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Old 05-28-2009, 05:00 PM   #16
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EMT as antenna mast?


I went to HD today and priced out the EMT. I found that if I use 1-1/4", I have to buy the ground clamp for 1-1/4 to 2" and it is much more expensive than the one for 1/2" to 1" tube, so I think I'm going to use 1" EMT.

I was surprised at how heavy EMT is. The wall is a lot thicker than I had expected, so 1" will be fine.
BTW, the difference in cost of the clamps is about $2 for the 1/2" to 1", and nearly $7 for the 1-1/4" to 2". The two clamps aren't really comparable though, as the larger one was brass, or maybe bronze, and the smaller one was nickel plated steel.

I'm going to check out an electrical supply house before I buy anything from HD.

FW

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Old 05-28-2009, 06:49 PM   #17
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EMT as antenna mast?


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I'm going to check out an electrical supply house before I buy anything from HD.
Good call.
Stick with a bronze clamp, even the small one.
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Old 05-28-2009, 09:36 PM   #18
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EMT as antenna mast?


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Good call.
Stick with a bronze clamp, even the small one.
Thanks for the advice. I guess the plated ones just rust out in a few years.
Considering the cost and labor involved with this project, I shouldn't cheap out on one of the more important parts.

FW
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Old 05-29-2009, 12:00 AM   #19
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EMT as antenna mast?


I once used a 10' stick of 1/2 EMT horizontally atop a light pole to suspend some plastic flags. Lasted 2 days 'til it bent.


Simple flags like these.



http://tbn0.google.com/images?q=tbn:...MultiColor.gif


The wind has a lot of force.

3/4 " Black pipe will do the trick.
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Old 05-29-2009, 06:54 AM   #20
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EMT as antenna mast?


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I once used a 10' stick of 1/2 EMT horizontally atop a light pole to suspend some plastic flags. Lasted 2 days 'til it bent.
.....

3/4 " Black pipe will do the trick.
There is a HUGE difference between 1/2" EMT and 1" EMT with regard to strength.

Also, 1" EMT is very close to the diameter of a specific antenna mast and even stronger.
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Old 05-29-2009, 07:47 AM   #21
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EMT as antenna mast?


I am going to go with 1-1/4" EMT. That's the standard size for antenna mast.
The only reason I thought of using 1" was that the ground clamp for 1" pipe was a lot cheaper than the one for 1-1/4", but I later realized that I was not looking at the same type of ground clamp. I need to use the bronze one, so the difference in cost isn't so much.

Judging by the thickness of the wall of 1-1/4" EMT, it is heavier than the steel mast pipe I used to buy from Radio Shack. Even those never bent, and I had some pretty heavy antenna on them, including a Wilson rotor (large one for amateur radio Yagi).

This antenna has a low wind loading. It's only a vertical 14ft high, with three small (20") radials at the bottom.

FW
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Old 05-29-2009, 09:25 PM   #22
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EMT as antenna mast?


I used an 1-1/4 inside a 1-1/2" emt to hold my Davis wireless weather station. This was about 15' above our rear deck. I never had a problem until a tornado came through and the mast bent - when the wind hit 190 MPH !
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Old 05-30-2009, 09:09 AM   #23
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I used an 1-1/4 inside a 1-1/2" emt to hold my Davis wireless weather station. This was about 15' above our rear deck. I never had a problem until a tornado came through and the mast bent - when the wind hit 190 MPH !
The instrument actually remained operational up to 190mph?

FW
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Old 05-30-2009, 11:46 AM   #24
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EMT as antenna mast?


I didn't realize it for some time. The only thing usable after the tornado was the console so I bought a completely new system. When I eventually downloaded the old console to my laptop it had recorded 190 MPH winds. I actually suspect it may have recorded higher winds if the mast hadn't bent allowing the station to hit the roof (before the roof left).


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The instrument actually remained operational up to 190mph?

FW

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