[Top] [All Lists]

Re: [TowerTalk] FW: Sources for mast material

Subject: Re: [TowerTalk] FW: Sources for mast material
Date: Thu, 7 Aug 2008 13:02:40 EDT
List-post: <">>
In a message dated 8/7/2008 9:02:46 A.M. Pacific Daylight Time, writes:

    Vis-a-vis the Champion Radio Products MARC  (Mast, Antenna and Rotator 
Calculator) Program:
>    1)  What is the meaning of the "wind speed"  parameter.  The dialog box 
"maximum wind speed expected".   In my county, basic wind speed is 70 mph
fastest mile, 85 mph 3-second  gust.  So I figured the max instantaneous is
probably higher.  So  I figured 90 or 100 would be a good number.  But it
really depends on  what the meaning of this number is in the MARC tool
(fastest mile, 3-second  gust, other).  Can you define?

We used the  formulas and specs from Dave Leeson's (W6NL, ex-W6QHS) book 
"Physical Design  of Yagi Antennas." Maybe there's more of an explanation 

The over-riding spec is your county windspeed  rating from the TIA-222 
windspeed chart (available from _ 
( ).  There are several ways of 
at a figure.  

>  2)  Also, when the calculated total is 12,290 in-lb,  the lightest 
mast type shown in the list is a 40,000 in-lb yield  strength.  It's seems
like it's only displaying mast types that are at  least 3X higher than the
calculated total.  Maybe you could shed some  light on that too?

No, that's because tubing has that as a  minimum rating. As opposed to pipe 
which doesn't; it's around 35 kpsi and  we don't include pipe as a generally 
suitable mast material.  

If your design yield strength is 13 kpsi, then  anything will work. That's 
why I suggested Schedule 40 or 80 water pipe or  conduit. You're over-thinking 
this whole thing. If you want to spend the  bigger bucks for a pedigreed piece 
of steel, knock yourself out. But IMO it  ain't necessary. 
Steve   K7LXC
_www.championradio.com_ ( 


**************Looking for a car that's sporty, fun and fits in your budget? 
Read reviews on AOL Autos.      

TowerTalk mailing list

<Prev in Thread] Current Thread [Next in Thread>