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Re: [TowerTalk] Sorry to bring up an oldie - Mast Material

To: K8RI on TT <k8ri-on-towertalk@tm.net>, towertalk@contesting.com
Subject: Re: [TowerTalk] Sorry to bring up an oldie - Mast Material
From: Rick Scott <w7psk@yahoo.com>
Date: Thu, 10 Mar 2011 07:24:40 -0800 (PST)
List-post: <towertalk@contesting.com">mailto:towertalk@contesting.com>
PS
Im planning on getting 7 or 8 ft of material.  4ft for inside the tower and 3 - 
4 ft above it.

I plan on mounting the Beam 2 - 3 Ft above the top.  I have a Mast Bearing in 
the
top of the tower also.




----- Original Message ----
> From: K8RI on TT <k8ri-on-towertalk@tm.net>
> To: towertalk@contesting.com
> Sent: Wed, March 9, 2011 10:29:12 PM
> Subject: Re: [TowerTalk] Sorry to bring up an oldie - Mast Material
> 
> On 3/9/2011 4:24 PM, K7LXC@aol.com wrote:
> >
> > In a  message dated 3/9/2011 12:01:25 P.M. Pacific Standard Time,
> > towertalk-request@contesting.com writes:
> 
> 
> As Steve says, the tripod mount is likely the weak point and  not the 
> current mast.
> I purchase 6061-T6 in 24' lengths with 1/8", 3/16"  and 1/4 wall. No, I 
> would not recommend a 24 footer be used in your  tripod.  I'm looking for 
> some stronger alloy and temper.
> 
> As for  your system I'd not go more than a few feet above the tripod, 
> unless the  roof is reinforced under the tripod and the tripod is bolted 
> to/through the  reinforcing and not just into the rafters.
> 
> Wind is strange as to what  survives and what fails.
> I used to install TV antennas as a sideline back in  the 60's and early 70's.
> At home I had a 5L 20 meter KLM on a 40' tower, a 6L  15 Meter KLM on a 
> 40' tower and a 7L 10 Meter Wilson (39' boom) on a 40'  tower. These were 
> relatively light steel towers on dirt bases and 3 way  guyed just below 
> the top of the tower.  Yes I needed larger towers but  that is what I had 
> at the time.
> 
> I installed a new, fairly large TV  antenna just above the top of a roof 
> mounted tripod. This tripod had two lag  bolts in each leg that ran 
> nearly through the respective rafter in pre  drilled holes so they 
> wouldn't split the rafters.  Just a day or two  after installing the TV 
> antenna (remember I did a lot of these) we had a  rather strong 
> thunderstorm. It literally split the rafters pulling the bolts  out and 
> took the tripod right off the roof, destroying the antenna in the 
> process. Yet the wind did no damage to any of the big antennas on the 
> 40' towers.
> 
> Just because a lightly built system survives a big storm,  does not mean 
> that system will normally, or can normally be expected to  survive 
> another storm of the same intensity. Nature is  fickle!
> 
> 73
> 
> Roger (K8RI)
> 
> >>   Im really  confused.  Id like to buy Local, because  the mail order
> >  houses have
> > Really high prices and high shipping
> > plus  they  only do 5 or 10ft intervals.
> >
> >>   I have a Glen Martin  9ft  roof mount tower.  Its just shy of 4ft from
> > the  rotor
> > to the top of  the tower.  Right now I have
> > a 2  1/2" Fence Post mast (really heavy  wall) that I hold an A4S up  with.
> >
> >>   A4 is going bad so I  decided to get my  dream antenna the standard
> > SteppIR 3
> > element beam and   nothing else will go on the mast.  I would
> > like to get 8ft as  that  will give me 4ft above the tower, I can put the
> >  antenna
> > at 2 - 3 feet and  be ok.
> >
> > Hiya, Scotty  --
> >
> >
> >      The 3L SteppIR isn't appreciably  bigger than the  A-4 you're currently
> > using. Go ahead and use what  you've got.
> >
> >      If you want to go a little  higher, use 1.5"  galvanized pipe (that's
> > the ID measurement - the  OD is 1.9"). The SteppIR  U-clamps are very snug 
>for
> > a 2" mast so  they'll work FB on a 1.9" piece of  steel.
> >
> >       The main factor is that it's going on a  roof-mounted tower. The  
tower
> > will likely blow off the roof before the mast  (whatever it  is) bends.
> >
> > Cheers,
> > Steve     K7LXC
> >  TOWER TECH
> > and
> > _www.championradio.com_ (http://www.championradio.com)
> >
> >
> >
> >
> >  _______________________________________________
> >
> >
> >
> >  _______________________________________________
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> > TowerTalk@contesting.com
> > http://lists.contesting.com/mailman/listinfo/towertalk
> >
> 
> 
> _______________________________________________
> 
> 
> 
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> 


      
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