[TowerTalk] MASTS

[TexasRF at aol.com]

Hi Ryan, that was the raw data, no safety factor added. The wind speed  
given is actual steady wind speed, no average or gust and failure is defined as 
 the point the yield strength has been exceeded. 
 
Gerald
 
 
 
 
 
 
In a message dated 3/15/2016 3:12:18 P.M. Central Daylight Time,  
ryan.turner at memhamwan.org writes:

Gerald,  


Thanks for providing the numbers. Wind speed here is what -- average or  
instantaneous? How is failure defined? Curious to determine MTBF.


On Tue, Mar 15, 2016 at 2:35 PM, TexasRF--- via  TowerTalk 
<_towertalk at contesting.com_ (mailto:towertalk at contesting.com) > wrote:

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_ (mailto: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
_______________________________________________



_______________________________________________
TowerTalk   mailing  list
_TowerTalk at contesting.com_ (mailto:TowerTalk at contesting.com) 
http://lists.contesting.com/mailman/listinfo/towertalk

_______________________________________________



_______________________________________________
TowerTalk  mailing list
_TowerTalk at contesting.com_ (mailto:TowerTalk at contesting.com) 
http://lists.contesting.com/mailman/listinfo/towertalk








-- 

Ryan Turner, K0RET
+1.901.300.0039

_HamWAN Memphis Metro_ (http://www.memhamwan.org/)  - Memphis' Amateur 
Radio  Multi-Megabit IP  Network