Google says 1.5" EMT is actually 1.75" OD and .065" wall thickness and
yield strength is 35,000 psi.
Putting these numbers in a mast analysis program and using a 7 sq ft wind
load 24" above top of tower, failure happens at a wind speed of 84 mph.
Lowering to 12" above tower top, failure is at 119 mph.
So, it could be useful in a modest installation.
73,
Gerald K5GW
In a message dated 3/15/2016 2:01:59 P.M. Central Daylight Time,
infomet@embarqmail.com writes:
Let’s not call names.
An EMT mast is great, as long as you don’t get greedy and make it too tall
outside the tower.
Mine is about 2’ above the tower top and I think it will survive any wind
likely in my area. And I really won’t cry if the $150 beam is damaged!
It’s several years old and shows no sign of deterioration. It cost almost
nothing and weighs next to nothing.
So I have a used tower, used tribander, used rotator, EMT mast, but new
coax.
I also have a HB amp made from used components, with an easy KW+ output.
It’s a rare pileup I can’t get through.
I am VERY happy, but may change to an LPDA so I can get the WARC bands,
someday.
I also use junk tubing from a kid’s swingset for Field Day. It’s worked
fine for a decade or so.
Successful systems can be designed around most any components, as long as
one doesn’t try to do too much!
I’d far rather see a ham put up 30-40 feet of used tower and a used
tribander than envy those with more elaborate, expensive setups!
A few more hours on the air will make up for a few dB of antenna
performance and there will be money left for beer.
Wilson
W4BOH
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