06:31:04 PM »
Thanks guys, appreciate the response. Larry, if you have any photos could you post them? I have ideas in my head on how I want to mount it but a picture may be helpful. Also, it probably doesn't make a difference on the cable, but can CAT6 be used? I have two 100' CAT6 shielded cables in the garage that I use for webcams. Thanks again.

Chris
Cape Coral, Florida
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Offline neondesert

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Re: Relocate Boltek antenna on top of push up pole
« Reply #4 on: March 04, 2012, 07:54:06 PM »
Thanks guys, appreciate the response. Larry, if you have any photos could you post them? I have ideas in my head on how I want to mount it but a picture may be helpful. Also, it probably doesn't make a difference on the cable, but can CAT6 be used? I have two 100' CAT6 shielded cables in the garage that I use for webcams. Thanks again.

Sure Chris.  The housing is getting a little "sun weathered" and will be replaced this spring.

Here ya go:


As far as cabling is concerned CAT6 should be fine, at least according to a quick search here on the forum.  ;)
Larry
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Offline capeweather

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Re: Relocate Boltek antenna on top of push up pole
« Reply #5 on: March 04, 2012, 09:16:23 PM »
Thanks Larry, much appreciated with the photo! That was one of the ideas I was thinking and will probably take the route you did. Do you get a lot of sway in heavy winds? I would imagine it stays pretty stable with the guy wires. Mine are relatively tight and the sway is very minimal even with gusty winds.

Chris
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Offline neondesert

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Re: Relocate Boltek antenna on top of push up pole
« Reply #6 on: March 04, 2012, 09:36:12 PM »
Before the guy wires there was some movement but not a lot.  Since I put the guy wires on I
haven't noticed any appreciable movement even in 40+ mph winds.
Larry
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Offline C5250

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Re: Relocate Boltek antenna on top of push up pole
« Reply #7 on: March 05, 2012, 11:24:00 PM »
What sort of lightning protection does this have?

I do have to say, I find it kinda amusing that someone would stick a lightning detector up in the air like a lightning rod without any apparent thought about lightning protection.

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Offline kray1000

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Re: Relocate Boltek antenna on top of push up pole
« Reply #8 on: March 05, 2012, 11:40:22 PM »
What sort of lightning protection does this have?

I do have to say, I find it kinda amusing that someone would stick a lightning detector up in the air like a lightning rod without any apparent thought about lightning protection.

My thoughts were similar.  In a state with so many lightning storms, and with such a long run of cable up a metal pole, I'd be concerned about lightning protection as well.

Offline capeweather

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Re: Relocate Boltek antenna on top of push up pole
« Reply #9 on: March 06, 2012, 07:09:35 AM »
I have an eight foot grounding rod that has been put into the ground within 1 foot of placement. The pole has been up for 5 years and hasn't taken a direct strike.

What sort of lightning protection does this have?

I do have to say, I find it kinda amusing that someone would stick a lightning detector up in the air like a lightning rod without any apparent thought about lightning protection.



Chris
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Offline C5250

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Re: Relocate Boltek antenna on top of push up pole
« Reply #10 on: March 06, 2012, 10:23:59 PM »
I have an eight foot grounding rod that has been put into the ground within 1 foot of placement. The pole has been up for 5 years and hasn't taken a direct strike.

I assume that means your mast is properly grounded.

First, if the mast does take a direct strike, your ground wire will be vaporized and it is unlikely the mast would not also suffer damage. The whole point of proper grounding is to reduce the risk of a direct strike.

My concern is locating something electrically connected to inside the building outside of the cone of protection that a properly grounded mast would offer. You won't need a direct strike to fry the antenna, the card in the computer and more.
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Offline dalecoy

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Re: Relocate Boltek antenna on top of push up pole
« Reply #11 on: March 06, 2012, 10:55:08 PM »

My concern is locating something electrically connected to inside the building outside of the cone of protection that a properly grounded mast would offer. You won't need a direct strike to fry the antenna, the card in the computer and more.


That's an interesting thought.  Do you have one of these Bolteks?  Curiously, it's really difficult to figure out how to have a lightning detector that is protected against (nearby) lightning strikes, but where the protection does not interfere with the functioning.

And lots of folks mount their Boltek antenna in the attic.  Any nearby strike is equally likely to fry all that stuff.


Offline C5250

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Re: Relocate Boltek antenna on top of push up pole
« Reply #12 on: March 06, 2012, 11:40:25 PM »
That's an interesting thought.  Do you have one of these Bolteks?  Curiously, it's really difficult to figure out how to have a lightning detector that is protected against (nearby) lightning strikes, but where the protection does not interfere with the functioning.

And lots of folks mount their Boltek antenna in the attic.  Any nearby strike is equally likely to fry all that stuff.

Yes, and mine is in the attic as well, well within the cone of protection afforded by the (properly grounded) mast my anemometer is mounted on. I would entertain thoughts of how to safely mount it higher. For anything in the past, it was usually a simple matter of something like a spark gap arrestor on the lead-in. I've no idea how to obtain the same protection with an active antenna like the Boltek uses...
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Offline dalecoy

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Re: Relocate Boltek antenna on top of push up pole
« Reply #13 on: March 07, 2012, 09:56:20 AM »
Yes, and mine is in the attic as well, well within the cone of protection afforded by the (properly grounded) mast my anemometer is mounted on. I would entertain thoughts of how to safely mount it higher. For anything in the past, it was usually a simple matter of something like a spark gap arrestor on the lead-in. I've no idea how to obtain the same protection with an active antenna like the Boltek uses...

Thoughts:

1.  http://www.lightningsafety.com/nlsi_pls/cone-of-protection-myth.html and http://www.wrh.noaa.gov/hnx/LightningMyths-1.pdf

2.  Regardless, I suspect that if lightning does strike the properly-grounded mast, I suspect there would be substantial induced currents in any conductor within perhaps 100 ft. or more.  [That is based on one incident of direct experience, where lightning struck a well-grounded metal tower near my house, and took out several electrical things within the house]

3.  If my "induced current" suspicion is incorrect, then consider:  lightning is much more likely to directly strike a well-grounded mast, than to strike something that is insulated (PVC pipe or whatever) mounted above the mast.  So, the "cone of protection" extends above the mast?

4.  Lightning striking any particular place is low-probability, and if it does strike, the effects are essentially unpredictable.  Therefore, I do what's reasonable (properly ground my tower), and accept that there will be some (unpredictable) damage in that low-probability event.

Oh, for the record, my Boltek antenna is mounted in a PVC "bubble" on top of a 10-ft PVC pipe that extends about 8 feet above my well-grounded tower (bottom part of a Hy-Gain 18HT).
« Last Edit: March 07, 2012, 10:03:57 AM by dalecoy »

Offline C5250

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Re: Relocate Boltek antenna on top of push up pole
« Reply #14 on: March 08, 2012, 10:05:42 PM »
Thoughts:

1.  http://www.lightningsafety.com/nlsi_pls/cone-of-protection-myth.html and http://www.wrh.noaa.gov/hnx/LightningMyths-1.pdf

When I mentioned "cone of protection" it was a reference to the cone below a properly grounded conductor, not just any tall object.

2.  Regardless, I suspect that if lightning does strike the properly-grounded mast, I suspect there would be substantial induced currents in any conductor within perhaps 100 ft. or more.  [That is based on one incident of direct experience, where lightning struck a well-grounded metal tower near my house, and took out several electrical things within the house]

Lightning protection is not designed to protect electrical or electronic devices within the structure from induced currents. It is designed to reduce the probability of a lightning strike. In fact, lacking an Empire State building class protection system, the typical lightning protection system would likely be vaporized if it actually took a direct strike. (Note that structures over 75' require a wholly different type of lightning protection system.)

3.  If my "induced current" suspicion is incorrect, then consider:  lightning is much more likely to directly strike a well-grounded mast, than to strike something that is insulated (PVC pipe or whatever) mounted above the mast.  So, the "cone of protection" extends above the mast?

This is incorrect, the excepted theory of lightning protection as defined by NFPA 780, UL 96A and LPI 175 is primary designed to drain any build-up of static charge, which may attract a direct strike. There is a brief outline here. Not exactly pointed out there, but I will point out that NFPA requires that conductors passing through an exterior wall of a structure must be electrically tied to the structures electrical ground.


4.  Lightning striking any particular place is low-probability, and if it does strike, the effects are essentially unpredictable.  Therefore, I do what's reasonable (properly ground my tower), and accept that there will be some (unpredictable) damage in that low-probability event.

This is true. All one can do is make them self aware of the issues and try to follow the current best practices.

Oh, for the record, my Boltek antenna is mounted in a PVC "bubble" on top of a 10-ft PVC pipe that extends about 8 feet above my well-grounded tower (bottom part of a Hy-Gain 18HT).

A PVC mast has always bothered me. As PVC will build-up a static charge and can not be properly grounded. While PVC is normally a dielectric, it will conduct a lightning strike.

Edit for spelling error
« Last Edit: March 08, 2012, 10:10:50 PM by C5250 »
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Offline dalecoy

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Re: Relocate Boltek antenna on top of push up pole
« Reply #15 on: March 09, 2012, 10:10:36 AM »

... There is a brief outline here.

Thanks for reminding me to re-read that reference.  I must admit that I don't conform to all of those recommendations (for instance, I just don't do thermal bonding of conductors, don't pay enough attention to bend radius, etc.). 

I did think this was a good reminder:
Quote
Lightning "prevention" or "protection" (in an absolute sense) is impossible. A diminution of its consequences, together with incremental safety improvements, can be obtained by the use of a holistic or systematic hazard mitigation approach...


...  Not exactly pointed out there, but I will point out that NFPA requires that conductors passing through an exterior wall of a structure must be electrically tied to the structures electrical ground.


That's not exactly what the NFPA requires.  If that were the requirement, then none of us would have electricity, wired telephones, or cable or satellite TV within our structures.

This discussion does raise an interesting question for the forum, of course.  How many reports have there been, of damage to Boltek antennas and/or connected computers, etc., due to nearby or direct lightning strikes?

Offline C5250

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Re: Relocate Boltek antenna on top of push up pole
« Reply #16 on: March 09, 2012, 11:46:54 PM »
Thanks for reminding me to re-read that reference.  I must admit that I don't conform to all of those recommendations (for instance, I just don't do thermal bonding of conductors, don't pay enough attention to bend radius, etc.). 

Understandable, exothermic welding is beyond the capability of most.

I did think this was a good reminder:
Quote
Lightning "prevention" or "protection" (in an absolute sense) is impossible. A diminution of its consequences, together with incremental safety improvements, can be obtained by the use of a holistic or systematic hazard mitigation approach...

Agreed! It is most difficult make most understand that the current best practices do not insure no damage from a direct strike. At best, they might help avoid a direct lightning strike. Lightning "protection" is still more of an art than it is science.


...  Not exactly pointed out there, but I will point out that NFPA requires that conductors passing through an exterior wall of a structure must be electrically tied to the structures electrical ground.


That's not exactly what the NFPA requires.  If that were the requirement, then none of us would have electricity, wired telephones, or cable or satellite TV within our structures.

No, but getting it to the details would require a lot of typing. Just trying to hit the main objective.

This discussion does raise an interesting question for the forum, of course.  How many reports have there been, of damage to Boltek antennas and/or connected computers, etc., due to nearby or direct lightning strikes?

It would be anecdotal, but I too would be interested in any such reports.

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Offline dalecoy

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Re: Relocate Boltek antenna on top of push up pole
« Reply #17 on: March 10, 2012, 11:16:38 AM »
I think we agree a lot more than we disagree. 

I'm just a bit more inclined to take a risk.  Also (with respect to lightning) my yard includes some tall trees, and my very-local neighborhood includes some relatively tall towers.  Those things make me feel like my Boltek-in-PVC isn't such an attractive target.

Mounting the antenna is a very individual decision, in consideration of the risk factors.

 

anything