----- Original Message -----
From: "K8RI on Tower talk" <firstname.lastname@example.org>
Sent: Friday, January 20, 2006 11:35 PM
Subject: Re: [TowerTalk] Rotator at bottom of tower
>> Given that the mast would have to be large, I would use schedule 40
>> pipe about 4 inches in OD but will probably not do it unless I run into a
>> scrap deal on the pipe. Regarding the welding process, I am sure that a
>> plate, perhaps about 3/8" thick, 6 inches wide and 2 foot long at each
>> with a few heavy duty muffler clamps would hold it. You could even pin
>> for extra insurance. Painting a perfectly straight line on the entire
>> length of the pipe would give visual confirmation as to whether it had
> I have the rotator mounted down in the tower. There is about 44 feet (two
> standard lengths) of 1 1/2 structural steel tubing with 1/2" wall. The
Whoa! I can't trust this keyboard. That's supposed to be 1/4" wall
> center of this is reinforced with 22' of 2" steel tubing with a 1/4" wall
> which leaves about 10 to 11 feet of 1 1/2" above and below the 2". The 2"
> is now pinned in 4 places. With 2 5/16" bolts one sheared off so it now
> two 3/8 bolts on each side of center. Even with all the stuff I have up
> there I get very little rotational movement.
>> 3.5 inch schedule 40 aluminum pipe would be 63 pounds per 20 foot length.
>> If I had a large enough hold in the top of the tower, I don't think I
>> have a problem dropping them through the top.
> If you have a top plate you would have enough room to weld flanges on the
> pipe and lower those down through the top. It takes one whale of a good
> pole to hole 20' of pipe though. They generally come in an odd length of
> or 22 feet. Aluminum may come in standard 20' lengths.
> Roger Halstead (K8RI and ARRL 40 year Life Member)
> N833R - World's oldest Debonair CD-2
>> Mounting the rotator independent of the tower would take the torque off
>> tower and if a thrust bearing could also be independent of the tower
>> would be no weight on the tower itself from the mast and antenna.
>> Sounds like a lot of work and perhaps I will not do it but still
>> the possibility.
>> Stan, K5GO
>> ----- Original Message -----
>> From: "Wolfert, William R." <WWolfert@columbuspolice.org>
>> To: <email@example.com>
>> Sent: Friday, January 20, 2006 7:40 AM
>> Subject: RE: [TowerTalk] Rotator at bottom of tower
>>> I'm not an engineer but I agree with the other TT'ers that indicate the
>>> pipe is too flimsy to handle the torque to which it will be exposed. You
>>> didn't say what type of tower you have, but did you consider how you
>>> get long sections of pipe into the center of the tower, unless you plan
>>> use a crane. I have AB-105 tower, which bolts together and I had
>>> inserting a piece of 3" about 21' long to use as a drive pipe (from a
>>> pitch) to turn 3 separate antennas on side mounts. I pictured unbolting
>>> enough side braces to slip the pipe inside. OK that would work. THEN...
>>> pictured myself on the tower trying to get the pipe into the hole I made
>>> do all my antenna/tower work by myself- as do many TT'ers I've come to
>>> learn- great encouragement!) and realized this would be a mechanically
>>> difficult venture. And that's with tower that I could make a much larger
>>> "hole" in by unbolting the braces. Even if you have help, really picture
>>> doing the task, maneuvering a (very) heavy piece of pipe from one end
>>> putting it into a very small space with lots of little hands to grab it
>>> (tower bracing). And that is just one piece. You mentioned you need
>>> Once the pieces are inside the tower, they then need to be connected
>>> (welded) together! I think this is not a small task at all. Good luck
>>> whatever you decide and if you go for it, be safe my friend.
>>> 73's Bill WR8K
>>> -----Original Message-----
>>> From: Stan Stockton [mailto:firstname.lastname@example.org]
>>> Sent: Wednesday, January 18, 2006 7:55 PM
>>> To: email@example.com
>>> Subject: [TowerTalk] Rotator at bottom of tower
>>> I am "considering" the possibility of running 105 feet of pipe extending
>>> existing mast to near ground level and mounting the rotator at that
>>> location. The antenna is 20M5L48. I have to take the rotator down
>>> of a maintenance issue anyway and thought that in the long run it might
>>> nice to have the rotator low to the ground.
>>> The plan would be to use 1.5" Schedule 40 pipe (1.90" OD), leave the two
>>> thrust bearings that are located at the top of the tower and down about
>>> foot, add another thrust bearing about 10 feet above the rotator and
>>> about 3 or 4 other brackets with UV inhibited PVC bearings to center the
>>> mast from about 20 feet to about 110 feet.
>>> If any of you have done something similar, I would appreciate knowing
>>> pros and cons of such a plan.
>>> Thanks...Stan, K5GO
>>> TowerTalk mailing list
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