I use a similar solution to hold the bottom of the mast when changing out a
rotator. Three straight pieces of angle iron with u'bolts. Each piece
attaches to the mast with one u-bolt, and goes straight to a tower leg, with
another u-bolt securing it there. I have never been able to see any
movement of the bottom of the mast, but I still wait for a calm day just to
be on the safe side.
73, Tim - N3XX
----- Original Message -----
From: "Barry" <w2up3@verizon.net>
To: "Ron Todd" <ron@k4wz.com>
Cc: <towertalk@contesting.com>
Sent: Saturday, August 25, 2007 4:42 PM
Subject: Re: [TowerTalk] Fw: Rohn 45 Question
> Another option for mast stability when the rotor is removed is 2 pieces
> of angle iron, held together with a bolt and nut, shaped like the letter
> T. 2 U-bolts hold the top of the T to the tower face and 1 U-bolt
> through the mid-section of the vertical of the T holds the mast. Snug
> the bolts before removing the rotor, and everything stays put.
>
> Barry W2UP
>
> Ron Todd wrote:
>> So why does a rotator want to have that second thrust bearing?
>>
>> I wanted two because when you take the rotor out and with only one thrust
>> bearing you don't have control of the mast horizontally. With two TB you
>> always have control.
>>
>>
>>
>> ----- Original Message -----
>> From: "David Gilbert" <xdavid@cis-broadband.com>
>> To: "jeremy-ca" <km1h@jeremy.mv.com>
>> Cc: <towertalk@contesting.com>; <K7LXC@aol.com>
>> Sent: Saturday, August 25, 2007 3:03 PM
>> Subject: Re: [TowerTalk] Rohn 45 Question
>>
>>
>>
>>> Carl, you pretty much avoided Steve's question. What rotator failure
>>> mode is minimized by having two thrust bearings above the rotator? Can
>>> you give any examples of your YCCC buddies that would back up your
>>> comments? It would be interesting to hear their experiences first hand.
>>>
>>> I recently ordered a tower, rotator, and fairly large antenna system ...
>>> and both of the tower manufacturers I investigated strongly recommended
>>> against using two thrust bearings (at least if both were secured to the
>>> mast) for the same reasons Steve mentioned. A single thrust bearing at
>>> the top of the tower makes sense, but a simple plate inside the tower
>>> with a hole in it facilitates the task of replacing the rotator (which
>>> is a separate issue anyway).
>>>
>>> So why does a rotator want to have that second thrust bearing?
>>>
>>> Dave AB7E
>>>
>>>
>>>
>>> jeremy-ca wrote:
>>>
>>>> I take it then that you have never experienced the installation of a
>>>> large
>>>> stacked array without a crane.
>>>>
>>>> Old wives tales? Hmmm, most of those that I know have at least a
>>>> Masters
>>>> degrees in an engineering discipline.
>>>>
>>>> Plus NE Yankees are not known for spending money frivolously.
>>>>
>>>> Cheers Yourself
>>>> Carl
>>>> KM1H
>>>>
>>>>
>>>>
>>>>
>>>> ----- Original Message -----
>>>> From: <K7LXC@aol.com>
>>>> To: <km1h@jeremy.mv.com>; <towertalk@contesting.com>; <john@kk9a.com>
>>>> Sent: Saturday, August 25, 2007 1:21 PM
>>>> Subject: Re: [TowerTalk] Rohn 45 Question
>>>>
>>>>
>>>>
>>>>
>>>>> In a message dated 8/25/2007 10:00:45 A.M. Pacific Daylight Time,
>>>>> km1h@jeremy.mv.com writes:
>>>>>
>>>>>
>>>>>
>>>>>> Thats strange. Numerous YCCC and other serious contesters/DXers
>>>>>> with
>>>>>> big
>>>>>>
>>>>>>
>>>>> stacked arrays have been using dual bearings for decades with a
>>>>> significant
>>>>> reduction in rotator failures.
>>>>>
>>>>> Reduction because of what? Reduction from what to what?
>>>>>
>>>>> What actual mechanical improvement does the additional mid-bearing
>>>>> make?
>>>>> More torque reduction? No. More vertical weight reduction? No, the
>>>>> weight's
>>>>> already on the top bearing. A psychological improvement? Probably.
>>>>> More
>>>>> ham
>>>>> radio old wive's tales? Probably.
>>>>>
>>>>> Cheers,
>>>>> Steve K7LXC
>>>>> TOWER TECH -
>>>>> Professional tower services for hams
>>>>> Cell: 206-890-4188
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>
>>>>> ************************************** Get a sneak peek of the all-new
>>>>> AOL
>>>>> at
>>>>> http://discover.aol.com/memed/aolcom30tour
>>>>> _______________________________________________
>>>>>
>>>>>
>>>>>
>>>>> _______________________________________________
>>>>> TowerTalk mailing list
>>>>> TowerTalk@contesting.com
>>>>> http://lists.contesting.com/mailman/listinfo/towertalk
>>>>>
>>>>>
>>>>>
>>>> _______________________________________________
>>>>
>>>>
>>>>
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>>>>
>>>>
>>> _______________________________________________
>>>
>>>
>>>
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>>>
>>>
>>
>> _______________________________________________
>>
>>
>>
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>>
>>
>>
>
> --
>
> Barry Kutner, W2UP Newtown, PA
>
> _______________________________________________
>
>
>
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