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)
> >
> >
> >
> >
> > _______________________________________________
> >
> >
> >
> > _______________________________________________
> > TowerTalk mailing list
> > TowerTalk@contesting.com
> > http://lists.contesting.com/mailman/listinfo/towertalk
> >
>
>
> _______________________________________________
>
>
>
> _______________________________________________
> TowerTalk mailing list
> TowerTalk@contesting.com
> http://lists.contesting.com/mailman/listinfo/towertalk
>
_______________________________________________
_______________________________________________
TowerTalk mailing list
TowerTalk@contesting.com
http://lists.contesting.com/mailman/listinfo/towertalk
|