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Post by whitetail on Jul 14, 2015 20:31:49 GMT -5
I been wanting to put up a base antenna now for awhile, I will admit that Iam afraid of lightning! Who isnt? Last fall I bought a new Imax 2000 and put the base at 20' off the ground, attached to 2 pieces of 10'Pipe strapped to my porch post. I took it down in april when the storm season started. It worked great swr was flat and I talked all over that winter. My goal was to put up my 40' tower I have had in the shed now for 4 yrs, and fly the Imax on top of that!! That thing would rock right? But the question is that now matter how good of a ground and arresters you have you are still vaurnable to a strike, correct? I was going to ground each leg of the tower to a 8' ground rod. will this be enough, along with a lightning arrester? I would like to have this station up all the time instead of putting it up in the fall when lightning is slim and taking it down when storm season arrives. My next idea was to get a wilson 5000 and put it up on a push pole outside the attic window and extend it above the roof and put it up when ever I needed, Is this a good idea, and will the performance be the same as if I were running the Imax 2000? Thanks for any information!
How in the heck did they do it back in the day with just strapping it to the chimney and calling it good?
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Sandbagger
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Post by Sandbagger on Jul 14, 2015 21:26:28 GMT -5
I been wanting to put up a base antenna now for awhile, I will admit that Iam afraid of lightning! Who isnt? Last fall I bought a new Imax 2000 and put the base at 20' off the ground, attached to 2 pieces of 10'Pipe strapped to my porch post. I took it down in april when the storm season started. It worked great swr was flat and I talked all over that winter. My goal was to put up my 40' tower I have had in the shed now for 4 yrs, and fly the Imax on top of that!! That thing would rock right? But the question is that now matter how good of a ground and arresters you have you are still vaurnable to a strike, correct? I was going to ground each leg of the tower to a 8' ground rod. will this be enough, along with a lightning arrester? I would like to have this station up all the time instead of putting it up in the fall when lightning is slim and taking it down when storm season arrives. My next idea was to get a wilson 5000 and put it up on a push pole outside the attic window and extend it above the roof and put it up when ever I needed, Is this a good idea, and will the performance be the same as if I were running the Imax 2000? Thanks for any information! How in the heck did they do it back in the day with just strapping it to the chimney and calling it good? Lightning strikes are always a concern, but to give you a little perspective, I've had a sizable outside CB antenna of some type now for 41 years. Everything from ground planes on 20' of mast, to beams on a 45' tower. And I have NEVER been hit by lightning. I used to unplug my coax every night, and when I went out, to prevent a direct strike from zapping the radio. Lately, I don't bother anymore, since there are trees nearby that are much higher than my antenna. Your risk of a lightning strike depends on where you are. If your antenna is the highest point in the surrounding area, then chances are good that you'll be hit. Conversely, if you're in a hole surrounded by taller trees and buildings, the likelihood of a strike is reduced (but never eliminated). Grounding is a double edged sword. On the one hand, by tying your antenna to the same electrical potential as the ground, you will present a greater attraction to lighting. On the other hand, if you're solidly grounded and you are hit, most of the energy will go directly to ground, and not seeking a convoluted alternate path through your feedline, equipment, other appliances, and the metal pipes and wiring in your house. Fiberglass antennas don't handle lightning well. Most will shatter into a million shards, from the heat of the lightning. The old metal monsters of the 70's fared far better in that regard. Bottom line: Don't let fear of lightning ruin your fun. That's why we have homeowner's insurance.......
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Post by cbrown on Jul 15, 2015 8:23:25 GMT -5
I agree with Sandbagger, although I did get hit once many many years ago. But nothing since then and I live in an area when there is a lot of iron in the rock & soil. I do have this inline now, too. www.iceradioproducts.com/impulse1.html
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roadrunner
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Post by roadrunner on Jul 15, 2015 9:03:40 GMT -5
Correct me if I am wrong but as far as i know lighting starts from the ground and moves up word. Roadrunner
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Sandbagger
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Post by Sandbagger on Jul 15, 2015 13:41:28 GMT -5
Correct me if I am wrong but as far as i know lighting starts from the ground and moves up word. Roadrunner In the grande schem of things, does it really matter? Actually what happens is that there is a "feeder" bolt that originates from the ground upward, and the lightning discharge from the clouds links up to it and travels back down.
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Post by BBB on Jul 15, 2015 15:55:46 GMT -5
Last night we had a very close strike, you know one of those flash-bangs. I didn't worry about it because I always disconnect the coax if storms are imminent or I'm leaving the house for an extended time in the summer months. Just a good habit to get into although I'm sure there are times I forget.
I'm of the "if it doesn't look like a ground, it isn't" club due to lack of funding. That means I mounted my Sirio 2016 aluminum vertical antenna on a non- conductive 1-1/4" fiberglass pole off the metal capped chimney. That non-conductive mast combined with disconnecting the coax should be a close to an infinite resistance circuit path for any lightning feeders. Also the trees around me are higher than the top of the antenna by a good 20' or so.
There is a lot of information about proper grounding of antennas and I believe the consensus is that the more grounding, the better. But it better be extra heavy duty stuff if your asking that grounding system to actually handle and deflect a direct strike without vaporizing. That translates into a whole bunch of money needed to purchase the proper suppressors, heavy gauge braided cooper cable, copper strapping, and related bronze bonding hardware.
If I had the money, I'd have the station bonded to broadcast and cell tower specs. I've seen several of these applications and the size of the CU stuff they use would astound you.
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roadrunner
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Post by roadrunner on Jul 16, 2015 18:19:50 GMT -5
I feel that Sandbager is correct by saying that in the grand picture of this (it won't matter). Even if your house or antenna does not get hit you could sill have major damage to alot of other things in your house. Throw the coax out the window before this happens. Roadrunner
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Post by MonkeyMan on Jul 17, 2015 7:25:57 GMT -5
Bottom line: Don't let fear of lightning ruin your fun. That's why we have homeowner's insurance....... Exactly. And who doesn't like buying new equipment?
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roadrunner
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Post by roadrunner on Jul 18, 2015 7:40:08 GMT -5
For me in the world of grounding wire there is only one choice and it's not the wire mesh type. The only thing i use is welding cable but it can get very expensive if your using alot of it. Roadrunner
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Post by whitetail on Jul 21, 2015 6:09:40 GMT -5
Thanks for all the replies guys. Beings that the tower is going to be maybe 80' from the house I was going to have a connection at the bottom of the tower to disconnect the coax. Someone mentioned about height of other trees. I know I will be very close to the same level of some of the tree tops with this tower. overall height will be around 70' to the top of the antenna. I have several pine trees going around my property kinda like an L shape going aroung the property line. Is it a good Idea to put it anywhere near these trees perferably where the property makes the 90* turn? Just getting some ideas here, I dont want to dig a hole and concrete it and get it all set up and then cant get the swr to tune. Do you think the trees will have an inpact on swr? I know we are all never eliminated from possibly taking a hit. I have a few ideas for grounding and using heavy heavy solid copper wire at the base of the tower and making a grid of several ground rods. also running a short pieces of wire from section to section where pieces of tower join together, doing this on each connection point for more grounding safety. What do you all think? I got to get this thing up!
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Post by roadrunner on Jul 22, 2015 8:56:14 GMT -5
Hi there Whitetail, I just wanted you to know a few things about your tower and the length of the LMR- 400 coax cable. You said that the tower is going to be some 80 feet away from the house and the height of the tower is going to be around 70 feet. That long run of 150 feet coax cable is going to cause some loss to your transmitting power. I did some figuring on how much your going to lose at the numbers you posted. Using LMR-400 at 150 feet the (cable Run Attenuation) is going to be 2.3 db.
The total cable assembly loss are around 2.5 db. If you can cut down the length of coax you will get less loss.
As far as the trees go, they do in fact cause interference. (High SWR readings) There are a number of ways around this problem. Getting above the tree line, cutting the trees back in some cases but using a tuner to find tune the SWR would help.
Your not the only one that has this problem. I have the same thing going on here with all the trees but the antenna I need to put up is a big beam that needs to be at least 70 feet in height. I have been working on a project to solve alot of these kinds of problems with towers but don't want to say anymore about it yet.
Here is another thing you should think about, there are regulations for putting towers up with out a permit from the city. Better check first with the city! Roadrunner
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Post by Sandbagger on Jul 22, 2015 9:23:04 GMT -5
Hi there Whitetail, I just wanted you to know a few things about your tower and the length of the LMR- 400 coax cable. You said that the tower is going to be some 80 feet away from the house and the height of the tower is going to be around 70 feet. That long run of 150 feet coax cable is going to cause some loss to your transmitting power. I did some figuring on how much your going to lose at the numbers you posted. Using LMR-400 at 150 feet the (cable Run Attenuation) is going to be 2.3 db. The total cable assembly loss are around 2.5 db. If you can cut down the length of coax you will get less loss. As far as the trees go, they do in fact cause interference. (High SWR readings) There are a number of ways around this problem. Getting above the tree line, cutting the trees back in some cases but using a tuner to find tune the SWR would help. Your not the only one that has this problem. I have the same thing going on here with all the trees but the antenna I need to put up is a big beam that needs to be at least 70 feet in height. I have been working on a project to solve alot of these kinds of problems with towers but don't want to say anymore about it yet. Here is another thing you should think about, there are regulations for putting towers up with out a permit from the city. Better check first with the city! Roadrunner That's not correct. 150' LMR-400 has less than 1db of loss at 27 mhz. So it's not all that bad. Here's a handy loss calculator to figure out system losses at various power and SWR levels, frequencies, with different lengths and types of cable: www.arrg.us/pages/Loss-Calc.htm
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Post by BBB on Jul 22, 2015 10:49:13 GMT -5
Try not to use coax barrel connectors in your final run from the tower to the shack electronics. They create some signal loss and if not water proofed properly, may cause SWR problems. They're not so bad on 27 MHz, but signal losses are much greater at higher frequencies. I'm sure we've all used them at some point though I like this guys take on lightning protection: always disconnect the antenna coax feed in the shack when not in use, then connect it to a short coax length going outside hanging in free air. That's what I've been doing for years now without incident. www.k3dav.com/antlightningprotectors.htm
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Post by roadrunner on Jul 22, 2015 17:45:55 GMT -5
Sandbager, The coax i calculated was ultra flex LMR coax because we were talking about a radius bend of 4 inch's as a choke. Your right about the LMR 400 being less loss than what i posted but i felt that between the length of the coax and the connectors the db loss would be at lest one. I rechecked the calculated db loss with LMR 400 and it was .948 at 27 meters. Sorry, But the point i was trying to communicate to Whitetail was to shorten the coax as much as he could. (That's it). Every 1 db of loss in the system represents a full 20 % lost of power. LMR coax cable has 6.6 db per 100 feet of loss not ultra flex. I would like to say Just one more thing, every element of you system has to be accounted for.Coax runs lighting protectors ETC all have to be added up to get the full view of the over all loss. Roadrunner
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Post by cbrown on Jul 23, 2015 8:38:05 GMT -5
LMR-400 Ultra Flex with a running length of 150 feet has a total cable assembly loss of 1.3 dB at 27 MHz.
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Sandbagger
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Post by Sandbagger on Jul 23, 2015 22:03:03 GMT -5
Sandbager, The coax i calculated was ultra flex LMR coax because we were talking about a radius bend of 4 inch's as a choke. Your right about the LMR 400 being less loss than what i posted but i felt that between the length of the coax and the connectors the db loss would be at lest one. I rechecked the calculated db loss with LMR 400 and it was .948 at 27 meters. Sorry, But the point i was trying to communicate to Whitetail was to shorten the coax as much as he could. (That's it). Every 1 db of loss in the system represents a full 20 % lost of power. LMR coax cable has 6.6 db per 100 feet of loss not ultra flex. I would like to say Just one more thing, every element of you system has to be accounted for.Coax runs lighting protectors ETC all have to be added up to get the full view of the over all loss. Roadrunner The link I provided is a really nice loss calculator which you can use to compare various common coax cable types, at various frequencies and lengths, and also factor in SWR losses. It's a great way to decide which feedline type you should buy for your setup. I agree that the shortest feedline length possible should be considered for minimum loss. But sometimes, other factors may play a more important role. For instance, if placing the tower farther away from your house minimizes RFI, or it places the antenna in a less obstructed area, then it's probably worth the extra 1 db of feedline loss. When deciding antenna placement, it's best to consider all the pro's and con's.
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Post by cbrown on Jul 24, 2015 8:28:16 GMT -5
And if you are doing a longer run, there are feedline choices that will reduce your loss.
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Post by whitetail on Jul 26, 2015 6:36:07 GMT -5
Thanks guys, I didnt know it would be that much loss with the length of coax. As much as I would like to keep the tower as far away from the house as possible I guess I am going to have to move it closer and maybe at least cut the loss in half if not more. I kinda figured the trees will inter fear with the swr/ signal. Iam glad Iam asking these questions now instead of finding out the problems when all the hard work is done and the tower is up. I wont have to worry about the city as roadrunner said, Iam out and away!! I saw an rf choke on another thread, how many loops should be made, and this is done just beneath the feedpoint on the bottom of the antenna right?
Sandbagger: Did you do anything special at the bottom of your tower? Ground rods in the middle of the concrete, or out and away from the base? How deep?
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roadrunner
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Post by roadrunner on Jul 26, 2015 9:29:27 GMT -5
Whitetail, I was wounding if a friend or someone gave you that 70 foot tower you have? The reason why i ask is that towers are very expensive and hold good size antennas or beams. If it was me i would shop around for a good aluminum antenna to put on top of that tower. Don't get me wrong the I Max works good but there are some aluminum antennas out there that don't cost alot of money that work better. The best thing your doing is getting that antenna up 70 feet so why not put a better antenna on it. (Just food for though) Roadrunner
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Post by cbrown on Jul 27, 2015 8:41:08 GMT -5
I saw an rf choke on another thread, how many loops should be made, and this is done just beneath the feedpoint on the bottom of the antenna right? It's not the number of coils that matter, it's more the length of coax coiled. For CB/11M, you'd need about 5-6 foot of coax coiled.
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Post by whitetail on Jul 28, 2015 5:30:15 GMT -5
Whitetail, I was wounding if a friend or someone gave you that 70 foot tower you have? The reason why i ask is that towers are very expensive and hold good size antennas or beams. If it was me i would shop around for a good aluminum antenna to put on top of that tower. Don't get me wrong the I Max works good but there are some aluminum antennas out there that don't cost alot of money that work better. The best thing your doing is getting that antenna up 70 feet so why not put a better antenna on it. (Just food for though) Roadrunner Roadrunner- Around where Iam at there are old camps and houses that have towers still up, back in the day used for TV antenna mounting structure. People put ads in the classifieds- such as make offer, come and take down. There are so many still standing around not even being used, its ashame they are going to waste just sitting there! I got mine from an add I saw, the guy wanted $120 bucks for a 40'. Long story short I drove 45 mins and he already had it down and ready for me. He just bought this place and was going to use it as rental house and didnt need this tower . ( the tower is 40' 70' was going to be my overall height) I saw an rf choke on another thread, how many loops should be made, and this is done just beneath the feedpoint on the bottom of the antenna right? It's not the number of coils that matter, it's more the length of coax coiled. For CB/11M, you'd need about 5-6 foot of coax coiled. Cbrown, Thanks for the information,
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Sandbagger
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Post by Sandbagger on Jul 28, 2015 21:18:33 GMT -5
Thanks guys, I didnt know it would be that much loss with the length of coax. As much as I would like to keep the tower as far away from the house as possible I guess I am going to have to move it closer and maybe at least cut the loss in half if not more. I kinda figured the trees will inter fear with the swr/ signal. Iam glad Iam asking these questions now instead of finding out the problems when all the hard work is done and the tower is up. I wont have to worry about the city as roadrunner said, Iam out and away!! I saw an rf choke on another thread, how many loops should be made, and this is done just beneath the feedpoint on the bottom of the antenna right? Sandbagger: Did you do anything special at the bottom of your tower? Ground rods in the middle of the concrete, or out and away from the base? How deep? I would mount your tower in the place where it puts the antenna in the clear, away from trees and other objects that could cause reflections, or otherwise distort your signal pattern. I wouldn't worry about cable loss at 150' if you are using LMR-400. If you were using RG-58, on the other hand, then I'd worry . I ran a single 8' copper clad ground rod when I had my tower. It's all you really need for DC ground.
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Post by whitetail on Feb 29, 2016 17:20:19 GMT -5
Well, the tower project is going to start this spring. I been looking over my drawings and thinking of how things are going to work. Now Iam wondering how Iam going to get this tower up! I watched several you tube videos and some clowns tried to put a 30ft tower up by walking it up and failed, what a big mess that was. I found a video that was the best but didnt figure this in my plan. Idea Was putting a seperate pipe up beside the tower with a pulley near the top. A winch would be mounted towards the bottom of the pipe with the cable running up along the pipe and through the pulley at the top which would attach to the tower. Now, say I have a 20 ft pole, that means I would have to attach the winch cable 20' from the bottom of the tower right? So when the winch is pulling the tower up and it gets in vertical position the cable should be even with the top of the pipe. Iam thinking if I attach the hook to the tower any higher then the pole there would be down force pulling on the tower and it may bend the cross bars that it is hooked to. What do you guys think? I would like to have way that I can bring this thing down to make adjustments when ever I need to. I guess this is something that was overlooked.
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Sandbagger
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Post by Sandbagger on Mar 1, 2016 7:10:08 GMT -5
Well, the tower project is going to start this spring. I been looking over my drawings and thinking of how things are going to work. Now Iam wondering how Iam going to get this tower up! I watched several you tube videos and some clowns tried to put a 30ft tower up by walking it up and failed, what a big mess that was. I found a video that was the best but didnt figure this in my plan. Idea Was putting a seperate pipe up beside the tower with a pulley near the top. A winch would be mounted towards the bottom of the pipe with the cable running up along the pipe and through the pulley at the top which would attach to the tower. Now, say I have a 20 ft pole, that means I would have to attach the winch cable 20' from the bottom of the tower right? So when the winch is pulling the tower up and it gets in vertical position the cable should be even with the top of the pipe. Iam thinking if I attach the hook to the tower any higher then the pole there would be down force pulling on the tower and it may bend the cross bars that it is hooked to. What do you guys think? I would like to have way that I can bring this thing down to make adjustments when ever I need to. I guess this is something that was overlooked. If you do something like that, you'd better make sure that the "pipe" is at least as strong as the tower or when you start pulling up on it, it will bend. That happened to a friend of mine who had a similar idea. We used to pull up a fixed 40' tower with a hinged base. We simply walked it up to about a 30 degree angle, then we were able to pull it up the rest of the way with a small farm tractor with a line attached near the top of the tower. Someone would then have to climb the tower to detach the line, but that was no big deal.
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Post by whitetail on Mar 1, 2016 9:53:18 GMT -5
Well, the tower project is going to start this spring. I been looking over my drawings and thinking of how things are going to work. Now Iam wondering how Iam going to get this tower up! I watched several you tube videos and some clowns tried to put a 30ft tower up by walking it up and failed, what a big mess that was. I found a video that was the best but didnt figure this in my plan. Idea Was putting a seperate pipe up beside the tower with a pulley near the top. A winch would be mounted towards the bottom of the pipe with the cable running up along the pipe and through the pulley at the top which would attach to the tower. Now, say I have a 20 ft pole, that means I would have to attach the winch cable 20' from the bottom of the tower right? So when the winch is pulling the tower up and it gets in vertical position the cable should be even with the top of the pipe. Iam thinking if I attach the hook to the tower any higher then the pole there would be down force pulling on the tower and it may bend the cross bars that it is hooked to. What do you guys think? I would like to have way that I can bring this thing down to make adjustments when ever I need to. I guess this is something that was overlooked. If you do something like that, you'd better make sure that the "pipe" is at least as strong as the tower or when you start pulling up on it, it will bend. That happened to a friend of mine who had a similar idea. We used to pull up a fixed 40' tower with a hinged base. We simply walked it up to about a 30 degree angle, then we were able to pull it up the rest of the way with a small farm tractor with a line attached near the top of the tower. Someone would then have to climb the tower to detach the line, but that was no big deal. Thats what I was wondering if someone would bring up, the strength of the pipe. Yes I agree, the higher up the pipe you go the more of a chance it has to bend when pulling up or down. Mine also has a hinged base. (tilt over) I was going to have a 6' support post somewhere around the 30' -35' mark so the tower can rest on that when it is down, so it isnt directly laying on the ground to make adjustments, and it may be easier to start raising up. Do you think an ATV would be able to pull this thing up, and lay it down with out a problem?
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Post by whitetail on Mar 1, 2016 9:59:25 GMT -5
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Sandbagger
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Post by Sandbagger on Mar 1, 2016 10:37:26 GMT -5
This guy did it right. See the support rail welded to the pipe along with the guy lines to keep it from bending. If you take the time to do it like that, chances are it will probably work, as long as you aren't lifting 80' towers with HF tri-band beams on them. I would not try lifting a tower with an ATV. Most are not heavy enough, and you run the risk of losing control when the tower is at its heaviest point (~35-45 degrees) on the way up. A pickup truck would do it though......
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Post by whitetail on Mar 1, 2016 11:29:09 GMT -5
This guy did it right. See the support rail welded to the pipe along with the guy lines to keep it from bending. If you take the time to do it like that, chances are it will probably work, as long as you aren't lifting 80' towers with HF tri-band beams on them. I would not try lifting a tower with an ATV. Most are not heavy enough, and you run the risk of losing control when the tower is at its heaviest point (~35-45 degrees) on the way up. A pickup truck would do it though...... Yes I see the support pipe welded to the pipe. You are talking about the one that goes back towards the roof right? 1:59 & 2:01, its a really quick shot of it. I also see the the rail running upward beside the pipe, this is the support rail? It doesnt look like much but hey it worked, also like you mentioned the guy lines for added support. I like the guy wire Idea. Dont plan on raising up 80' towers. My setup should get me plenty high enough for what I need. I have a buddy that can get me some heavy natural gas pipe.
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Post by 2600 on Mar 2, 2016 1:07:29 GMT -5
Never forget that a lightning stroke is really just an insanely intense but brief burst of wide-band RF energy. Literally "DC to light", all the way up to X-ray wavelength.
The tiny slice of the electromagnetic spectrum that your antenna is built to suck in out of the air can still soak up hundreds of Watts of RF power or more. Depends on the distance. Sure it's brief, but it's large. The neighbor's tree across the street may protect your antenna, but if the beam is pointed that way, your receiver's input circuits may suffer. We have seen more than a few Browning receivers with the winding darkened or burned on the antenna coil. A solid-state receiver is usually not so robust.
Pulling the coax plug is the only surge protector that works. Well, pulling the power cord, too. Lightning damages more radios through the power cord than the antenna socket, in my experience. Plugging the whole station into a 5-buck WallyWorld outlet strip simplifies pulling the plug on the whole station at once.
73
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Post by whitetail on Mar 2, 2016 20:49:06 GMT -5
Doing some reading and learning things. But are they the truth? I hear the rule of thumb for a base antenna is the base should be set at 36' off the ground? If I go higher a groundplane kit is in need for the antenna to work properly, ?? Talking about an Imax 2000. My setup when said and done the base will be around 45'-50' up the tower, then the rest of the antenna from that point. Will I need a groundplane kit for this? Also I hear that higher isnt always better, which i think is a lie. because in a mobile when you are driving and dip into a hole you are pretty much dead, but going up the other side of the mountain and once on top it is clear and the signal is strong again. So thats why I think high is better. Please tell me if this is the same for a base antenna being high. Thanks
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