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1-10 of 13 messages
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Chimney mount for center inverted V support
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by COMINGBACK on October 19, 2009
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Hi, I am quite restricted on what I can do in my neighborhood antenna-wise. Therefore, I've constructed a simple inverted V dipole with fairly thin (18 gauge) copper clad solid wire. This will be fed with 450 ohm window line.
I do not have suitable trees from which to support the dipole. The only way I can get any height whatsoever is to use my chimney as a foundation for a center support. The chimney, and about 10 feet above it, is obscured from view from both the front and back of the house, so it will be quite undetectable.
I purchased a chimney mount for standard TV-grade aluminum mast. The chimney is in good shape (visually), and is not used for its intended purpose. Can I get away with 10 ft of un-guyed above-chimney mast if it's used solely for a center support?
Thanks in advance,
Bill
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RE: Chimney mount for center inverted V support
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by AA4PB on October 19, 2009
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Since it is not in very good shape, I don't think anyone here (without inspecting it) could possibly tell you with any degree of certainty. If you want to be reasonably sure you need to get someone locally with construction experience to take a look at it.
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RE: Chimney mount for center inverted V support
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by COMINGBACK on October 19, 2009
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Sorry, it IS in pretty good shape. No loose bricks, mortar, etc.
Thanks,
Bill
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RE: Chimney mount for center inverted V support
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by AA4PB on October 19, 2009
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Sorry, I misread that. I've put up plenty of TV antennas using chimney mounts and 10-foot masts so you shouldn't have an problem with the V support. Try to make the wires at 180 deg apart if you can so that they don't tend to pull that mast to one side.
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RE: Chimney mount for center inverted V support
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by N5LRZ on October 19, 2009
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BEFORE YOU DO ANYTHING...
Contact your personal legal rep and have them read your purchase agreement, which you did sign with full consent remember, to see what LEGAL APPROVALS you will need.
OBEY THE TERMS OF YOUR CONTRACT OBEY OBEY OBEY...IF caught it could cost you serious fines for breach of contract not to mention legal fees and court expenses if a HOA drags you to court (for said breech of contract) SOOOOO GET with YOUR lawyer first and get all the legal approvals as required before you do anything else.
But lets take it that you are not hindered to the point where you cannot LEGALLY put up an external antenna.
A chimney is not a very strong support structure. IF you do put up an inverted V or other structure be sure to take this into account. Should lightning strike your antenna your chimney may be damaged along with your radio, and the antenna itself.
The second problem is that a chimney is under normal circumstances not very high to begin with when using low bands. In order to keep the ground from turning your antenna into a vertical mode antenna you are going to have to get that feedpoint at the very least one full quarter wave above the ground for the lowest frequency you intend to use. Higher than a half wave would be even better. At any rate, you need to put that antenna as high as is possible--tall trees are good for this kind of thing.
And most important is the use of the proper size of wire for wire antennas. The use of small diameter wire leads to more frequent breakage and maintenance. The wind will cause the wire to flex causing thin wire to break and pulling on the wire does not help either. You need to use a stranded wire large enough to take a little abuse...I strongly urge no less than #14 stranded found at any home improvement stores.
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RE: Chimney mount for center inverted V support
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by COMINGBACK on October 19, 2009
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Thanks. Yes, I've scrutinized my HOA contract. Basically they can ask me to take it down before any action can occur. Same as if I installed a new fence or an addition to the house/shed/etc. I don't anticipate that as the antenna will be totally obscured unless someone was up close and personal (next to my house) on my property. That would present a decidedly different problem for said person that relates to unlawful trespass and the 2nd amendment.
Unfortunately I can not get an antenna even 1/4 of a wavelength up. This is a 40m dipole which I intend to use on several bands with window line and a manual tuner. I have to work with what I have, which is the chimney. The trees I have are not satisfactory.
To everyone, would I be OK with 6 feet above the chimney w/o support, given a sturdy chimney?
Thanks,
Bill
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RE: Chimney mount for center inverted V support
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by WB5JEO on October 19, 2009
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I can't imagine that a chimney in good condition will have any trouble with that light load. Consider placing steel angle iron vertically along the corners of the brickwork to spread the load of the straps, using at least two straps (or stainless steel cables).
By the way, although this fairly discrete antenna shouldn't attract the ire of most HOA's, you get no break from the Constitution on them poking around to get a look at it. They're not a government and therefore aren't bound by it.
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RE: Chimney mount for center inverted V support
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by N4UM on October 19, 2009
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I just moved into an HOA neighborhood. I have a 40 meter dipole in my attic 17 feet above ground. It is fed with high quality ladder line. Although it is in close proximity to wiring and aluminum A/C ductwork, it works fairly well.
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RE: Chimney mount for center inverted V support
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by VE3ENG on October 19, 2009
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Interesting ...
I once had double bazooka mounted to a 1"X2"X10' piece of wood strapped around a chimney with nylon rope. Yes, i know, kind of cheap and flimsy; but the installation was "temporary".
The bazooka was inverted and less than 180 degrees. So if you look downwards from the sky, it was shaped like a "V". This was a problem, eventually the weight of the antenna cause the wood to bend like a banana.
After 13 months i eventually moved, took down my antenna and piece of wood. Antenna worked well and lasted through one winter ... end of story.
If i had to do it all over i would not use a piece of wood or nylon rope to support it ... ;-)
Hope this helps.
73, James
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RE: Chimney mount for center inverted V support
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by N5LRZ on October 20, 2009
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Re Comming....
The legal point centers NOT NOT NOT on weither the antenna is visible or NOT. It centers on wheither it is "EXTARNAL" and what the LEGAL procedures that you signed off on of your own free will.
In short you could have very well legally signed away any and all rights to any kind of an external antenna and possibly any chance of any kind of an amateur radio hobby as long as you live there.
But you, yourself are NOT qualified to determine this. You need someone versed in Contractual LAW aka your own bar certified attorney.
IF IF IF your attorney says you legally have to get the permission of a HOA Committee to put up an antnenna (along with permits requred by any county or city agency of course) then do it legal because IF there is a fine or penalty for breach of contract the HOA or another home owner just damn well might drag your azz to court on a legal action for breach of your contract with any resultant HOA fines PLUS the cost of your attorney and any legal and file fees as well.
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