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Radio Equipment Installation Forum Forum for discussing how to install radio communications equipment in Mobile, Base, Command Post, EOC, etc configurations.

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Old 01-17-2008, 5:46 PM
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Question Antenna Mast Height

I really appreciate all the help that has been provided. This weekend I will be installing a Ferret antenna using two of Radio Shacks's 4" side building mounts. The antenna itself weighs about 4lbs and appears as a single rod 8 ft in length and approximately 1 1/4" in diameter (looks like a grey broom handle). I had planned on using two 10 ft Channel masters steel masts which would give me a 20 ft mast. A friend advised that this mast would suffer too much torque in very high wind for the attachment points to the building and would eventually loosen. Another friend suggested that the antenna profile would create little wind resistance and the set-up would be okay. My objective is to get height.

Do you think that a 20 foot mast only supported by the wall brackets will be okay or do you think I should go with a 10 foot mast. The brackets will be about 2 1/2 feet apart and lag bolted through the exterior siding into the plywood sheathing. All but 3 or 4 feet will be above the roof peak and guide wires are not an option.

Thanks -

William
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Old 01-17-2008, 6:22 PM
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Since y guy wires are out. Without guy wires I wouldnt want more than 10ft of the mast above the roof line. To properly mount the mast to the house you need 5ft or more between house brackets so much of your lower mast will already be used up. The small whip antenna is going to below around but with only 10ft of mast you should be ok.

Last edited by n8emr; 01-18-2008 at 12:48 PM..
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Old 01-17-2008, 6:48 PM
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I would not rely on the sheathing.

Strongbacks will let you put the strain on the studs instead of the sheathing.

I go along with the five feet on the brackets and ten feet for the mast. With that set up, you will end up with about eleven feet of mast/antenna above the top support, which is one heck of a lever. Twenty one feet would be asking for trouble.
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Old 01-18-2008, 10:01 AM
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Personally I think the Radio Shack building mounts are too light duty, but then we get gusting Santa Ana winds where I live. Channel Masters make some excellent, heavy-duty building mounts and they yellow zinc-washed for corrosion resistance. (Come to think of it, I never had an R.S. mount rust, but the yellow zinc is a bit more "pro.")
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Old 01-18-2008, 12:52 PM
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There are several radio shack mounts, light duty and heavy, I would go with the heavy. Same with the mast, RS has some nice gray mask now that is pretty strong, Much better than the golden stuff they once had.

If you can get into the attic/crawspace then I would want to see the lag bolts go to a backerboard inside the house and not just into the sheathing.
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Old 01-18-2008, 3:42 PM
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Thanks for all the suggestions. I intend to use the backer board, The RS mounts that I have from RS appear heavy duty. My mast is a channel master heavy duty. I will only be using a 10 ft mast know. I think I am all set. Hope the weather is mild tomorrow.
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Old 01-18-2008, 5:01 PM
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Quote:
Originally Posted by Williamb
Thanks for all the suggestions. I intend to use the backer board, The RS mounts that I have from RS appear heavy duty. My mast is a channel master heavy duty. I will only be using a 10 ft mast know. I think I am all set. Hope the weather is mild tomorrow.
I too would only suggest the 10' height. If you were to use guy wires, I would suggest the 20 foot range. I have a Ringo out back on 15' of tube steel and that has held up ok. My main mast is 40' off the ground but I am using guy wires.

REMEMBER TO GROUND YOUR MAST!!! USE HEAVY GROUND WIRE AND AT LEAST AN EIGHT (8') FOOT GROUNDING ROD (available at most "full service" RS's.

73,
Gary
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Old 01-18-2008, 5:12 PM
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Thanks I have the mast grounding down but I also asked a question about coaxial grounding on another thread. That question really started a lot of posts. I am still thinking about how I will ground the coaxial.
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Old 01-18-2008, 5:22 PM
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Quote:
Originally Posted by Williamb
Thanks I have the mast grounding down but I also asked a question about coaxial grounding on another thread. That question really started a lot of posts. I am still thinking about how I will ground the coaxial.
You can get a coaxial lightning arrestor that has a grounding lug on it. You can pick them up at any Ham outlet (Lentini's has them in Newington). If your radio has a good ground, this will be a good ground also for RX.

Last edited by kb1awi; 01-18-2008 at 5:39 PM..
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Old 01-18-2008, 6:29 PM
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I bought all my equipment from Bill at Lentini's. I was discussing with him polyphasers (sp).

Thanks,
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Old 01-19-2008, 5:31 PM
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The guy's from Lentini's can help you out. You should go with more rugged brackets that the Radio Shack 4 inch mounts. Those wouldn't hold up well with New England weather. Good sturdy chimney mounts work, but you shouldn't use the ratchet type, because they loosen up.
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