First tower/mast. Location and material.

[19dsniper]

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.

Is there one that you would recommend that has similar gain? Im not familiar with any commercial equipment. A wide band version would be nice so that i could still use MURS or something similar when my kids are out and about on the property. We are currently using some Baofeng uv-5r programmed with the FRS GMRS bands in them. Even at 5 watts, they won't reach all of our property. It would be nice to get a commercial wide band antenna that could keep SWR down in the higher frequencies for that application. But then again, with that much gain, i don't think it would make a difference when they are only 1/2 mile away. I have a feeling they would still be under the radiation pattern.

 

[19dsniper]

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.

After speaking with someone earlier today, i was told that they don't even measure wind load for vertical antennas because its so low. Turns out i was wrong earlier and the wind load is actually 0.5026 ft2.
You are correct on the fact that a cylinder imparts less force. WAY less apparently! I grew up in south Florida myself and was in miami at the time of hurricane Andrew. I remember watching out the window as trees were ripped out of the ground and thrown. Then later saw those same trees floating down the street. We drove thru homestead seeing if we could be of any help as soon as it was over. Talk about a disaster! Anyways, it sounds like this is going to be similar to your UHF base station antenna. This antenna is 17.2" long. I was previously looking at the X700 that is 24 feet at 13 dbi at uhf and 9.3 on vhf. I think that one may be a little overkill and the Diamond rep actually recommended the X500 heavy duty because of wind.
Thank you for the info. It has helped me out a lot!

 

[cmdrwill]

I hope you do not really believe those so-called gain numbers. And will not cover the MURS and Ham bands and GMRS you mention.

 

[19dsniper]

I don't believe that they are 100% accurate. I look at them like published velocities of ammunition. They are never correct unless in specific conditions and with specific equipment. However, i do use them as a baseline of sorts. An antenna that is published as having only 3 DBI is most likely still going to have less gain as one publishing a gain of 13 dbi when looking at reputable companies. Do i believe that they are really going to get the published 13? No, but i do believe that it will still be higher than the one listed as only 3. I have no idea of how to actually measure gain myself. That is something that is way over my head and most likely most end users. But, i am still looking at the published numbers and reading as many reviews as i can. That and other peoples opinions are the only thing i have to go off of.

 

[19dsniper]

I hope you do not really believe those so-called gain numbers. And will not cover the MURS and Ham bands and GMRS you mention.

A commercial antenna should cover those frequencies just fine. At least from my knowledge. I have one now that is a roll up Jpole in the attic that is tuned for optimal resonance on frequencies 151.820 - 154.600 and 462.575 - 467.725. I could always just move this outside on a mast and use that with the portable.

 

[RFI-EMI-GUY]

Commercial antennas are rated in dBd because that is referenced to a dipole and NIST has methods to certify dipole gain.

Ham antennas are in dBi which sounds better than same antenna in dBd because the number is 2.15 dB greater.

dBi is referenced to isotropic . Not much in the physical world, apart from perhaps the sun is an isotropic radiator. Microwave dish antennas are referenced in dBi because their pattern gain can be determined from a power concentrated in a section of a sphere.

Then you have the bandwidth dilemma. It is a challenge to produce a wideband antenna with gain. Colinear antennas might be spec'd as wideband but you experience pattern tilt at one end of the band versus the other. As a consumer, You pretty much have to hope the VSWR is ok and hope for the best.

 

[19dsniper]

I never knew that commercial antennas were rated in dBd. Thank you for sharing that. Do you have any pointers in how to select a good antenna for a base station for long range simplex? Im not interested in a directional antenna just yet. I may add one in the future. I only knew that dBi was isotropic, but thats about where my knowledge ends on that one. Lol

Thanks again, more to read up on! I have been playing with Radio Mobile Online This has given me a better understanding of what to hopefully expect. At least its fun to play around with. It is showing that if i was to go up the additional 60 feet to take my current plans to 100, that i wouldn't really gain a whole lot in the direction that I'm most interested in. It will give me more coverage to the South East and not really a whole lot. So it looks like 40 feet will get me what i need. If anyone is looking for a way to spend half a day playing, get on there and start messing around with stuff. Its a lot of fun!

 

[19dsniper]

Quick update. We were unable to get our schedules to match up the other day and get the tower moved. We did however get it moved today. I may update with some pictures tomorrow. I will be getting concrete soon and i am also looking into a different tilting base for the Rohn 25. I put in a call to NormsFab and am waiting a call back. I still need to pick up the 1/2"x12" bolts for the concrete. I did go ahead and pick up an 8' grounding rod and hardware. I still need to get the copper grounding wire that will go from the tower to the grounding rod. I may just go take some off of the power pole i planned on using earlier. I am still far from having everything i need. I still need to order a polyphase, coax, etc. It will still be a while, but its moving along.

 

[19dsniper]

I have run into some health issues from combat injuries i sustained 9 years ago. So, for now, this project has stalled. I will continue once i get things back on line. Thanks to everyone for all your help.

 

[19dsniper]

Ok, so I'm back at it again.
Quick update. About 2 weeks ago i ended up going blind in my right eye for a short period of time, about 4 minutes. It was long enough to scare the crap out of me and send me to the ER. To make a long story short, Due to my age, health, etc. The Dr. believes that it is some how related to some old brain injuries i sustained in 2008. Needless to say, i took some down time to rest and see how things will go. So far, so good. So that leads us back to this project.

I have already dug the hole for the concrete to be poured. First hiccup that i have run into is that the local concrete companies will only deliver loads of 3 yards or larger. So, this leaves me with buying LOTS of bags and mixing by hand in a wheel barrow. We are expected to start getting some really bad weather tomorrow and later this week, so i don't want to start concrete today. Once the bad weather passes, i will go ahead and start mixing and pouring concrete.

In the mean time i am going to do some tower maintenance. I am trying to decide between priming and painting the tower, or re-spraying with cold galvanize. I think the prime and paint will look better, but what holds up longer?
I know i need to get a primer and paint that is compatible with galvanized steel. In fact after speaking with ROHN today i was told that it may not even matter because of the age of the tower. It is believed that the tower may have aged to the point that the Zinc is now neutralized. So i was told that i could use a primer, preferably an acid etch primer, and a good paint. I looked at the local tractor supply at some of their farm paints used to paint tractors and galvanized steel feed bins and the like. I may go with something like that.

So, for now, i am going to locate some primer and paint and get this thing ready for concrete.
Any recommendations on brand or type of paint from anyone?

Thanks again everyone, sorry it stalled there for a while.

 

[prcguy]

I've never seen any paint or primer that will last over galvanized, even if its rated for that. I've had multi million $$ satellite antennas where the paint peels off in a few years and they were properly treated and painted over galvanize.

Cold galv is ok for touch ups but I would not cover an entire object with it.
prcguy

Ok, so I'm back at it again.
Quick update. About 2 weeks ago i ended up going blind in my right eye for a short period of time, about 4 minutes. It was long enough to scare the crap out of me and send me to the ER. To make a long story short, Due to my age, health, etc. The Dr. believes that it is some how related to some old brain injuries i sustained in 2008. Needless to say, i took some down time to rest and see how things will go. So far, so good. So that leads us back to this project.

I have already dug the hole for the concrete to be poured. First hiccup that i have run into is that the local concrete companies will only deliver loads of 3 yards or larger. So, this leaves me with buying LOTS of bags and mixing by hand in a wheel barrow. We are expected to start getting some really bad weather tomorrow and later this week, so i don't want to start concrete today. Once the bad weather passes, i will go ahead and start mixing and pouring concrete.

In the mean time i am going to do some tower maintenance. I am trying to decide between priming and painting the tower, or re-spraying with cold galvanize. I think the prime and paint will look better, but what holds up longer?
I know i need to get a primer and paint that is compatible with galvanized steel. In fact after speaking with ROHN today i was told that it may not even matter because of the age of the tower. It is believed that the tower may have aged to the point that the Zinc is now neutralized. So i was told that i could use a primer, preferably an acid etch primer, and a good paint. I looked at the local tractor supply at some of their farm paints used to paint tractors and galvanized steel feed bins and the like. I may go with something like that.

So, for now, i am going to locate some primer and paint and get this thing ready for concrete.
Any recommendations on brand or type of paint from anyone?

Thanks again everyone, sorry it stalled there for a while.

 

[19dsniper]

Any recommendation on what should be used on an older tower? Or should i just leave it alone?

I have surface rust on some sections. It was laying down on some pallets for the last few years. I have looked it over and even used a borescope to check inside as far as it will reach. Its not long enough to run past 5 feet (longest stretch from each end of a single section) but so far everything inside looks good. Outside has a few spots of some surface rust in a few small spots. I was going to get it cleaned up with a wire wheel with my hand drill. Then i was going to prep and seal it to prevent any further spreading. I spoke with ROHN about it and of corse they recommended a "Blended Vinyl Acrylic Emulsion" after prepping the surface with a mix of "copper chloride/copper Nitrate/ Sal Ammoniac, Muriatic acid" and then a rinse and dry before applying the Blended Vinyl.

I was hoping there was a much simpler solution. This is what prompted my call to them this morning and the comment made by them that a tower of its age was probably already unprotected due to the age of the zinc and it being "neutralized over time". I told them i was hoping that there was product that was available local for me to purchase as their specialty Blended Vinyl stuff was extremely expensive and only available in certain areas, which he verified it was not available here. He then recommended that i go speak with someone at either Sherman Williams or Rustoleum and to pick a product that is rated for outdoors, and does not contain aluminum.

After speaking with Rustoleum they recommended that i use a product know as "Aluminum Primer, 8781" that is used on aluminum or galvanized items. Then a top coat of whichever color i want.

Maybe i will use the Zinc Cold Galvanizing Spray on the problem areas and leave the rest alone. I was just hoping to ward off any future problems, and i will admit that i am a fiddler and want to mess around with this stuff while its on the ground and hasn't been installed yet. If there is something i can do to improve its longevity before it goes up, i would like to do it.

Thanks again PRCGUY!

 

[sdu219]

I just put on some rubber gloves with a bucket of silver rustoleum and a sponge. 4 years still looks great.

 

[RFI-EMI-GUY]

You might look up the American Galvanizers Institute, I think that is the name. They publish a ton of related information. Galvanization is good for about 25 years. I would look the tower over very carefully and note any rust through pinholes, or cracks at welds.


Get a rubber mallet and bang the tower legs to see if any sheets of rust fall out when you tip the sections up. Also run water through to dislodge and dirt or telltale rust scales.

If all looks solid, Zinc cold Galvanization paint would be a good touch up. Surface prep is a must.


Regarding the concrete load. You can always pour a parking slab or patio to justify a larger load. Mixing by hand is tough I have done that, never again. Hire a couple of helpers so you don't wreck your health.

Sent from my SM-T350 using Tapatalk

 

[RFI-EMI-GUY]

I've never seen any paint or primer that will last over galvanized, even if its rated for that. I've had multi million $$ satellite antennas where the paint peels off in a few years and they were properly treated and painted over galvanize.

Cold galv is ok for touch ups but I would not cover an entire object with it.
prcguy

When I put up my US Tower TX489MDPL, the mast raising fixture which was not galvanized and needed painting.

I had a pro do it with some common zinc based industrial paint, battleship grey. Stuff you would paint electrical gear, gear boxes, motors and pumps with. It looked fantastic and held up very well while I owned it. That might work over aged galvanized metal. I can't recall the brand. I think there was a coat of zinc based primer applied first.

Sent from my SM-T350 using Tapatalk

 

[SCPD]

This Spring I put up a used tower. Well, I hardly did it- my rancher-neighbor who leases some of my pastures did the whole thing for me. He had a 45 foot section of the bottom of an AM radio station tower- he's never told me why or to what purpose he'd intend'd that tower- but tiring of it being around, gave it to me. The tower came with the ceramic insulator base, which was what I particular was interested in, for I wanted it as a base insulated vertical.
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My neighbor sent it over with a couple of his sons and a back hoe. In minutes, they'd scoop'd out a hole for the base, and three others for its guy lines anchors. They also brought along a big portable cement mixers and a flat load'd truck of bagged concrete.
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Knowing nothing about concrete mixing and preparation, I watch'd fascinated at how these cowboys placed that base so quickly and efficiently. That cement mixer was the magic ingredient- for I can only imagine what back breaking work mixing it all by hand would be.
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"Ma'm, once you start pouring it, it has to be continuous- no layering, or it won't be solid"
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........was the lesson I took away that morning.... plus have a Big mixer and guys that know what they are doing....
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Several days later, the concrete set- they were back. The insulator section was placed, and with that back hoe, the remainder of the tower was swung up on to it, bolted together and the guy lines secured. They had it completed in less than an hour.
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When I ask'd their father what I owed him for all this, he just said
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"Oh, just pay me for the cement"---
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I did him better than just the cement; there's no rent on those pastures for quite awhile.
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_________________________________________________
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We are lucky out here- things don't rust the way they do in other parts of the country. A galvanized Anything last and lasts- I have some horse troughs that must be a century old that could still pass for (nearly) new. My above example'd tower is older than I am- it is riveted angle iron steel, galvanized and painted a ghastly orangy-red (red lead??)- but without a speck of rust.
I couldn't say that for towers I have seem in other parts of the country, especially if they are hollow legged designs that can accumulate water in their legs. They may appear solid but they are anything but.
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At work the fellows that do towers have told me many times to be very careful around any old towers- and when they take one down, it almost always goes to the scrap dealers. They have some blood curdling tower-tales...
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That, and for a number of other reasons- I never climb them any more.
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........................CF

 

[RFI-EMI-GUY]

At work the fellows that do towers have told me many times to be very careful around any old towers- and when they take one down, it almost always goes to the scrap dealers. They have some blood curdling tower-tales...
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That, and for a number of other reasons- I never climb them any more.
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........................CF

Down here in Florida, on the coast. one of my customers had a >350 foot guyed tower Rohn 80 if I recall. The lamp went out and a tower crew sent up to replace it. The crew got to about 200 ft level and retreated.

They had some nasty pictures of the legs almost totally rusted through. Not sure what was holding it together. It had to be demolished.

Just before hurricane Andrew. At Miami Dade Police, I was taking a shortcut from the 911 center parking lot where a 300 foot guyed tower was centered (amongst cars and pedestrians.) to the EOC shelter. There in the picnic area is a guy anchor. I looked at it and the huge nut holding the cable end/eye was almost rusted away entirely. I mentioned this to my customer and within a week, that tower was taken down to 80 feet and re purposed for back up links and microwave only.

These were all pretty old towers, but their are a lot of them.

A newer self supporting tower simply toppled over in a storm. It pulled all of the rebar from the sandy soil. There was only about 5 feet of concrete encasing that leg, though a hole and steel rebar cage extended far deeper into sandy soil . Apparently the hole collapsed during the pour and the contractor did not see fit to redo the job correctly. He would have had to send back several loads of concrete so you can be sure he knew there was a problem.

 

[N4GIX]

There was only about 5 feet of concrete encasing that leg, though a hole and steel rebar cage extended far deeper into sandy soil . Apparently the hole collapsed during the pour and the contractor did not see fit to redo the job correctly. He would have had to send back several loads of concrete so you can be sure he knew there was a problem.

That is precisely why I had my crews place round liner tubes around the rebar. The liner prevented collapsing holes and guaranteed a solid plug of concrete!

 

[SCPD]

Smiles, RFI.....
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There is nothing like your tale to evoke antenna stories. I fear they may be scaring some reader..... but that's intention, No?.... (smiling)
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At the outset, I'd say to anyone thinking of using an old tower - really know what you're doing. If I recall from memory, one of the big commercial manufacturers specifically warns against it, not to mention the dangers in disassembling a standing tower. All that said, I just put up one, although only 40-some feet high.
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OMG, what a nightmare to climb 300 feet high and have a rott'd section buckle!
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I think this is about all I can say on the subject... it really doesn't need much embellishment-- A good sense of imagination fills in the rest.
----- Oh, except for one or two of my anecdotes.....
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The first tower story I only saw after the event. It was in Florida, east of Tampa. My geographical knowledge of Florida is very limited, but I think it fell within the boundaries of "Sink Hole Alley." Well, it doesn't take much imagination as to what became of the tower one of our contractors installed. One day it was a 100 foot tower; overnite it became a 10 footer.
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"Barbi," my friend and colleague, on visiting the site, report'd
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"Damn antenna, Heap Gone!"
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The other, a second one (Oh, I've plenty of others but I'll spare everyone ) was during a stay out on a site in the Marshall Islands. We had a DoE research station on one of the northern atolls, and at this station there was a big log periodic a-top of a 80 foot tower (for HF radio.) On this occasion, except for the station manager and his wives (yes, you read that right,) I was by myself that tour.
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We'll call him Bill. Bill, the Manager- he admonish'd me; "Lauri, Do Not to turn that beam!!"
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Why, he didn't elaborate , but I think he mumbled something about "salt spay" and "corrosion."
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Well, its not what you're are thinking- I didn't have to touch it. A tropical storm brew up a few nites later; ---- it was a very dark, and I was alone in the radio "shack," listening to shortwave. The howling wind was causing the quonset hut roof's cables tie-downs to actually sing.
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Then began a series of crashes, each louder that the next, as big, heavy things fell on top of that hut. The screaming wind, the pitch black night, and huge, thudding objects had me scared! I knew right above me a mammoth beam was about to coming crashing down thru the roof. I wasn't going to wait for that!
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Out the hut door --- running across the courtyard towards my quarters, just being miss'd an element of that beam that came hurdling down at me............
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"Ahi !!... Mi Querido!" ... my thoughts all in a jumble ....
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It was now very clear why these stations had body bags among the other items no one talks about.
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The next morning the tower and its beam were nothing more than a tangle of aluminum, guy wires and cables, draped all over the radio "shack."
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Bill's comment ...."Humpf- salt spray does that every time."
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................................CF
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[RFI-EMI-GUY]

The manufacturers like to scare you into buying new. I bought a used US Tower TX489MDPL and proceeded to completely rebuild it. Talking with the guy at US Tower (Bruce or Barry? something with a B. I thought he might be a Russian) was like pulling teeth. They were happy to accept my cash, but dispensing information? No way.

Are you sure you didn't turn that antenna, just a wee bit for better reception? Really, Bill should have had that thing dynamited at the first sign of troubles.