Ok Dick, if it makes you feel better, I stand corrected.
---- Original Message -----
From: "RICHARD SOLOMON" <w1ksz@q.com>
To: "TowerTalk" <towertalk@contesting.com>
Sent: Wednesday, January 27, 2010 3:55 PM
Subject: Re: [TowerTalk] sched 80 mast
>
> I think that was W1FZJ and he said ..."if your antenna lasts through
> the winter, it wasn't big enough"... .
>
> 73, Dick, W1KSZ
>
>> From: w2lu@rochester.rr.com
>> To: towertalk@contesting.com
>> Date: Wed, 27 Jan 2010 10:44:46 -0500
>> Subject: Re: [TowerTalk] sched 80 mast
>>
>> How about repetitive gusts and possible resonance? But remember the Sam
>> Harris / W1FZ philosophy - "If it stays up more than two winters it was
>> over
>> designed".
>> ----- Original Message -----
>> From: "Jim Thomson" <Jim.thom@telus.net>
>> To: <towertalk@contesting.com>
>> Sent: Wednesday, January 27, 2010 10:09 AM
>> Subject: [TowerTalk] sched 80 mast
>>
>>
>> > VE9HF indicates his sched 80 mast is .25" thick. It's not.
>> >
>> > IF his mast is typ 1.9" OD sched 80 stuff... it's only .200" thick.
>> > His section modulus is only .412
>> >
>> > If the yield strength is 35 ksi.... his max bending moment is only
>> > .412 x 35 ksi = 14,420 in lbs...[ 1200 ft lbs]
>> >
>> > Lets say 7 sq feet @ 70 mph [20 lbs per sq ft] x 14' .... =
>> > 1960
>> > ft lbs of bending moment.
>> >
>> > 1960> 1200 ! The mast will snap like a tooth pick. The mast is
>> > maxed out with 1200/140 = 8.57'
>> >
>> > This doesn't even factor in the other TWO proposed yagi's... nor the
>> > wind load of the mast itself !
>> >
>> > It's NOT....." a serious tower" . It's made for TV ants'...
>> > and
>> > can be used with ham ant's,
>> >
>> > provided you don't overload it...esp with tall masts. Even if you
>> > guyed
>> > the tower, the proposed mast you
>> >
>> > are contemplating will fold over at a right angle. That Delhi
>> > isn't
>> > CSA approved, nor does it meet
>> >
>> > the Canadian S-37 tower specs. Load it up with heavy wet snow + a
>> > tiny
>> > bit of ice .....+ a 55 mph gust
>> >
>> > .. and it's bye-bye tower... plus 3 x ants' trashed. Removing a bent
>> > mast is a gong show in itself.. and
>> >
>> > extremely dangerous. If you want a stronger, self support tower,
>> > get
>> > a Trylon Titan..[with the 48" wide bottom section]...
>> >
>> > ... or better yet ..a Trylon Super Titan. The Trylon super Titan IS
>> > a
>> > S-37 rated tower, and will handle 25 mm of radial ice + high wind.
>> >
>> > It's the real deal. The stock Delhi top bearing plate + mating thrust
>> > bearing is pure junk. The rotor plate is worse. You will end up
>> >
>> > tearing up all the plates within months.
>> >
>> > Later.......... Jim VE7RF
>> >
>> > _______________________________________________
>> >
>> >
>> >
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>>
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