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Amateur Radio Antennas - For discussion of all amateur band designed antennas and related accoutrements. This includes base, handheld, mobile and repeater usage. For commercial antennas on the amateur bands please use Commercial Radio Antennas below.

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  #21 (permalink)  
Old 07-18-2017, 8:45 AM
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Coyote,
Thank you for the link. Always enjoy reading up and learning more!
This project is about to stall for at least 2 weeks. Headed to the airport to pick up family that is visiting. I will get back to this in a few days or so. I will continue to read up on everything and will hopefully start getting everything ordered that i need for the project so that i can get this in the ground, and up and running in about 2-3 weeks!
Thanks everyone!

BTW, looking at some charts shows that our average lightning flash density is 12-15 flashes/mi2 per year. Neat resource, never thought about looking at something like that.

Last edited by 19dsniper; 07-18-2017 at 9:00 AM..
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Old 07-18-2017, 6:33 PM
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I didn't think I would/could write a sequel to my yesterday's post- but then a little serendipitous event occur'd this afternoon that gave me pause, and something else to write about.
.
This morning I and mi buen companera drove up to one of our remote sites in the Jemez Mountains (NM) to adjust a project. In town the temperature was a balmy 80 something, but by the time we crested the mountain site it was down to the upper 50's- What had started out as blue, clear skies were now turning dark and nasty. The wind was picking up, clouds were hanging on the peaks- the NOAA radio channel was alerting to thunderstorms thru out the region. The Monsoons have started.
.
We unlocked the cinder block equipment building and quickly completed what I'd come up there to do. I don't like to go up to these sites alone; meanwhile my companion, having come along as my escort, occupied herself with some equipment in another hut. It was while I was closing things up, it stared to hail- in heavy thick blowing ice---
.
Then--
.
"Ker- Accck !" followed by a split second "BOOOM"
.
The building lights went off simutaneously to a brilliant green flash that filled entire room. The first "Ker-accking" sound had come from some of the equipment and the heavy bulkhead on the wall-- a thick copper plate where all the cables, arrestors, powerlines meet and enter the building at the common ground junction.**
The Boom! was a power pole hit a millisecond before,- (the sound delayed.) But that flash of green light??.. God only know what that was; but it was inside that building with me!
The fluorescent lights were slowly flickered back on when my friend came bursting into the building.
.
"Lauri, are you all right?!" she stammer'd
.
"Yes, I think so" I replied
.
"I saw the pole down by the Blazer get hit--- I saw this Ghastly ! flash thru the door, from inside where you were... I didn't know what happen'd to you!"
.
"I'm fine, but lets get out of here" I said-- We hastily looked over all the equipment -- everything check'd ok.
.
Meanwhile a lot more thunder and flashes were spurring us quickly to lock up and head for the vehicle- the hail know turning to a cold slushy rain.
.
Normally one of us will jump out and lock the big steel gate on the site's road, but with the lightning striking all around, we just drove thru it. .
.
"We'll get the guys to lock it for us sometime.... later...."
.
So, how was Your Day??.......... (laughing )
.
________________________________________________
.
---------------Epilogue
.
"Is there something of a conclusion here, Lauri ?" you ask
.
"Yes there is"... now that I have had time to calmly think about what just happen'd to us (wine included.)

That brilliant green flash was, as far as I can determine----- that is, until some one goes to actually look- the power line surge arrestor. It's located inside, on the bulkhead as the lines enter the cinder block building.
These use a Zinc Oxide arc barrier- and remembering my chemistry, zinc burns the colour green. I may go up there later this week to verify this...
.
In the mean time, I am SOLD !... I am ordering two of them, one for Colorado and one for home here in NM.
.

.
.
..............................CF
.
** the 'floating ground' I mentioned before- a "one common" grounding point.

Last edited by Coyote-Frostbyte; 07-18-2017 at 6:38 PM..
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Old 07-18-2017, 10:35 PM
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http://www.hubbellpowersystems.com/l...n/EU1044-H.pdf
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Old 07-18-2017, 11:00 PM
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Louri, I love these stories, well written. Sorry if the high pressure we had here in So Cal moved in on you and your sidekick.

And what I hear from your writings, is all about proper grounding and bonding in the REAL world.

Reminds me of the saying: B plus to ground, Over...
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Old 07-19-2017, 4:02 PM
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Cmdrwill, RFI-EMI Guy--- Big Smiles, both
.
.
In the warm sunlight of another day, I have had a moment to reflect- and enquire about what happen'd yesterday.
.
This morning the Tech guys are all of the conclusion that the green flash we saw was not the destruction of the powerline surge arrestor-
.
And I agree. That electrifying moment spiked my judgement as well....
.
"It was something else, Lauri" is the general consensus.
.
"It was probably a flash over in the fluorescent light tubes... those arrestors aren't the Zinc Oxide types, but anyway--that arrestor may now be shot... plus who knows what else.... want one of us to go out and look at things?"
.
"Please ..... and close the gate for me?...."
.
_______________________________________________
.
So, later today I might have an answer- but it doesn't change my attitude about get power line arrestors. Since they need to be professionally installed, I'll go with what the electricians recommend.. but they are a definite on my list of the next things to-do's.
.
..............................CF
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Old 07-19-2017, 5:07 PM
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Could be copper that was burning, maybe a loose bonding cable or something. I have blown up small MOV types, using a variac, driving a very inductive load (Eddy current levitation). Quite a light show,

By the way, posted somewhere on one of my many news groups is a picture where a contractor ran his SUV into one of those pole type gates, the ones that are just a hinged pipe with a padlock chain on the free end. It was swinging back into the roadway.

It drove right through his grill, the engine compartment, and through the firewall and nearly impaled him. I have driven past those numerous times, sometimes they are painted brown to match the forest.
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Old 07-20-2017, 12:56 PM
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Chapter Three
.
The guys went up to Ground Zero early this morning. They went over everything in and about the huts and came back with a mixed report.
.
Want to hear it?.... (smiles.... But of course you do! .... )
.
"Lauri, we first looked at your power surge arrestor- it's status LED's were all green.. outside of those we have nothing else to assess its condition..... it is unlikely that's a false positive -- we've seen obvious failures and know those."
"B---- and I went over all the equipment, all the cables, connectors-- If you hadn't experienced what you did, no one would suspect anything.... sorry Boss. "
.
Later, they added--
.
"What we think happened was there was no direct hit on the power pole. If that occurr'd we would have seen something else, believe me. Barb probably saw the hit near the pole and what you both experienced was a secondary spike.... it came into the hut on the power line and was clamped by the bulkhead arrestor. "
.
"Those arrestors have a clamp voltage of approxiamtely 300 or so".. they (collectively) continued....
.
...."That 300 volt surge was quelch'd in the MOV's of the power strips and all various protective circuitry in the equipment, and it went harmless to ground. The fluorescent lights only have the bulkhead arrestor- and they experienced that temporary surge- and you saw them flash."
.
"At least that's as good a your going to get it from us..... but hey, I've got an idea...!" said B----.
.
"There are forecasts of thunderstorms all thru the week- it going to be really lively up there. Why don't you and Barb go back to the site and see if you can experience a repeat. This time-- take video recorders to capture what happens."
.
Smart A**'s......
.
______________________________________
.
So, if you've followed my little adventure this far, that's it--- I now leave you to form your own conclusions. We are Not !, however, going to take suggestion to sit out another storm up there to "see what happens."
.
.
...........................CF
.
.
________________________________________________
________________________________________________
.
Oh.... and
The Gate... I never want to get close to their likes during electrical storms... the above account, an obvious reason. That site has this massive welder's master piece- its made of 6" steel pipe that swings on huge hinges. It takes us weaker sex quite a bit of effort to open and close these site gates- they were erected to stop a Panzerkampf... No danger of driving into one; they are so festooned with government warning signs that only the most impaired of drivers will fail to see them.....so unlike the gates of the US Forest service...Oh, that's a different story entirely... (voice of experience....smiles)

Last edited by Coyote-Frostbyte; 07-20-2017 at 1:04 PM..
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Old 07-20-2017, 4:52 PM
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The most frighting lightning event I ever experienced was when lightning struck a car directly ahead of me in traffic. Nobody stalled or burned to a crisp, but I imagine the AM/FM radio in that car was toast. This was 1980's so no sensitive electronics to fry. Oh, I was in a plane once that got hit, I didn't notice but the pilots did mention it on the PA. Single point bonding saved the day.
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Old 07-20-2017, 7:05 PM
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Lauri, we're all happy and your BFF are safe!

We'd miss your stories!

I have a couple of OT for you in the PM's!
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Old 07-22-2017, 4:53 PM
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25 years ago I was offered a 60 foot Rohn that have been standing for 20 years already. All I had to do was take it down. I borrowed a jim-pole and took it down on a Saturday morning. A good friend of mine who owns an excavating company brought his backhoe over. We did a little hand digging and then lifted the base, concrete and all, out of the ground. When we got to my house with it, we dug a hole and suspended the base with one section attached in the hole while we backfilled around it. We soaked and compacted the soil while checking for plumb. It is free standing at 60 feet. Being only 4 miles from the lake Michigan shore near Holland, MI, we get our share of winds. Just because your friends tower is 100 feet doesn't mean you have to put it all up. I think the flexibility of adding or changing antennas that a tower will give you is worth the effort. As well as Rohn's are made, A visual inspection is more than adequate imho. I think the use of a utility pole this will be regretted down the road.


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Old 07-29-2017, 11:39 AM
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Just a quick update. Like i said, this was going to fall off for a little while because of company being at our house for a while. I should be able to get back to this next week.

I spoke with the power company guys and asked how much beer it was going to cost me to get them to drop the pole in the ground for me. I got a good laugh out of it and was told that i would have to call and talk to the supervisor. I am bing told that it all depends on time of day, who i speak with etc. I was told that sometimes the answer is "Yes, no problem", and that other times they are told that they aren't allowed to do it because of OSHA regulations. I honestly think it all depends on what your last name is, at least in our little town.

I also called a guy out of waco that installs ROHN antennas. His prices are about $25 higher per section than what i can find online at DX and a few other places. BUT, DX wants $99 shipping on just one section. Im not sure if he will let me purchase from him at that price, and NOT have him install it. I asked him if he had done one before for HAM operators and if he grounded them. I didn't feel too confident when he replied that he hasn't done any before for any "CB" guys and that it shouldn't need to be grounded... I find that scary and unprofessional to say the least. Apparently most of what he installs on them are TV antennas for people out in the country side, but it doesn't matter whats on there, it needs to be grounded.

Rant over, I found a "stocking dealer" of Rohn towers in Waco, and i may drive out there next week and speak with them. I know it started at Telephone pole mast antenna, but I'm just looking at a back up plan if the current one falls thru. We have an auger and some heavy equipment here at the farm, but i don't want to endanger myself or family that would have to help me put it in the ground if we had to do it ourselves. I wouldn't even ask. A 40 foot telephone pole isn't something you just toss in the ground.

Thanks everyone for all your help and recommendations. I will be back soon.
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Old 07-29-2017, 1:59 PM
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Texas Towers in Richardson is a huge tower dealer and usually has great pricing.
prcguy


Quote:
Originally Posted by 19dsniper View Post
Just a quick update. Like i said, this was going to fall off for a little while because of company being at our house for a while. I should be able to get back to this next week.

I spoke with the power company guys and asked how much beer it was going to cost me to get them to drop the pole in the ground for me. I got a good laugh out of it and was told that i would have to call and talk to the supervisor. I am bing told that it all depends on time of day, who i speak with etc. I was told that sometimes the answer is "Yes, no problem", and that other times they are told that they aren't allowed to do it because of OSHA regulations. I honestly think it all depends on what your last name is, at least in our little town.

I also called a guy out of waco that installs ROHN antennas. His prices are about $25 higher per section than what i can find online at DX and a few other places. BUT, DX wants $99 shipping on just one section. Im not sure if he will let me purchase from him at that price, and NOT have him install it. I asked him if he had done one before for HAM operators and if he grounded them. I didn't feel too confident when he replied that he hasn't done any before for any "CB" guys and that it shouldn't need to be grounded... I find that scary and unprofessional to say the least. Apparently most of what he installs on them are TV antennas for people out in the country side, but it doesn't matter whats on there, it needs to be grounded.

Rant over, I found a "stocking dealer" of Rohn towers in Waco, and i may drive out there next week and speak with them. I know it started at Telephone pole mast antenna, but I'm just looking at a back up plan if the current one falls thru. We have an auger and some heavy equipment here at the farm, but i don't want to endanger myself or family that would have to help me put it in the ground if we had to do it ourselves. I wouldn't even ask. A 40 foot telephone pole isn't something you just toss in the ground.

Thanks everyone for all your help and recommendations. I will be back soon.
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Old 07-29-2017, 3:29 PM
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Quote:
Originally Posted by 19dsniper View Post
Just a quick update. Like i said, this was going to fall off for a little while because of company being at our house for a while. I should be able to get back to this next week.

I spoke with the power company guys and asked how much beer it was going to cost me to get them to drop the pole in the ground for me. I got a good laugh out of it and was told that i would have to call and talk to the supervisor. I am bing told that it all depends on time of day, who i speak with etc. I was told that sometimes the answer is "Yes, no problem", and that other times they are told that they aren't allowed to do it because of OSHA regulations. I honestly think it all depends on what your last name is, at least in our little town.

I also called a guy out of waco that installs ROHN antennas. His prices are about $25 higher per section than what i can find online at DX and a few other places. BUT, DX wants $99 shipping on just one section. Im not sure if he will let me purchase from him at that price, and NOT have him install it. I asked him if he had done one before for HAM operators and if he grounded them. I didn't feel too confident when he replied that he hasn't done any before for any "CB" guys and that it shouldn't need to be grounded... I find that scary and unprofessional to say the least. Apparently most of what he installs on them are TV antennas for people out in the country side, but it doesn't matter whats on there, it needs to be grounded.

Rant over, I found a "stocking dealer" of Rohn towers in Waco, and i may drive out there next week and speak with them. I know it started at Telephone pole mast antenna, but I'm just looking at a back up plan if the current one falls thru. We have an auger and some heavy equipment here at the farm, but i don't want to endanger myself or family that would have to help me put it in the ground if we had to do it ourselves. I wouldn't even ask. A 40 foot telephone pole isn't something you just toss in the ground.

Thanks everyone for all your help and recommendations. I will be back soon.
If your auger is sufficiently large enough to bury a tower section, why not explore the possibility of erecting a short tower that way. You will have to determine the amount of concrete required for the tower foundation. Drill deep enough to backfill some drainage gravel at the bottom so that the tower and base can drain any rainwater or condensation from the legs. You will find a short tower easier to work with for antenna erection than a phone pole. Easier to climb, easier to ground, easier to mount antennas, brackets and cables.

The Rohn catalog is helpful on design and assuming you have "normal soil" you can estimate from that. Also, if you can plan ahead, you might be able to add sections later and guy them off should you desire greater height later.
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Old 07-29-2017, 8:50 PM
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So, I called my buddy again. He is still offering a 100 ft tower for whatever I think is fair trade. If you guys have any idea what "fair" would be, or $ amount, please let me know. Right now I think I will actually go ahead and pick up this 100 ft tower and use it instead of the pole. I will look at it and bring pictures back later this week and post them here. All he knows is that it was a 100 foot, commercial repeater tower that use to be used by the water department to send data back to their main station. It was professionally removed. He has 7 sections at his house and another 3 sections at another property he has. It also has a flat mounting plate that is tilting. He says that if I connect all 10 foot sections that I should be able to use the tractor or bull dozer at our house to pull it up with the tilting base and "put the pin in it". One it look at it and find the model number and maker I will update here and do my research on the tower itself. I think I may go 50 feet here and another 50 at another property. I tried sweet talking the wife into letting me go 100 all at once here at the house and she said no, so I will take 50 for now. Who knows, maybe I can sneak up 10 foot sections at a time and see how long it takes for her to catch on!

Will update on Tues or wed. Once ice had a chance to look the tower over and take pictures.
Now to figure out fair trade!
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Old 08-03-2017, 11:32 AM
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Ok, So a quick update.
I went out the other day and took a look at the tower. It appears to be an older Rohn 25 in good condition. There are 9 standard sections and then the 1 top section. It also has a tilting base with it. The base says "BPH 25" it doesn't say 25G. Im guessing this is the old Rohn 25 tilting base that they quit making a number of years ago. I really do want a tilting base on it so that i can swap antennas, do maintenance, or even lower it if i know we have really nasty weather coming in. It may not be ideal, but if i know we are predicted to get really high winds, i just might lay it over to protect it some. I looked at our wind zone maps for our area and we are at 70 MPH. That would allow me to make it freestanding up to 40 feet which is what my original intent was. I think i will keep the extra masts for another property and get 2 out of them. My wife is on board with 100 feet, but not if i have to guy it out. I can't take over the back yard with our young kids wanting to play out there. 40 feet will still work really well for what i want to do i think. I was able to make a trade that we both feel is fair, in fact, he believes its more than fair as he is also going to deliver it to me tomorrow. I am going to slow down on the instalation of the tower though. I want to go ahead and take the exam first so that I'm not tempted to get on the radio too early. Im a big enough man to admit that once its up, i will want to get on the radio. So, i better get the license before installing it. That way i can also test it as soon as it goes up to make sure my SWR and everything is good to go.

Any ideas as far as antenna at the height of 40 feet, freestanding? I was originally looking at the Diamond X510HDN and think i will still go that route. Does anyone know if this antenna will be alright on a Rohn 25 freestanding at 40 feet? If i have to i may bracket the antenna to the side of the house, but I'm trying my best to keep everything off the house and not attached to the home in any way. I know it would be better to bracket to the house, but should i be ok without bracketing it?

I will update with pictures when i get the antenna to the house tomorrow. I may dump the tilting base that it comes with and update to a Normsfab tilting base. Does anyone think its necessary, or should i be good with the Rohn BPH 25?

Thanks again everyone for all your help. I will keep this going till i get this antenna up and on the air.
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Old 08-03-2017, 11:59 AM
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I think the Rohn data will tell you that tower should be guyed at 40ft tall even without an antenna on top. I personally believe it will be fine free standing with the base in an engineered concrete foundation but I would never recommend that to someone else.

With a modest foundation and tilt over base and a house bracket at 10 to 15ft it should be fine for what you are doing. If you go with a tilt over base you can forget about free standing on that model.
prcguy

Quote:
Originally Posted by 19dsniper View Post
Ok, So a quick update.
I went out the other day and took a look at the tower. It appears to be an older Rohn 25 in good condition. There are 9 standard sections and then the 1 top section. It also has a tilting base with it. The base says "BPH 25" it doesn't say 25G. Im guessing this is the old Rohn 25 tilting base that they quit making a number of years ago. I really do want a tilting base on it so that i can swap antennas, do maintenance, or even lower it if i know we have really nasty weather coming in. It may not be ideal, but if i know we are predicted to get really high winds, i just might lay it over to protect it some. I looked at our wind zone maps for our area and we are at 70 MPH. That would allow me to make it freestanding up to 40 feet which is what my original intent was. I think i will keep the extra masts for another property and get 2 out of them. My wife is on board with 100 feet, but not if i have to guy it out. I can't take over the back yard with our young kids wanting to play out there. 40 feet will still work really well for what i want to do i think. I was able to make a trade that we both feel is fair, in fact, he believes its more than fair as he is also going to deliver it to me tomorrow. I am going to slow down on the instalation of the tower though. I want to go ahead and take the exam first so that I'm not tempted to get on the radio too early. Im a big enough man to admit that once its up, i will want to get on the radio. So, i better get the license before installing it. That way i can also test it as soon as it goes up to make sure my SWR and everything is good to go.

Any ideas as far as antenna at the height of 40 feet, freestanding? I was originally looking at the Diamond X510HDN and think i will still go that route. Does anyone know if this antenna will be alright on a Rohn 25 freestanding at 40 feet? If i have to i may bracket the antenna to the side of the house, but I'm trying my best to keep everything off the house and not attached to the home in any way. I know it would be better to bracket to the house, but should i be ok without bracketing it?

I will update with pictures when i get the antenna to the house tomorrow. I may dump the tilting base that it comes with and update to a Normsfab tilting base. Does anyone think its necessary, or should i be good with the Rohn BPH 25?

Thanks again everyone for all your help. I will keep this going till i get this antenna up and on the air.
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Old 08-03-2017, 12:18 PM
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The Rohn Manual that i downloaded states that the Rohn 25 is capable of free standing (un guyed) at 40 feet in a 70 mph wind zone with a rating of 1.5 Ft2. and at 30 foot freestanding in a 90 mph zone at 1.7 FT2.
I THINK I'm reading this correctly to state that i should be ok to add a concrete base and free stand the antenna at 40 feet as long as i keep the wind load of the antenna at or preferably below 1.7 Ft2. I will be calling diamond to figure out the best antenna that is 1.7 or less.

Last edited by 19dsniper; 08-03-2017 at 12:19 PM.. Reason: had to correct the numbers
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Old 08-03-2017, 1:12 PM
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If there is someone good with math, please help me out as I'm getting different numbers. I have calls into both Rohn and Diamond trying to figure out what the wind load is.
If my math is correct, the diamond X510HDN has a wind load of 2.752. According to Rohn, i need to be at or below 1.5 at 40 feet, or 3.6 at 35 feet. So, it looks like i will not be able to go to the 40 foot mark.
Do you think i would be better getting a smaller, lower gain antenna higher, or a higher gain 5 feet lower?
Also, does anyone know if the height is measured from the base of the antenna or from the tip of the antenna when it comes to Rohn heights? Meaning, if it states 40 feet, is that to the base of say a 17 foot antenna, or to the tip of that 17 foot antenna? If its to the tip, it looks like i can only go 2 sections of Rohn 25.
Am i over thinking things here? I wish i would hear back from Rohn.
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Old 08-03-2017, 1:26 PM
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Quote:
Originally Posted by 19dsniper View Post
If there is someone good with math, please help me out as I'm getting different numbers. I have calls into both Rohn and Diamond trying to figure out what the wind load is.
If my math is correct, the diamond X510HDN has a wind load of 2.752. According to Rohn, i need to be at or below 1.5 at 40 feet, or 3.6 at 35 feet. So, it looks like i will not be able to go to the 40 foot mark.
Do you think i would be better getting a smaller, lower gain antenna higher, or a higher gain 5 feet lower?
Also, does anyone know if the height is measured from the base of the antenna or from the tip of the antenna when it comes to Rohn heights? Meaning, if it states 40 feet, is that to the base of say a 17 foot antenna, or to the tip of that 17 foot antenna? If its to the tip, it looks like i can only go 2 sections of Rohn 25.
Am i over thinking things here? I wish i would hear back from Rohn.
Go for the height. Rohn is probably specifying to the force applied directly at the mounting point measured above ground. The antenna itself, has a survival rating. complicating this, is that the feedline has a wind load, but it is distributed over the height of the tower. It will probably be negligible in your situation. But if it worries you, the feedline should be tied close to one of the tower legs which will reduce its effect somewhat.

Back during Hurricane Andrew I lived 2000 feet from Biscayne Bay in an area that received some very high wind velocities I think 140 MPH (edit 115 gusting to 164 MPH at the nearby NHC building) . Trees were toppled, but buildings spared. I had a 9 dBd fiberglass Decibel Products UHF base station antenna, some 17 feet long atop a 2 inch galvanized water pipe that was two sections totaling 20 feet long, buried in a bit of concrete and anchored to the gable of the house. Next to it, a 1 1/2 inch TV mast 20 feet tall with a small RV television antenna (wing shaped) and rotator similarly fastened to the gable . After the hurricane the base station antenna was intact, the gable mount attachment (a weak point) merely pulled away. The TV antenna was another story, it was a mangled mess, the mast bent over into the neighbors yard.

My point being, that a cylinder antenna might impart less force than an irregular antenna like a yagi.
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Last edited by RFI-EMI-GUY; 08-03-2017 at 1:47 PM..
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Old 08-03-2017, 1:51 PM
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I would think on getting a better aka commercial antenna than the Diamond Comet junk The Diamond will fail in the winds, and only have a 19 gauge steel wire with piss poor copper plating for an element.. not to mention the very thin fiber housing.
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