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Post by whitetail on Apr 15, 2016 4:18:24 GMT -5
Well I am breaking ground tomorrow for the tower! Some last minute thoughts. Iam just wondering if I should go bigger on the foundation. The base plate of the tower is 15"x15" square, I was going to make it 30"x30" inches square. If I place the base plate right in the center of the 30x30 that gives me aprox 7" of foundation sticking out of all sides of the bottom plate. I feel that this is maybe not enough. Maybe I should go 36x36 square and 4 1/2' deep. If I go 36" square that will give me aprox 10" of foundation sticking out of all sides of the bottom plate. Will this be enough to support the tower? I Just want to do it right the 1st time, overkill is better then not enough. The bottom of the hole will have rods driven in at least 3' below that and sticking up so the cage can be attached. What are your thoughts?? I am getting 3 more sections of tower from a camp owner that no longer needs it, I may want to put all this up someday, so thinking ahead to compensate for that in the future! Tower 40' high with Imax 2000 or a 500. Well it all depends on whether the tower is free standing, attached to another structure, or guyed. If free standing, I'd go 4'X 4' X 4'. If attached to another structure or guyed, you could get away with 3 X 3 X 3. Also, you have to consider what you might want to put on there in the future. A simple IMax antenna is only marginally more wind resistance than the tower itself. But if someday, you decide you want a 5 element beam up there, the wind resistance is going to get ugly if the tower isn't supported well enough. The tower is going to be free standing, it is going to be out in the open yard. Yes we have to think about the future and I may as well do the foundation bigger and stronger now in stead of doing it later. 4x4x4 sounds good that will help if I want to put more sections on in the future also.
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Sandbagger
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Post by Sandbagger on Apr 15, 2016 6:00:00 GMT -5
Well it all depends on whether the tower is free standing, attached to another structure, or guyed. If free standing, I'd go 4'X 4' X 4'. If attached to another structure or guyed, you could get away with 3 X 3 X 3. Also, you have to consider what you might want to put on there in the future. A simple IMax antenna is only marginally more wind resistance than the tower itself. But if someday, you decide you want a 5 element beam up there, the wind resistance is going to get ugly if the tower isn't supported well enough. The tower is going to be free standing, it is going to be out in the open yard. Yes we have to think about the future and I may as well do the foundation bigger and stronger now in stead of doing it later. 4x4x4 sounds good that will help if I want to put more sections on in the future also. And you always have the option of attaching guy lines to it if/when you put up a larger antenna.
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Post by thehobo on Apr 15, 2016 9:49:00 GMT -5
i mite be alittle old fashion, but anything over 40 feet tall i at least put guy wires at the top section of the tower.. in my mind it takes a load off of me woorring about it.. have done this since 1958 when i first started this cb thing.. but there agin most of the towers had big beams on them.. so agin look at what mite you use in the future and will the tower suport it?? my 5 cents worth
thehobo
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Post by whitetail on Apr 17, 2016 20:13:30 GMT -5
The ground breaking went good, my friend came over with his tractor with a post hole auger on the back, we drilled several holes in the square area, it really loosened up the dirt. I spent spent yesterday evening and today evening in the hole cleaning out and squaring up the sides and making everything straight. Tell ya what we got down into some hard clay at the 36" mark and that stuff is tough, you can see the different layers of soil and its hard. I ended up going 48" deep and 40X40 square. I got one heck of a hole here, I went a bit bigger then what sandbagger said so I should be in good shape. Iam getting rebar tomorrow and going to get my cage installed in the grave. My buddy is going to weld everything together instead of wire tieing together. I made a triangular cage, the shape of the tower, off of each point (3 points) I am Going to weld 3/4" threads to the cage and these will stick up through the concrete, my base plate of the tower has 3 holes drilled through it, The base plate will slide over the threads and rest on top of the pad. Is 3/4" thick enough? Now the question - how much thread should I leave sticking up past the top of the pad? Is it good to have alot sticking out or just a few inches? I may try to pour on saturday, if I get done. here is something simular to get an idea of what Iam doing, (the foundation pictures). my triangular cage bolts are very simular to his. Is this enough to have stick out? My cage is made out of all rebar, no flat bar. wf0gm.fpage.com/tower3.htm
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Sandbagger
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Post by Sandbagger on Apr 18, 2016 6:23:11 GMT -5
The ground breaking went good, my friend came over with his tractor with a post hole auger on the back, we drilled several holes in the square area, it really loosened up the dirt. I spent spent yesterday evening and today evening in the hole cleaning out and squaring up the sides and making everything straight. Tell ya what we got down into some hard clay at the 36" mark and that stuff is tough, you can see the different layers of soil and its hard. I ended up going 48" deep and 40X40 square. I got one heck of a hole here, I went a bit bigger then what sandbagger said so I should be in good shape. Iam getting rebar tomorrow and going to get my cage installed in the grave. My buddy is going to weld everything together instead of wire tieing together. I made a triangular cage, the shape of the tower, off of each point (3 points) I am Going to weld 3/4" threads to the cage and these will stick up through the concrete, my base plate of the tower has 3 holes drilled through it, The base plate will slide over the threads and rest on top of the pad. Is 3/4" thick enough? Now the question - how much thread should I leave sticking up past the top of the pad? Is it good to have alot sticking out or just a few inches? I may try to pour on saturday, if I get done. here is something simular to get an idea of what Iam doing, (the foundation pictures). my triangular cage bolts are very simular to his. Is this enough to have stick out? My cage is made out of all rebar, no flat bar. wf0gm.fpage.com/tower3.htmSounds like you've covered your bases well. as for how much thread to leave out, in cases like this it's better to have too much than not enough. You can always hacksaw off the excess after the base is installed. But if you don't have enough, you're basically screwed (no pun intended). Be careful when you pour the concrete, so as not to shift or otherwise disturb your rebar cage and the base mount. It needs to remain level.
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Post by BBB on Apr 18, 2016 9:00:27 GMT -5
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Post by cbrown on Apr 18, 2016 10:21:56 GMT -5
Iam getting rebar tomorrow and going to get my cage installed in the grave. My buddy is going to weld everything together instead of wire tieing together. Unless the rebar is an ASTM A706 grade, you can not weld it, the carbon is too high. I'd suggest just tying it together with wire.
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Post by whitetail on Apr 18, 2016 14:20:27 GMT -5
Thanks for the replies and the sites to look at. I was told the following today- Steel is stubbed above the concrete and all the rest of the steel is inside the concrete. there are no rods penetrating the earth below the concrete, so no path for lightning goes through the concrete. What do you make of this? Can I still put rods in the ground below the concrete but not attach them to the triangular cage? Kinda to hold the base in place for insurance! Here are some some pictures, these will give you guys an idea of what Iam up to. Attachment DeletedAttachment DeletedAttachment Deleted
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Post by cbrown on Apr 19, 2016 9:29:13 GMT -5
You welded straight pieces of all thread to the rebar. The possibility of weld failure is very high for the all thread rod to break the weld. Since you didn't use bent anchor bolts (also called L bolts), the all thread will pull out of the concrete very easily.
My suggestion: Remove the straight all thread and use 3 bent anchor bolts wire tied with a minimum 6" embeded into the concrete.
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Post by cbrown on Apr 19, 2016 9:32:51 GMT -5
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Sandbagger
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Post by Sandbagger on Apr 19, 2016 10:06:15 GMT -5
You welded straight pieces of all thread to the rebar. The possibility of weld failure is very high for the all thread rod to break the weld. Since you didn't use bent anchor bolts (also called L bolts), the all thread will pull out of the concrete very easily. My suggestion: Remove the straight all thread and use 3 bent anchor bolts wire tied with a minimum 6" embeded into the concrete. I agree. I used L-Bolts with mine and they worked well, and never worked loose.
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Post by BBB on Apr 19, 2016 19:37:11 GMT -5
Yes, if not J bolts then some all thread with some 90s bent on the bottom.
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Post by thehobo on Aug 23, 2016 12:41:41 GMT -5
well after a few months i finally got my mr coily up to 25 feet so that i could check all of whats going on.. with a 3 watt radio swinging to 15 the needle dont even move on the bird.. put a 1k dk into it and it just nudged the needle off of the peg.. makes me one happy cber!! even at about 80 years old im still thriller when things come out as expected.. now that its ok ill put it up higher later on.. let me say its a tall antenna and such workmanship i think it needed to be well built.. this thing is one nice unit.. so im kicking up my heels somewhat, ye hoo.. lol..
thehobo
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Post by whitetail on Aug 23, 2016 14:58:41 GMT -5
I had my triangular cage redone with (3) L angles attached to the side of the cage, These measure 20" from the top of the threads to the bottom where it bends 6" at the 90* bend. (there are 3 of these ) The triangular cage measures 2' long and will hang down in the center of my hole which is 44" x 44" x 48" deep. Now in the 4 corners of the hole I have rebar pounded 2' into the ground with 32" sticking up, I then took rebar and wire tied a piece to all 4 sides, the rebar was placed 18" up the vertical bars. Now Iam wondering if this will be ok, due to a post that said ( Steel is stubbed above the concrete and all the rest of the steel is inside the concrete. In other words, there are no rods penetrating the earth below the concrete, so no path for lightning goes through the concrete.)
in other words my triangular cage is going to sit 20" centeralized surrounded by concrete.
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Post by cbrown on Aug 25, 2016 13:08:59 GMT -5
You could install a separate copper ground rod next to the tower, but current electric code requires you to ground the entire electrical system together so there is no difference in the ground potential.
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Post by whitetail on Oct 13, 2016 19:53:18 GMT -5
Well alot has been done since the last time I been on here long enough to look around. My tower is ready to go up this weekend, alot of work has gone into this project and endless hours of wire wheeling, priming, & painting. I will have pictures of the process & video of the 1st tower raising posted hopefully in a few weeks when the tower is up and I can finally sit in my recliner and relax! What a busy summer its been. I do have a question though, at the top of the tower on the last section how it comes to a point so you can stick a pipe in so you can attach the antenna to. Question= the piece of pipe that I slide down in there should I paint that or do I want that bare metal to metal? I have the piece all sanded down to bare metal, but thought about before I ran primer and paint on it. Also Where the Imax is going to connect to that same piece of pipe should all that portion of the pipe be left bare( where the u clamps go around and where the pipe goes against the Imax's connection plate? I thought maybe this may help with grounding. Please let me know what you all think! Ok here is a pic.
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Post by BBB on Oct 14, 2016 18:29:52 GMT -5
You can leave the metal bare where the mast pipe is bolted or clamped to the tower but it will need an anti-corrosive coating or treatment in those areas. Or you could bolt a suitable sized HD ground wire connecting the tower to the mast pipe. The latter would have a smaller surface area to have to maintain the proper metal to metal bonding that is required. "NO-OX-ID A-SPECIAL" works: www.finishing.com/135/13517extNoOxId.pdf
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Post by whitetail on Oct 15, 2016 20:20:29 GMT -5
Thank you BBB. that NO-OX-ID A-SPECIAL I never herd of, but from what I read it is really good stuff, and you even said yourself, will be getting some of that for sure. Thanks for the info for the top section, Iam this far along in the project no sense in taking any short cuts now!
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Post by whitetail on Oct 15, 2016 20:36:44 GMT -5
Well a little more progress on the tower today, I had one heck of a time getting the sections together. It took 2 of us to get them together. I even wire brushed the inside of the pipes, Still a tight fit going on. I suggested we use some grease in there, we coated the inside of the pipes along with the pointed ends and with a little effort and wiggle side to side a bit they slid on. Are these supposed to be a very snug fit? I never had this tower together so I dont know. We put 3 sections on and as ancious as Iam I said lets try to stand it up by hand, well it pivoted up really nice with 2 of us walking it up, no problem. Put the tilt pin in and stepped back and admired. Small issue is that it wiggles a small bit side to side with 3 sections on, thats not with the imax on top yet either. Iam a bit concerned, should I put the 4th section on? What about guy wires? I really didnt want wires but I want it to be safe and dont want any issues at 20* below 0 or at any time that is. How would I guy a triangular 3 legged tower? I have a winch that I need to get on my pole as well, Iam probably going to need it if and when I put the 4 section on and the antenna. It is supposed to be a free standing tower.
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Post by whitetail on Oct 17, 2016 20:03:45 GMT -5
Well the tower is up, I decided to put the 4th section on, total height is right around 69'. (to the tip of the Imax.) Doing some testing and notice some strange things happening, The readings from my meter are different from early spring, when I took my temp station down. My wattage is showing less, swr is reading a 1.2 on ch 40, & 1.3 on ch 1. which Is not really bad foe swr right? Now when I key down the tap light comes on in the other room on the other end of the house, what is causing this? Too much rf energy coming back down the coax? Can rf reflection weaken your signal as well? I didnt make a rf choke at the feed point of the antenna, as it was something I overlooked, do you think by making a rf choke at the feedpoint improve any of my issues? I red somewhere also The RF choke creates an electromagnetic field on the chokes surface, and within the donut hole. This field attracts the stray RF and chokes it off before it travels down the coax, and it is dissipated within the EM field. Hence the term "Choke". In some ways, it almost acts like a ground radial and reflects slightly the RF radiated from the antenna, to a more upwards angle sending more of the signal towards the horizon where it belongs, and not in your radio room. what do you guys think?
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Sandbagger
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Post by Sandbagger on Oct 17, 2016 20:25:43 GMT -5
Well the tower is up, I decided to put the 4th section on, total height is right around 69'. (to the tip of the Imax.) Doing some testing and notice some strange things happening, The readings from my meter are different from early spring, when I took my temp station down. My wattage is showing less, swr is reading a 1.2 on ch 40, & 1.3 on ch 1. which Is not really bad foe swr right? Now when I key down the tap light comes on in the other room on the other end of the house, what is causing this? Too much rf energy coming back down the coax? Can rf reflection weaken your signal as well? I didnt make a rf choke at the feed point of the antenna, as it was something I overlooked, do you think by making a rf choke at the feedpoint improve any of my issues? I red somewhere also The RF choke creates an electromagnetic field on the chokes surface, and within the donut hole. This field attracts the stray RF and chokes it off before it travels down the coax, and it is dissipated within the EM field. Hence the term "Choke". In some ways, it almost acts like a ground radial and reflects slightly the RF radiated from the antenna, to a more upwards angle sending more of the signal towards the horizon where it belongs, and not in your radio room. what do you guys think? This is one of the big disadvantages of the radial-less "stick" style antenna design. A ground plane vertical needs those radials to decouple RF. Without that counterpoise, it tends to use the shield of the coax as the counterpoise, and RF currents run down the shield and will couple into your shack and nearby homes. The coax choke should reduce this significantly. But it has to be mounted right at the feedpoint to be most effective. Another alternative would be to add the radial kit for the Imax, which should help to decouple those RF currents as they should be. Or do both. As for the differences in your wattage readings, since you raised your antenna, I assume you changed the length of coax. What that does is change the RF voltage peaks which occur roughly at every 1/2 wave. This will change what the wattmeter indicates, but not necessarily the true power. The only time a wattmeter is truly accurate, is when it is terminated into a purely resistive 50 ohm dummy load. The best you can do, is to measure your power with an accurate meter (like a Bird 43), into the dummy load. Then switch over to your antenna setup and wattmeter, and adjust it to agree with the reading you got on the calibrated dummy load setup. That's about as good as it gets, as far as accuracy goes.
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Sandbagger
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Post by Sandbagger on Oct 17, 2016 20:32:48 GMT -5
Well a little more progress on the tower today, I had one heck of a time getting the sections together. It took 2 of us to get them together. I even wire brushed the inside of the pipes, Still a tight fit going on. I suggested we use some grease in there, we coated the inside of the pipes along with the pointed ends and with a little effort and wiggle side to side a bit they slid on. Are these supposed to be a very snug fit? I never had this tower together so I dont know. We put 3 sections on and as ancious as Iam I said lets try to stand it up by hand, well it pivoted up really nice with 2 of us walking it up, no problem. Put the tilt pin in and stepped back and admired. Small issue is that it wiggles a small bit side to side with 3 sections on, thats not with the imax on top yet either. Iam a bit concerned, should I put the 4th section on? What about guy wires? I really didnt want wires but I want it to be safe and dont want any issues at 20* below 0 or at any time that is. How would I guy a triangular 3 legged tower? I have a winch that I need to get on my pole as well, Iam probably going to need it if and when I put the 4 section on and the antenna. It is supposed to be a free standing tower. Yes, the sections should be snug, otherwise they will "wiggle" back and forth when the wind blows. I forget whether your tower is rated as free standing, or whether it requires guy lines. 40 feet of unsupported tower is a bit much if it's not rated to be free standing. On the other hand, a single Imax is not a lot of wind loading. But if it looks like it wants to sway when the wind blows, I'd attach guy lines to it as close to the top as you can get. 3 of them (one on each leg) should do the trick. And since you're not running a beam, you don't have to worry about breaking up the wire or using non-metallic lines.
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Post by whitetail on Oct 18, 2016 14:30:08 GMT -5
Well the tower is up, I decided to put the 4th section on, total height is right around 69'. (to the tip of the Imax.) Doing some testing and notice some strange things happening, The readings from my meter are different from early spring, when I took my temp station down. My wattage is showing less, swr is reading a 1.2 on ch 40, & 1.3 on ch 1. which Is not really bad foe swr right? Now when I key down the tap light comes on in the other room on the other end of the house, what is causing this? Too much rf energy coming back down the coax? Can rf reflection weaken your signal as well? I didnt make a rf choke at the feed point of the antenna, as it was something I overlooked, do you think by making a rf choke at the feedpoint improve any of my issues? I red somewhere also The RF choke creates an electromagnetic field on the chokes surface, and within the donut hole. This field attracts the stray RF and chokes it off before it travels down the coax, and it is dissipated within the EM field. Hence the term "Choke". In some ways, it almost acts like a ground radial and reflects slightly the RF radiated from the antenna, to a more upwards angle sending more of the signal towards the horizon where it belongs, and not in your radio room. what do you guys think? This is one of the big disadvantages of the radial-less "stick" style antenna design. A ground plane vertical needs those radials to decouple RF. Without that counterpoise, it tends to use the shield of the coax as the counterpoise, and RF currents run down the shield and will couple into your shack and nearby homes. The coax choke should reduce this significantly. But it has to be mounted right at the feedpoint to be most effective. Another alternative would be to add the radial kit for the Imax, which should help to decouple those RF currents as they should be. Or do both. As for the differences in your wattage readings, since you raised your antenna, I assume you changed the length of coax. What that does is change the RF voltage peaks which occur roughly at every 1/2 wave. This will change what the wattmeter indicates, but not necessarily the true power. The only time a wattmeter is truly accurate, is when it is terminated into a purely resistive 50 ohm dummy load. The best you can do, is to measure your power with an accurate meter (like a Bird 43), into the dummy load. Then switch over to your antenna setup and wattmeter, and adjust it to agree with the reading you got on the calibrated dummy load setup. That's about as good as it gets, as far as accuracy goes. Yes a big disadvantage for sure, I can get a groundplane kit for it but most people say they are useless unless they are manufactured right into the antenna. I dont know either way I never ran radials. Do I have a good chance of getting rid of the rf currents by trying a choke at the feedpoint that is 8 loops and 8" across the inside loop? I will be cutting it very short on coax at this point. can I attach another 50' piece of coax without interfeering with anything or having anymore issues? Something tells me though it has to be a continuous piece without any connections. I was rinning a 50' piece of coax now I am running belden rg-8 100' length. Iam jut going off of a radio shack swr / power meter. Yeh I dont have a bird 43 or anything like that to go off of. I assume that the rf coming back down is knocking the performance down on my output correct? I got some Ideas from here www.k3dav.com/rfchokecoil.htm
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Sandbagger
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Post by Sandbagger on Oct 20, 2016 12:27:59 GMT -5
This is one of the big disadvantages of the radial-less "stick" style antenna design. A ground plane vertical needs those radials to decouple RF. Without that counterpoise, it tends to use the shield of the coax as the counterpoise, and RF currents run down the shield and will couple into your shack and nearby homes. The coax choke should reduce this significantly. But it has to be mounted right at the feedpoint to be most effective. Another alternative would be to add the radial kit for the Imax, which should help to decouple those RF currents as they should be. Or do both. As for the differences in your wattage readings, since you raised your antenna, I assume you changed the length of coax. What that does is change the RF voltage peaks which occur roughly at every 1/2 wave. This will change what the wattmeter indicates, but not necessarily the true power. The only time a wattmeter is truly accurate, is when it is terminated into a purely resistive 50 ohm dummy load. The best you can do, is to measure your power with an accurate meter (like a Bird 43), into the dummy load. Then switch over to your antenna setup and wattmeter, and adjust it to agree with the reading you got on the calibrated dummy load setup. That's about as good as it gets, as far as accuracy goes. Yes a big disadvantage for sure, I can get a groundplane kit for it but most people say they are useless unless they are manufactured right into the antenna. I dont know either way I never ran radials. Do I have a good chance of getting rid of the rf currents by trying a choke at the feedpoint that is 8 loops and 8" across the inside loop? I will be cutting it very short on coax at this point. can I attach another 50' piece of coax without interfeering with anything or having anymore issues? Something tells me though it has to be a continuous piece without any connections. I was rinning a 50' piece of coax now I am running belden rg-8 100' length. Iam jut going off of a radio shack swr / power meter. Yeh I dont have a bird 43 or anything like that to go off of. I assume that the rf coming back down is knocking the performance down on my output correct? I got some Ideas from here www.k3dav.com/rfchokecoil.htm8 - 10 tight loops of feedline over a 6- 8" diameter should be effective at 27 Mhz. You don't have to worry about it being one continuous piece of feedline. If you need more just make the choke out of an additional piece and barrel connect it. Just make sure to use coax seal to prevent water from seeping into the connection.
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Post by whitetail on Oct 26, 2016 18:31:28 GMT -5
Last wednesday I made some contacts into Wisconsin & minnesota, I kept turning back to 13 to see if I can hear anyone on the roundup. Then in the middle of the night we had a series of thunderstorms that came through, and woke me up and I jumped out of bed so fast, and threw my coax right out the window! We never get thunderstorms this late in october up here, this was a surprize. I went down stairs in the kitchen by the window and it was dead quiet at this time of night, and I herd a strange noise like electricity, then there was a flash of bright light from outside by the tower! Mind you the tower was not 100% grounded at the time, all it had was a 3' piece of rebar in the ground with a silver ground wire from the rat shack, I had it clamped to one on the tower legs and the other end to the rebar. Could this of been a static discharge from the tower? Could of what i herd was the electricity coming down the tower and the bright flash was when it hit the rebar? I went out side the next morning and lowered the tower down there was no sign of any damage to the antenna or anything. I tested the radio and worked good. Iam going to try the rf choke and see if that helps with my rf reflection, by doing this I will have to use to pieces of coax, because Im stretching 100' now. I talk to a group of people that are 40+ miles away from me, and the report wasnt what I was expecting. He said I had a stronger signal last year on the 20' pole behind the house. How can this be? Maybe The groundplane radials will help beings that we are twice the amount of distance in the air? Iam confused, I remember reading in a previous post that I will loose some power with the longer coax, that much though? Any thoughts or any help on any of these issues are appreciated, lets hear them. Here are some pictures that I know you have been waiting for.
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Post by whitetail on Oct 26, 2016 18:41:18 GMT -5
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Sandbagger
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Post by Sandbagger on Oct 27, 2016 6:05:09 GMT -5
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Sandbagger
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Posts: 6,245
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Post by Sandbagger on Oct 27, 2016 6:37:05 GMT -5
Last wednesday I made some contacts into Wisconsin & minnesota, I kept turning back to 13 to see if I can hear anyone on the roundup. Then in the middle of the night we had a series of thunderstorms that came through, and woke me up and I jumped out of bed so fast, and threw my coax right out the window! We never get thunderstorms this late in october up here, this was a surprize. I went down stairs in the kitchen by the window and it was dead quiet at this time of night, and I herd a strange noise like electricity, then there was a flash of bright light from outside by the tower! Mind you the tower was not 100% grounded at the time, all it had was a 3' piece of rebar in the ground with a silver ground wire from the rat shack, I had it clamped to one on the tower legs and the other end to the rebar. Could this of been a static discharge from the tower? Could of what i herd was the electricity coming down the tower and the bright flash was when it hit the rebar? I went out side the next morning and lowered the tower down there was no sign of any damage to the antenna or anything. I tested the radio and worked good. Iam going to try the rf choke and see if that helps with my rf reflection, by doing this I will have to use to pieces of coax, because Im stretching 100' now. I talk to a group of people that are 40+ miles away from me, and the report wasnt what I was expecting. He said I had a stronger signal last year on the 20' pole behind the house. How can this be? Maybe The groundplane radials will help beings that we are twice the amount of distance in the air? Iam confused, I remember reading in a previous post that I will loose some power with the longer coax, that much though? Any thoughts or any help on any of these issues are appreciated, lets hear them. Here are some pictures that I know you have been waiting for. View Attachment View Attachment View AttachmentOn the 11 meter band, generally speaking, the higher the antenna is, the further your signal will travel to the horizon. There should be a noticeable increase in signal between a 20' support and a 60' support. Now, feedline loss is a fact of life, but if you have good quality coax cable, the difference in loss between 50' and 100' of feedline should not make THAT much difference in signal, and the improvement in height should more than compensate for the extra loss in the feedline. Other factors could be playing a part here. If you are already at a location which is high relative to the surrounding area, the additional increase in height that the tower is giving you, may not make as drastic of a difference. Similar results can apply if you are in a deep valley where, even at the tower's additional height, you are still not clearing the surrounding mountains. Then there are the differences in the receive station to consider. Is he running the same radio? Same antenna? Same time of year? Believe it or not, if you live in an area surrounded by tall trees, the leaves and other foliage can have a detrimental affect on signal. This is usually more of a factor on VHF and UHF frequencies, but it has been seen to affect 11 meters to some degree as well. Also, there are the local band conditions to consider. If you are talking an extended direct distance (not skip), there are atmospheric phenomena which can enhance or detract from your signal making the trip to that distant station. We've already observed this phenomenon during the Wednesday night Roundup, where some nights, the distant guys in the Delco group, come in barely readable, and other times they sound like locals. Finally, there is the radiation angle of the antenna to consider. Usually a ground plane antenna with radials has a fairly low (toward the horizon) angle of radiation. This is preferable for decent local contacts, and will benefit most from a high mounting location. When you have an antenna with no radials, the radiation angle could be much higher (which might actually be better for talking skywave skip). When you raise up an antenna like this, it could put your signal over the top of the stations you want to reach in the local distance. I would continue to test your setup. Each day can bring different conditions. See if, on average, your performance has actually improved (or not). If you find that consistently you have not improved in signal, I'd check to make sure you have good feedline. Stick a dummy load and wattmeter on the antenna end and test for loss. If you put 4 watts into the cable, but only get 2 watts out, that's excessive loss. If that test passes, then I'd consider that you might need a different type of antenna, like a Alpha 5/8th, Super Penetrator, or (if you can still find them) an Interceptor 10K.
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Post by whitetail on Nov 4, 2016 8:17:43 GMT -5
Last wednesday I made some contacts into Wisconsin & minnesota, I kept turning back to 13 to see if I can hear anyone on the roundup. Then in the middle of the night we had a series of thunderstorms that came through, and woke me up and I jumped out of bed so fast, and threw my coax right out the window! We never get thunderstorms this late in october up here, this was a surprize. I went down stairs in the kitchen by the window and it was dead quiet at this time of night, and I herd a strange noise like electricity, then there was a flash of bright light from outside by the tower! Mind you the tower was not 100% grounded at the time, all it had was a 3' piece of rebar in the ground with a silver ground wire from the rat shack, I had it clamped to one on the tower legs and the other end to the rebar. Could this of been a static discharge from the tower? Could of what i herd was the electricity coming down the tower and the bright flash was when it hit the rebar? I went out side the next morning and lowered the tower down there was no sign of any damage to the antenna or anything. I tested the radio and worked good. Iam going to try the rf choke and see if that helps with my rf reflection, by doing this I will have to use to pieces of coax, because Im stretching 100' now. I talk to a group of people that are 40+ miles away from me, and the report wasnt what I was expecting. He said I had a stronger signal last year on the 20' pole behind the house. How can this be? Maybe The groundplane radials will help beings that we are twice the amount of distance in the air? Iam confused, I remember reading in a previous post that I will loose some power with the longer coax, that much though? Any thoughts or any help on any of these issues are appreciated, lets hear them. Here are some pictures that I know you have been waiting for. On the 11 meter band, generally speaking, the higher the antenna is, the further your signal will travel to the horizon. There should be a noticeable increase in signal between a 20' support and a 60' support. Now, feedline loss is a fact of life, but if you have good quality coax cable, the difference in loss between 50' and 100' of feedline should not make THAT much difference in signal, and the improvement in height should more than compensate for the extra loss in the feedline. Other factors could be playing a part here. If you are already at a location which is high relative to the surrounding area, the additional increase in height that the tower is giving you, may not make as drastic of a difference. Similar results can apply if you are in a deep valley where, even at the tower's additional height, you are still not clearing the surrounding mountains. Then there are the differences in the receive station to consider. Is he running the same radio? Same antenna? Same time of year? Believe it or not, if you live in an area surrounded by tall trees, the leaves and other foliage can have a detrimental affect on signal. This is usually more of a factor on VHF and UHF frequencies, but it has been seen to affect 11 meters to some degree as well. Also, there are the local band conditions to consider. If you are talking an extended direct distance (not skip), there are atmospheric phenomena which can enhance or detract from your signal making the trip to that distant station. We've already observed this phenomenon during the Wednesday night Roundup, where some nights, the distant guys in the Delco group, come in barely readable, and other times they sound like locals. Finally, there is the radiation angle of the antenna to consider. Usually a ground plane antenna with radials has a fairly low (toward the horizon) angle of radiation. This is preferable for decent local contacts, and will benefit most from a high mounting location. When you have an antenna with no radials, the radiation angle could be much higher (which might actually be better for talking skywave skip). When you raise up an antenna like this, it could put your signal over the top of the stations you want to reach in the local distance. I would continue to test your setup. Each day can bring different conditions. See if, on average, your performance has actually improved (or not). If you find that consistently you have not improved in signal, I'd check to make sure you have good feedline. Stick a dummy load and wattmeter on the antenna end and test for loss. If you put 4 watts into the cable, but only get 2 watts out, that's excessive loss. If that test passes, then I'd consider that you might need a different type of antenna, like a Alpha 5/8th, Super Penetrator, or (if you can still find them) an Interceptor 10K. Sandbagger, All the information is coming together now and making sense. So you know My location is is up on a mountain plateau at 2,300 elevation. Because my antenna is up higher it can see further to the horizon. Lets talk about my buddy 40 miles away, Sitting at 1,400ft. Same time of year testing. He always said I was a good solid 4s units now, Iam at a 1s unit. This is because my antenna is higher now my signal is now skipping somewhat past him correct? So my local conversations wont be as strong of signal but I will still be heard? I hate to get another antenna because I know the Imax can talk, I talked to alaska to Wales England, and many more locations. I know I cant have the best of both worlds, with a strong signal locally and dx. Do you think a groundplane on the Imax will help me out any, locally &dx? I know others say dont waste the money it doesnt do anything, but every setup is different and will perform diffferent as well. I looked at the groundplane for the imax ant these (4) 6'radials point down at a 45* angle, while other antennas radials point straight out at a 90*angle. What is the differnce here? Iam using belden RG-8 coax, 100' run, if I do a rf choke at the feed point I will have to get another 50' and have a connection in between. I was considering the hy=gain spt-500 penetrator antenna www.hy-gain.com/Product.php?productid=SPT-500 . Iam sure you herd of this antenna back in the late 70's and 80's. People loved them (just going by other posts I red) Thanks for helping me out, Iam slowly learning as things develop on this end, and now it is making sense in the prev posts of antenna height and signal to the horizon! Thanks
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Sandbagger
Administrator/The Boss
Posts: 6,245
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Post by Sandbagger on Nov 4, 2016 10:21:33 GMT -5
On the 11 meter band, generally speaking, the higher the antenna is, the further your signal will travel to the horizon. There should be a noticeable increase in signal between a 20' support and a 60' support. Now, feedline loss is a fact of life, but if you have good quality coax cable, the difference in loss between 50' and 100' of feedline should not make THAT much difference in signal, and the improvement in height should more than compensate for the extra loss in the feedline. Other factors could be playing a part here. If you are already at a location which is high relative to the surrounding area, the additional increase in height that the tower is giving you, may not make as drastic of a difference. Similar results can apply if you are in a deep valley where, even at the tower's additional height, you are still not clearing the surrounding mountains. Then there are the differences in the receive station to consider. Is he running the same radio? Same antenna? Same time of year? Believe it or not, if you live in an area surrounded by tall trees, the leaves and other foliage can have a detrimental affect on signal. This is usually more of a factor on VHF and UHF frequencies, but it has been seen to affect 11 meters to some degree as well. Also, there are the local band conditions to consider. If you are talking an extended direct distance (not skip), there are atmospheric phenomena which can enhance or detract from your signal making the trip to that distant station. We've already observed this phenomenon during the Wednesday night Roundup, where some nights, the distant guys in the Delco group, come in barely readable, and other times they sound like locals. Finally, there is the radiation angle of the antenna to consider. Usually a ground plane antenna with radials has a fairly low (toward the horizon) angle of radiation. This is preferable for decent local contacts, and will benefit most from a high mounting location. When you have an antenna with no radials, the radiation angle could be much higher (which might actually be better for talking skywave skip). When you raise up an antenna like this, it could put your signal over the top of the stations you want to reach in the local distance. I would continue to test your setup. Each day can bring different conditions. See if, on average, your performance has actually improved (or not). If you find that consistently you have not improved in signal, I'd check to make sure you have good feedline. Stick a dummy load and wattmeter on the antenna end and test for loss. If you put 4 watts into the cable, but only get 2 watts out, that's excessive loss. If that test passes, then I'd consider that you might need a different type of antenna, like a Alpha 5/8th, Super Penetrator, or (if you can still find them) an Interceptor 10K. Sandbagger, All the information is coming together now and making sense. So you know My location is is up on a mountain plateau at 2,300 elevation. Because my antenna is up higher it can see further to the horizon. Lets talk about my buddy 40 miles away, Sitting at 1,400ft. Same time of year testing. He always said I was a good solid 4s units now, Iam at a 1s unit. This is because my antenna is higher now my signal is now skipping somewhat past him correct? So my local conversations wont be as strong of signal but I will still be heard? I hate to get another antenna because I know the Imax can talk, I talked to alaska to Wales England, and many more locations. I know I cant have the best of both worlds, with a strong signal locally and dx. Do you think a groundplane on the Imax will help me out any, locally &dx? I know others say dont waste the money it doesnt do anything, but every setup is different and will perform diffferent as well. I looked at the groundplane for the imax ant these (4) 6'radials point down at a 45* angle, while other antennas radials point straight out at a 90*angle. What is the differnce here? Iam using belden RG-8 coax, 100' run, if I do a rf choke at the feed point I will have to get another 50' and have a connection in between. I was considering the hy=gain spt-500 penetrator antenna www.hy-gain.com/Product.php?productid=SPT-500 . Iam sure you herd of this antenna back in the late 70's and 80's. People loved them (just going by other posts I red) Thanks for helping me out, Iam slowly learning as things develop on this end, and now it is making sense in the prev posts of antenna height and signal to the horizon! Thanks I can't really give you a solid, one-size-fits-all answer because the nature of RF varies and what works in one situation may not work in another. But it does sound like you are way up in height, with nothing blocking your signal. So the higher tower might be putting your signal over top of those lower in height. Then again, I would not put all of your money on what one other station reports back. You should try to get reports from several other people, and gauge whether or not your line-of-sight local path has improved or not. I would not put much weight in skip contacts. You can be in the bottom of a valley and still do well via sky wave, as long as you have an unobstructed path to the sky. So 40 or 50 more feet should not make any difference in skipland. Although if the additional height changes your radiation angle, THAT may make a difference both locally and DX. I don't have personal experience with the radial kit for the Imax. I have read reports that have said that it improved performance, and other reports that said just the opposite. So I can neither recommend it or not. I was a big fan of the Super Penetrator antenna back in the day. It was the best ground plane you could get. You wouldn't go wrong with an antenna like that. Given your height, you'd probably also do well with an Astroplane type antenna, as that had a very low angle of radiation, which you need at your height. You should not need 50' of additional feedline to make an 8 turn, 8" diameter choke. I would think you'd get by with less than 20'. RG-8 cable has much less loss than RG-58, but it's not as good as RG-213 or LMR-400. At 100', you should have about 1db of loss. If you ran LMR400, that loss would drop to .6db. Here's a handy cable loss calculator, that you can use to compare different coaxial cable ratings: www.timesmicrowave.com/calculator/
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