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1-6 of 6 messages
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Flagpole antenna?
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by KC0BUS on August 25, 2005
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I'm wanting to disguise a Hustler 5BTV vertical antenna as a flagpole as per the plans on DX Engineering's website and as also seen in the May 1993 issue of QST magazine on page 65. Here's the link, once there, click on the .pdf file near the middle of the page.
http://www.dxengineering.com/Parts.asp?ID=178&PLID=141&SecID=63&DeptID=22&PartNo=HUS%2D5%2DBTV
Hustler's 4BTV/5BTV/6BTV antennas are notorious for swinging and swaying in even the most gentle of breezes. So you can imagine what they do in a strong wind! ;-) I had a 4BTV in the past and it swinged and swayed so much that it finally ended up bending slightly in the middle. (though I've never actually seen one break).
My question is this; if I encase the antenna in 2" thin wall PVC pipe from top to bottom, add on all the flag hardware- pully, rope, tie-off, ball on top, flag, etc. throw in a stiff breeze and the ocassional North American winter ice storm, won't all this extra weight on this flimsy antenna be like a disaster waiting to happen? Or will the PVC act like a stiffner and brace up the whole works? Although this radical modification is something of a well known trick, I am very skeptical at best of this setup. This becomes especially worrisome for the much taller 5BTV and 6BTV antennas. Personally, I would feel a whole heck of a lot better about guying such a setup but I don't know very much about guying. How would you guy something like this? Would you guy it at about 2/3 up the top of the mast just like a tower? How far out at the bottom would you anchor the guy wires? Would I still be able to raise and lower the flag with a set of 3 guy wires in the way? Would you be suspicious of a flagpole with guy wires coming off of it? ;-)
Many thanks,
Scott, KC0BUS
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RE: Flagpole antenna?
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by KA5N on August 25, 2005
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I suppose you intend to ground mount the antenna. I would use schedule 80 PVC if I was worried about stability. The Hustler inside the schedule 80 should be pretty stiff. I don't see a problem with raising a flag if the pole is guyed. You have to run a rope through the pully at the top and back to the base and tie the rope ends together to make a continuous loop. When you raise or lower the flag you hold it away from the pole and any guys.
As for guying, probably one set of three at the top would be enough. The angle to the earth should be 45 to 60 degrees. If the angle is too acute, the guys will be useless. Also, what's this deal about guying 2/3 up on a tower? Never heard of such a thing. The number of guys is determined by the prevailing weather conditions. Worst case would be three sets of three guys. One set every ten feet. Dacron cord is probably ideal as wire guys would tend to couple into the vertical.
Good Luck
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RE: Flagpole antenna?
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by WW5AA on August 26, 2005
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Also check and make sure the PVC does not contain carbon fiber or metal (some PVC has both!) Hustler recomends guying the BTV just below the 20 meter trap. My 5BTV is roof mounted on a 3' tripod, the 12 tuned radials act as guying to an extent(radials are 45 degree drop from BTV base to the roof). Have had several storms with high winds without a problem.
Good luck and have fun, de Lindy
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RE: Flagpole antenna?
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by N4ZOU on August 26, 2005
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Check this article,
http://www.eham.net/articles/11473
This will work just fine with your antenna or one of the Butternut HF vertical antennas with the exception of the 30 and 160-meter resonator coils as they hang off the side of the antenna elements. I know of one setup using the light poles around a circular drive where 4 of the poles contained Butternut HF5V antennas that were setup as a 4 square array. An L-network and relays provided direction control of the gain lobe in any direction.
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RE: Flagpole antenna?
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by WB2WIK on August 26, 2005
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I don't like the idea of putting the BTV vertical inside PVC and then using that whole assembly for a flagpole, or "guying" a flagpole, which draws a lot of attention to it -- since flagpoles aren't guyed.
I would recommend the Force-12 Flagpole Antenna Kit, which is very simple and works surprisingly well (I've installed two of them), especially if you use the extension mast sections to make it "taller." It comes standard at about 16' height, but you can add more sections in 4' increments and make it about 20' or 24' and it's still absolutely strong enough to self-support, without guys, and while holding a flag, in very strong winds. It's lightweight aluminum tubing but pretty thick walled and very strong. And since it has no traps or loading coils or anything, its weight is linearly distributed from bottom to top, with no heavy spots or weak spots anywhere.
It comes complete with the flag, rope and halyard. It's painted white and looks exactly like an ordinary flagpole. It goes together in five minutes and requires no adjustments.
What it does require is radials, which of course you'd also need for the Hustler vertical, and an antenna tuner since it's not really resonant anywhere other than by coincidence (depends on how tall you make it). You must install it in a special thick wall PVC base pipe (also supplied by Force-12, with the antenna)embedded in cement. That's where all its strength comes from. But we found just over one bag of Redi-Mix concrete (60 lbs) and a hole dug with a post hole digger in about 15 minutes was sufficient.
My friend Stu, WA6NCN, has one with two 4' extensions and he uses it with an LDG 100 autotuner and eight radials (not enough), and it works quite well. I was there last Saturday around noontime to check things out, called one "CQ" on 17m and got a "59 Plus" report from a fellow in Michigan (we're in L.A.) immediately. It does work. It's not a beam, or even a good dipole, but it makes contacts and draws no attention.
Link to this antenna:
http://force12inc.com/F12-flagpole-ants-003.htm
WB2WIK/6
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RE: Flagpole antenna?
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by W0FM on August 26, 2005
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In 1987, I built a couple flagpole antennas that you describe with the Hustler 4BTV and 5BVT using schedule 40 PVC. The 'BTV was ground mounted. After getting the antenna tuned up, I removed it from the ground mount. Then I slid the entire antenna into a length of PVC slightly longer than the antenna itself. I painted one of the flagpoles a brownish bronze color (non-metalic paint) and other one flat white. Both got a pully at the top and cord to hoist a flag, (although I never got around to actually putting up a flag.) I painted a child's plastic ball gold and glued it to the top of the flagpole.
Both of these antennas survived Midwest storms and ice for many years with no damage. I did not guy the antenna as it wouldn't look much like a flagpole if it were guyed. You may need to tweak the tuning of the antenna after it is encased in the PVC.
The condo cops never had a clue.
Give it a try. It worked well for me.
73,
Terry, WØFM
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