[TowerTalk] MASTS

[Ryan Turner, K0RET]

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> 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 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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-- 
Ryan Turner, K0RET
+1.901.300.0039

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