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Re: [TowerTalk] Aluminum Masts

 To: Re: [TowerTalk] Aluminum Masts Robert Chudek - KØRC Robert Chudek - KØRC Sun, 20 Aug 2006 12:24:03 -0500
 ```Allen, We just had a discussion regarding masts on the Minnesota Wireless Assn reflector. You can use this on-line mast calculator to determine whether an aluminum or steel mast is needed for your specific situation: It's provided by WD9P and you will find it here: http://www.math.niu.edu/KARC/mast In general, if you're not stacking large yagi's, and you don't live in a hurricane zone, aluminum can meet the task. But it's best to do a "worse case scenario" for your situation and then decide which way to go. BTW, the 35,000 psi figure in the calculator for aluminum is conservative, 6061-T6 is about 42,000 psi (a pretty common alloy) and the 7075 alloy (if you can find it) is over 70,000 psi. Chrome-molly steel is generally 110,000 psi. It's best to ask the supplier for the exact specifications of their material but you can do a Google search to get a "feel" for reasonable figures to use in your calculations. The calculator is *fun* to do some "what if" scenarios... What if I pushed that TH-11DXX (12.5 ft^2) antenna up from 1 foot to 15 feet above the top of the tower? 73 de Bob - K0RC in MN > Message: 1 > Date: Sun, 20 Aug 2006 04:13:15 -0700 > From: "Bill" > Subject: Re: [TowerTalk] Aluminum Masts > To: "JC Smith" , , > "'Tower Talk Reflector'" > Message-ID: <031d01c6c449\$a2a84030\$6601a8c0@attorneyg97r4a> > Content-Type: text/plain; format=flowed; charset="iso-8859-1"; > reply-type=original > > Allen > There are two primary issues to consider between steel and aluminum. They > are torsional rigidity and yield strength. Since aluminum has about 1/3 > the > Young's modulus of steel it will require a thicker tubing for the same > outer > dimension to obtain ths same torsional rigidity. Aluminum is also > generally > much lower in yield strength than steel too (although there are weak > steels > and storng aluminums) so the amount of torque that will induce a > permanent > set in the mast will also depend on the cross section being used as well > as > the yield strength. Each of those questions would need to be answered in > order to make a comparative determination. I have used both successfully > but each situation needs to be considered individually. > > 73 > Bill > W7VP > > > ----- Original Message ----- > From: "JC Smith" > To: "'JC Smith'" ; ; "'Tower > Talk Reflector'" > Sent: Saturday, August 19, 2006 8:09 PM > Subject: Re: [TowerTalk] Aluminum Masts > > >> Sorry, that was a bit blunt. What I meant was you need to calculate your >> load and see what kind of mast will handle it. Obviously, "regular" >> aluminum (like 6061-T6) won't handle the load steel will, size for size. >> OTOH, if you really need aluminum for some reason, there are some really >> strong alloys that will (at a price) match, and even outperform, some >> steels. I bought a military surplus, telescoping aluminum mast at a >> swapmeet many years ago. Have no idea what the alloy is, but it's one >> heavy-duty chunk of metal. >> >> Steve, K7LXC, who sponsors this reflector, has a nice little program >> called >> MARC (Mast Antenna Rotator Calculator) that will help you figure out what >> you need. You might check it out at: >> http://www.championradio.com/misc.html >> >> 73 - JC, K0HPS >> >> >> -----Original Message----- >> From: towertalk-bounces@contesting.com >> [mailto:towertalk-bounces@contesting.com]On Behalf Of JC Smith >> Sent: Saturday, August 19, 2006 7:52 PM >> To: britech@earthlink.net; 'Tower Talk Reflector' >> Subject: Re: [TowerTalk] Aluminum Masts >> >> "Expert" opinion: do the math. >> Link to aluminum masts: http://www.texastowers.com/aluminum.htm >> >> 73 - JC, K0HPS >> >> -----Original Message----- >> From: towertalk-bounces@contesting.com >> [mailto:towertalk-bounces@contesting.com]On Behalf Of Allen R. Brier >> Sent: Saturday, August 19, 2006 6:36 PM >> To: 'Tower Talk Reflector' >> Subject: [TowerTalk] Aluminum Masts >> >> Sometime recently, someone provided a source for aluminum masts. I would >> like to get that information again, please. >> >> Also, what "expert" opinions can I get from the group on using aluminum >> masts vs. steel? >> >> 73, >> >> Allen Ross Brier, N5XZ _______________________________________________ _______________________________________________ TowerTalk mailing list TowerTalk@contesting.com http://lists.contesting.com/mailman/listinfo/towertalk ```
 Current Thread [TowerTalk] Aluminum Masts, Allen R. Brier Re: [TowerTalk] Aluminum Masts, JC Smith Re: [TowerTalk] Aluminum Masts, JC Smith Re: [TowerTalk] Aluminum Masts, Bill Re: [TowerTalk] Aluminum Masts, David Thompson Re: [TowerTalk] Aluminum Masts, W3YY Re: [TowerTalk] Aluminum Masts, Robert Chudek - KØRC <= [TowerTalk] Online Mast Calculator, David Hachadorian