[TowerTalk] MASTS

[TexasRF at aol.com]

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 at 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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