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## Re: [TowerTalk] FW: Sources for mast material

 To: towertalk@contesting.com, k5mef@mefox.org Re: [TowerTalk] FW: Sources for mast material K7LXC@aol.com Thu, 7 Aug 2008 13:02:40 EDT mailto:towertalk@contesting.com>
 ``` In a message dated 8/7/2008 9:02:46 A.M. Pacific Daylight Time, towertalk-request@contesting.com 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 says "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 there. The over-riding spec is your county windspeed rating from the TIA-222 windspeed chart (available from _http://www.championradio.com/windspeed.php_ (http://www.championradio.com/windspeed.php) ). There are several ways of arriving at a figure. > 2) Also, when the calculated total is 12,290 in-lb, the lightest suggested 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. Cheers, Steve K7LXC _www.championradio.com_ (http://www.championradio.com) and TOWER TECH **************Looking for a car that's sporty, fun and fits in your budget? Read reviews on AOL Autos. (http://autos.aol.com/cars-BMW-128-2008/expert-review?ncid=aolaut00050000000017 ) _______________________________________________ _______________________________________________ TowerTalk mailing list TowerTalk@contesting.com http://lists.contesting.com/mailman/listinfo/towertalk ```
 Current Thread [TowerTalk] FW: Sources for mast material, Michael Fox \(K5MEF\) Re: [TowerTalk] FW: Sources for mast material, K7LXC <= [TowerTalk] Antenna Interaction, Edward Sylvester Re: [TowerTalk] FW: Sources for mast material, Michael Fox \(K5MEF\)