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Aluminum tubing for vertical antenna
Hello everyone,
I'm contemplating putting up a vertical antenna for HF use. I'm looking at an approximate height of 30 feet or so. I am thinking of using aluminum tubing (0.058" wall) in a 'telescoping' manner. Here are my questions (so far): 1) Diameter. For wind resistance, should I start with something like 1 inch diameter and work down to 3/8 inch? Would the antenna be stronger if I started with 2 inch diameter and worked down to 1-3/8 inch? It would seem to me that the larger diameter might be better able to withstand wind but it would also offer more resistance to wind possibly negating the additional strength. But, I have no experience to draw from. So, fat or slim? 2) I am planning a set of guy ropes at about the 12 foot level, a bit over 1/3 height. Is there a better height for guy ropes? I can put as much concrete in the ground as I like, and a very robust mount system is possible. Is there any way to make an unguyed 30 footer that isn't a tower form factor? Something like making the bottom 12 feet or so from 2 inch diameter, 1/4 inch wall tubing and then light weight tubing from there up to full height? -- 73, Hank |
Aluminum tubing for vertical antenna
Hank Zoeller wrote:
Hello everyone, I'm contemplating putting up a vertical antenna for HF use. I'm looking at an approximate height of 30 feet or so. I am thinking of using aluminum tubing (0.058" wall) in a 'telescoping' manner. Here are my questions (so far): 1) Diameter. For wind resistance, should I start with something like 1 inch diameter and work down to 3/8 inch? Would the antenna be stronger if I started with 2 inch diameter and worked down to 1-3/8 inch? It would seem to me that the larger diameter might be better able to withstand wind but it would also offer more resistance to wind possibly negating the additional strength. But, I have no experience to draw from. So, fat or slim? 2) I am planning a set of guy ropes at about the 12 foot level, a bit over 1/3 height. Is there a better height for guy ropes? I can put as much concrete in the ground as I like, and a very robust mount system is possible. Is there any way to make an unguyed 30 footer that isn't a tower form factor? Something like making the bottom 12 feet or so from 2 inch diameter, 1/4 inch wall tubing and then light weight tubing from there up to full height? When I bought my aluminum tubing from Texas Towers, they had a computer program that calculated and specified all of the above. http://www.texastowers.com -- 73, Cecil http://www.qsl.net/w5dxp |
Aluminum tubing for vertical antenna
The windload on a piece of tubing of a given height is proportional to
the radius, but the stiffness of a piece of tubing is proportional to the fourth power of radius. So, as you make the tubing bigger, the stiffness goes up much much faster than the windload, so bigger tubing will always be stronger unless you make the wall very, very thin compared to that of the smaller tubing. Now, the weight of the piece goes up too, and the price is proportional to the weight, so you don't see a lot of antennas made of 5 inch aluminum tubing when they don't need to be. For a freestanding vertical, you're going to get the best results with a taper. It's good for the tubing to get thinner as you go up, because the big problem with a freestanding pole is that the wind is trying to tip it over. The mount at the base has to be strong enough to take this torque. The wind has more leverage when it's acting on the tip of the vertical than when it's acting further down, so having the vertical thin at the top helps reduce the load on the base. Cecil's suggestion about the Texas Towers calculator is a good one. Also, after you put up a vertical you'll have more intuition about this. I wouldn't make it a 1 inch vertical all the way up :-). I had a 40m vertical, 4 elevated radials at 15 feet and 1 inch tubing from that point up to about 25 feet, with smaller tapered tubing and rod above that. It worked OK, but had to be guyed in two places! It also snapped in half in a windstorm. Bad mechanical design, but I made do because I had the tubing. It would have been a much nicer antenna if I'd purchased the proper materials. 73, Dan |
Aluminum tubing for vertical antenna
How are you planning on mounting the alum. tubing at ground level?
And what, if any, means are you considering to provide for tipping it over? I wonder if it is practical to install say, 4X4 posts in the ground about 5 inches apart, with another 4X4 as the vertical support for the aluminum pole. The aluminum pole bolted to the 8 foot long 4X4 at about the 6 foot level. Would the wood detune the antenna? Rick K2XT |
Aluminum tubing for vertical antenna
Rick wrote:
How are you planning on mounting the alum. tubing at ground level? And what, if any, means are you considering to provide for tipping it over? I wonder if it is practical to install say, 4X4 posts in the ground about 5 inches apart, with another 4X4 as the vertical support for the aluminum pole. The aluminum pole bolted to the 8 foot long 4X4 at about the 6 foot level. Would the wood detune the antenna? I have mine with the bottom mounted at 20 ft using 2x4s. The tubing is isolated from the 2x4s by a sleeve of PVC pipe. There is no noticeable detuning by the wood support. -- 73, Cecil http://www.qsl.net/w5dxp |
Aluminum tubing for vertical antenna
Cecil Moore wrote:
When I bought my aluminum tubing from Texas Towers, they had a computer program that calculated and specified all of the above. http://www.texastowers.com Cool! Does it calculate the size to use based on expected wind speed? I looked around on their web site and didn't find a calculator so it must be something they do with you on the phone? I'll call 'em Monday and see what they have to say. Thanks for the tip! -- 73, Hank |
Aluminum tubing for vertical antenna
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Aluminum tubing for vertical antenna
Rick wrote:
How are you planning on mounting the alum. tubing at ground level? And what, if any, means are you considering to provide for tipping it over? I haven't yet decided how I'm going to mount this thing. Now, I'm leaning toward (pun intended) a larger size of tubing than I initially thought. Once I make a final determination on the tubing size then I'll turn my attention to the mount. Fortunately, I have a machine shop so I ought to be able to fabricate something worthy. As to the detuning, I'm not concerned at all about resonance as I'll have a 1-kw antenna coupler mounted at the base of the vertical. I would be concerned about other effects so I'll likely make the mount with as small an electrical footprint as possible. The fold-over idea is good. I think I'll probably make two of these things, one about 30 feet high and another about 16 feet high for the upper HF bands. It would be cool to be able to switch them out easily.. -- 73, Hank |
Aluminum tubing for vertical antenna
For about 20 - 25 years I've had four verticals of about 33 foot height
in my back yard. They're free standing, no guys. They went through one wind storm with gusts in the 80 mph range, and all other weather, without damage. Each is made of three pieces of telescoping 6061-T6 tubing, 1-1/4, 1-1/8, and 1 inch diameter. The support is an 8 foot chain link fence line pole (about 1-1/2 inch diameter, steel), driven 4 feet into the clay ground. The antenna element is clamped to it with muffler clamps, insulated with a couple of slices of thick wall plastic conduit about 1/4 inch thick. Roy Lewallen, W7EL Hank Zoeller wrote: Hello everyone, I'm contemplating putting up a vertical antenna for HF use. I'm looking at an approximate height of 30 feet or so. I am thinking of using aluminum tubing (0.058" wall) in a 'telescoping' manner. Here are my questions (so far): 1) Diameter. For wind resistance, should I start with something like 1 inch diameter and work down to 3/8 inch? Would the antenna be stronger if I started with 2 inch diameter and worked down to 1-3/8 inch? It would seem to me that the larger diameter might be better able to withstand wind but it would also offer more resistance to wind possibly negating the additional strength. But, I have no experience to draw from. So, fat or slim? 2) I am planning a set of guy ropes at about the 12 foot level, a bit over 1/3 height. Is there a better height for guy ropes? I can put as much concrete in the ground as I like, and a very robust mount system is possible. Is there any way to make an unguyed 30 footer that isn't a tower form factor? Something like making the bottom 12 feet or so from 2 inch diameter, 1/4 inch wall tubing and then light weight tubing from there up to full height? |
Aluminum tubing for vertical antenna
Hank Zoeller wrote:
Cool! Does it calculate the size to use based on expected wind speed? As I remember, you give them the wind speed and they give you back the specifications. They ran the program for me while I was standing there in the lobby wondering what size to buy. I requested a self-supporting 33 ft monopole rated at 75 mph but changed my mind when I found out what that required - more than double the cost of a guyed monopole. Also building it out of six foot sections instead of 12 foot sections reduced the cost considerably. ME's probably understand why but, as a EE, I was surprised. -- 73, Cecil http://www.qsl.net/w5dxp |
Aluminum tubing for vertical antenna
I took scrap pieces of aluminum tubing lying around, not being particularly
careful of sizes as along they fit snugly into adjacent pieces when they were slotted. I used hose clamps. I made it 33ft and 3 inches tall (1/4 wave on 40). It has 32 radials of various lengths for the non-WARC ham bands 40 meters and higher. 16 of them are 34 feet long for 40. SWR on 40 meters is 1.2 to 1 without any adjustment at 7100. The vertical covers the entire band. I use a Palstar AT1500CV transmatch on other bands and run 700 watts when needed. I can work anything I can hear and I work tons of DX. The antenna is very quiet for a vertical. The Palstar has no problem matching this vertical on all bands 40 through 6 meters including WARC though 12 meters is the trickiest. Works much DX on all bands whenever I try Peter I Island, Kiribati, etc., though I use other antennas on bands other than 40 cut appropriately. Cost of the antenna was $0.00. I used scrap tubing, scrap #12 or thicker radial wire, leftover rope for 3 guys at 18 feet, leftover 4BTV base. This antenna has been up for months on a hill at 1100 feet and survived 80 mph plus gusts. "Hank Zoeller" wrote in message ... Hello everyone, I'm contemplating putting up a vertical antenna for HF use. I'm looking at an approximate height of 30 feet or so. I am thinking of using aluminum tubing (0.058" wall) in a 'telescoping' manner. Here are my questions (so far): 1) Diameter. For wind resistance, should I start with something like 1 inch diameter and work down to 3/8 inch? Would the antenna be stronger if I started with 2 inch diameter and worked down to 1-3/8 inch? It would seem to me that the larger diameter might be better able to withstand wind but it would also offer more resistance to wind possibly negating the additional strength. But, I have no experience to draw from. So, fat or slim? 2) I am planning a set of guy ropes at about the 12 foot level, a bit over 1/3 height. Is there a better height for guy ropes? I can put as much concrete in the ground as I like, and a very robust mount system is possible. Is there any way to make an unguyed 30 footer that isn't a tower form factor? Something like making the bottom 12 feet or so from 2 inch diameter, 1/4 inch wall tubing and then light weight tubing from there up to full height? -- 73, Hank |
Aluminum tubing for vertical antenna
Jozef wrote:
I took scrap pieces of aluminum tubing lying around, not being particularly careful of sizes as along they fit snugly into adjacent pieces when they were slotted. I used hose clamps. I made it 33ft and 3 inches tall (1/4 wave on 40)... The Palstar has no problem matching this vertical on all bands 40 through 6 meters including WARC though 12 meters is the trickiest. That antenna is 5/8 wavelength on ~17.5 MHz. Above 21 MHz, most of the radiation is lost at a high elevation angle. Such an antenna is a poor performer on 15m, 12m, 10m, and 6m. Matching doesn't mean much for a monopole appreciably longer than 5/8 wavelength. -- 73, Cecil http://www.qsl.net/w5dxp |
Aluminum tubing for vertical antenna
Cecil Moore wrote:
Jozef wrote: I took scrap pieces of aluminum tubing lying around, not being particularly careful of sizes as along they fit snugly into adjacent pieces when they were slotted. I used hose clamps. I made it 33ft and 3 inches tall (1/4 wave on 40)... The Palstar has no problem matching this vertical on all bands 40 through 6 meters including WARC though 12 meters is the trickiest. That antenna is 5/8 wavelength on ~17.5 MHz. Above 21 MHz, most of the radiation is lost at a high elevation angle. Such an antenna is a poor performer on 15m, 12m, 10m, and 6m. Matching doesn't mean much for a monopole appreciably longer than 5/8 wavelength. -- 73, Cecil http://www.qsl.net/w5dxp I have an almost identical vertical with a relay controlled loading coil I switch in for 160 and 80M and a SGC tuner. Works great 160 to 30M. Marginal at 20M and goes to poor from there up. -- Jim Pennino Remove .spam.sux to reply. |
Aluminum tubing for vertical antenna
I understand that which is why in my original post I said, "Works much DX on
all bands whenever I try Peter I Island, Kiribati, etc., though I use other antennas on bands other than 40 cut appropriately." Perhaps, you missed that? Theory granted, you're also make a case against success. It works. Though as you suggest, with handicaps. "Cecil Moore" wrote in message .com... Jozef wrote: I took scrap pieces of aluminum tubing lying around, not being particularly careful of sizes as along they fit snugly into adjacent pieces when they were slotted. I used hose clamps. I made it 33ft and 3 inches tall (1/4 wave on 40)... The Palstar has no problem matching this vertical on all bands 40 through 6 meters including WARC though 12 meters is the trickiest. That antenna is 5/8 wavelength on ~17.5 MHz. Above 21 MHz, most of the radiation is lost at a high elevation angle. Such an antenna is a poor performer on 15m, 12m, 10m, and 6m. Matching doesn't mean much for a monopole appreciably longer than 5/8 wavelength. -- 73, Cecil http://www.qsl.net/w5dxp |
Aluminum tubing for vertical antenna
Roy Lewallen wrote:
For about 20 - 25 years I've had four verticals of about 33 foot height in my back yard. They're free standing, no guys. They went through one wind storm with gusts in the 80 mph range, and all other weather, without damage. Each is made of three pieces of telescoping 6061-T6 tubing, 1-1/4, 1-1/8, and 1 inch diameter. [trimmed] Roy, Thank you very much. There's nothing like tapping the experience of others. I'm really happy to hear I can build a freestanding vertical! (But, I'll buy some spare aluminum anyway..) -- 73, Hank |
Aluminum tubing for vertical antenna
Jozef wrote:
I neglected to provide the following links: http://www.metaphoria.us/hamradio/40monoband.htm for the 40 meter monobander vertical http://www.metaphoria.us/hamradio/4BTV.htm for the base with radials. The radials are now covered by grass that I mow with a hand manual non-powered Scott's push mower. Jozef, What did you use for staples for the radials? Thanks, -- 73, Hank |
Aluminum tubing for vertical antenna
Hank,
Just wanted to add that you don't need 1/4 inch wall stuff anywhere in a 33 foot vertical. If you have it lying around you could use it, but the extra weight really isn't worth it. Same for reinforcing by thickening the tubing on the inside. A hollow tube 2" in diameter with 0.058" walls is about 3 times stiffer than a SOLID 1" rod. Now, strength and stiffness are two different things, but you're better taking the aluminum and making a fairly thin wall tube of large diameter if you're trying to make a strong, stiff element. For the price of one 12 foot 1/4" wall 2" tube you can buy the whole vertical in 2" 0.058 wall tubing and the next telescoping size for joints. 1/4" wall would be good if you're going to guy it and put a tribander on top! I'd go with Roy's vertical design, in fact. My antenna was a mess of found aluminum, tent poles, etc. Might have even been 7/8" now that I think of it. This means that Roy's bottom section, if 0.058 wall 1.25" diameter 6061 was at LEAST 3 times as stiff as my 7/8" OD 3/4" ID 1/16" wall stuff, and that's assuming I was using a good, stiff grade of aluminum, which I wasn't. Incidentally, Cecil, I think the 12 footers are more expensive because you can UPS ship 6 footers anywhere and can't do that with 12 footers... it may be that it's just cheaper to keep the 6 footers in stock because the market is bigger. Could also be that it's cheaper for TX Towers to get them in .... dunno. It's too bad though, 12 foot continuous sections would be good for this sort of thing. 73, Dan |
Aluminum tubing for vertical antenna
|
Aluminum tubing for vertical antenna
"Hank Zoeller" wrote in message ... Hello everyone, I'm contemplating putting up a vertical antenna for HF use. I'm looking at an approximate height of 30 feet or so. I am thinking of using aluminum tubing (0.058" wall) in a 'telescoping' manner. Here are my questions (so far): 1) Diameter. For wind resistance, should I start with something like 1 inch diameter and work down to 3/8 inch? Would the antenna be stronger if I started with 2 inch diameter and worked down to 1-3/8 inch? It would seem to me that the larger diameter might be better able to withstand wind but it would also offer more resistance to wind possibly negating the additional strength. But, I have no experience to draw from. So, fat or slim? 2) I am planning a set of guy ropes at about the 12 foot level, a bit over 1/3 height. Is there a better height for guy ropes? I can put as much concrete in the ground as I like, and a very robust mount system is possible. Is there any way to make an unguyed 30 footer that isn't a tower form factor? Something like making the bottom 12 feet or so from 2 inch diameter, 1/4 inch wall tubing and then light weight tubing from there up to full height? -- 73, Hank http://www.valcom.ca/Guelph/products...b-u_photo.html This is built for navy shipboard use so it may be "scary expensive." These are virtually indestructible. You have to hit one with a crane boom to break it. It is exactly what you described in your last paragraph. This size whip covers 2 - 30 MHz with a tuner. The Navy has used many 35-foot whips over the years. There were five-section versions, but any you found now would probably be too corroded to be of use. |
Aluminum tubing for vertical antenna
Sal M. Onella wrote:
http://www.valcom.ca/Guelph/products...b-u_photo.html This is built for navy shipboard use so it may be "scary expensive." These are virtually indestructible. You have to hit one with a crane boom to break it. It is exactly what you described in your last paragraph. This size whip covers 2 - 30 MHz with a tuner. The Navy has used many 35-foot whips over the years. There were five-section versions, but any you found now would probably be too corroded to be of use. Actually, I *did* find one of those things! http://www.american-milspec.com/p961.html Alas, it's a bit too tall for my use. I'm thinking of using a 26' whip with a remote coupler (Harris RF-601) for operating from 40 through 15 meters. Or, I might go to a 30' whip for ops on 60 through 18 meters. I haven't made up my mind yet although I'm leaning toward the 26' version. If I go that route I might pick up a commercial, little brother of that massive Navy style whip - the Shakespeare 5300. It's sold as a 28' whip but it's actually 26' as they use the bottom two feet for a mounting sleeve. It's made for shipboard use but is substantially lighter than the Navy 35' whip. It's only 2-3/8" in diameter, for example.. Time is a precious commodity, at the moment, but I still might roll my own from Texas Towers Aluminum. 73, -- HZ |
Aluminum tubing for vertical antenna
Sal M. Onella wrote:
"Hank Zoeller" wrote in message ... Hello everyone, I'm contemplating putting up a vertical antenna for HF use. I'm looking at an approximate height of 30 feet or so. I am thinking of using aluminum tubing (0.058" wall) in a 'telescoping' manner. Here are my questions (so far): 1) Diameter. For wind resistance, should I start with something like 1 inch diameter and work down to 3/8 inch? Would the antenna be stronger if I started with 2 inch diameter and worked down to 1-3/8 inch? It would seem to me that the larger diameter might be better able to withstand wind but it would also offer more resistance to wind possibly negating the additional strength. But, I have no experience to draw from. So, fat or slim? 2) I am planning a set of guy ropes at about the 12 foot level, a bit over 1/3 height. Is there a better height for guy ropes? I can put as much concrete in the ground as I like, and a very robust mount system is possible. Is there any way to make an unguyed 30 footer that isn't a tower form factor? Something like making the bottom 12 feet or so from 2 inch diameter, 1/4 inch wall tubing and then light weight tubing from there up to full height? -- 73, Hank http://www.valcom.ca/Guelph/products...b-u_photo.html This is built for navy shipboard use so it may be "scary expensive." These are virtually indestructible. You have to hit one with a crane boom to break it. It is exactly what you described in your last paragraph. This size whip covers 2 - 30 MHz with a tuner. The Navy has used many 35-foot whips over the years. There were five-section versions, but any you found now would probably be too corroded to be of use. Just look in the ARRL hanbook and use their 40 meter beam elements. They self supporting and have a wind rating of 90mph. In a vertical configuration with guys they would never blow down in a 100 years. Dont forget the Navy Whips by valcom etc were designed to take a take from a wave etc. Tons of water would bend any noodle. They really a overkill. Some were also designed to take shock blasts from canons etc and fatigue from 20,000 rounds weakening the metal. Theres a lot of Yagi element stress element software around, i would use it and design it to your spec. I would make sure you use 6061 which is the most corrosion resistant and has the most strength. Array Solutions sells element stress software from some Ham Kurt Andress or something like that. ON4un also has some free software with his latest book. How you gonna tune this beast on all bands? Would be interested to hear how you going about this. Pat |
Aluminum tubing for vertical antenna
Bitz wrote:
How you gonna tune this beast on all bands? Would be interested to hear how you going about this. [Not sure you are asking me or Sal about this but I'll answer for me.] Same way the Navy does it! With a Harris RF-601 remote antenna coupler. Only way to go in my view.. But, for the record, I'm not planning on using it on all bands -- only on the bands where it has some chance of being an effective radiator. That's why I'm thinking of either 30' (60 thru 17 meters) or 26' (40 thru 15 meters). 73, -- HZ |
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