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## [TowerTalk] Long Masts -- Intermediate Bearing?

 To: [TowerTalk] Long Masts -- Intermediate Bearing? k4oj@ij.net (Jim White, K4OJ) Fri, 3 Apr 1998 08:02:12 -0500
 ```One of the neat things about rotors and beams brought to light by K0PP was that if you are using a typical rotatator it turns at about 1 RPM. Because things are moving slowly the same kind of tolerances normally sought for something like a car axle or drill press motor are not needed. If you are a little out of whack it is no biggee....it is not spinning like crazy so you should be fine whit "amateur" standards. On the second shelf (the intermediate one) we use a sheet of aluminum from the scrap yard cut to size and the use geometry to find its center. After making a triangle whose sides are equal in length, take the length of the side and "cut it in half", at this midpoint use your square to construct a right angle. Repeat this for all three sides....the intersection of the three right angles in the center of the plate is just that....where your hole should be. This was a proof from geometry class...something along the lines of the bisectors of the sides of an equilateral triangle will intersect at the center....whatever....cannot believe I remember stuff like that from a quarter of a century ago - guess what Mom and Dad said was true...you will not use everything you are taught in school, but some of it you do! While at the scrap yard pick up a piece of angle stock to bolt onto the corners, and to also provide a location for your u-bolts which will attach to the tower legs. Another trick I like is to make the plate a little bigger than it should be and then notch out for the diagonal braces. If you did this you can then put the plate such that it sits on the horizontal part of the tower's cross braces and the vertical forces that bearing may have to carry when you do a change out of the rotor are passed to the welded rung....not the ubolts, the u-bolts now just have to keep things centered. By now you are asking why those angles in the corner don't prevent the plate from dropping so close to the horizontal....another trick....mount the angles on the top side of the plate, so they "stick up"> This has worked very well for us at the W1CW/W1YL station. I feel very comfortable with the end result. The latest frill we have added but I haven't had to use yet is on the top plate of the latest top section installed there are several small holes in it. These holes match the base of an automobile jack I bought at a flea market. When it is time to boost the mast to do a rotor changeout next time I will be able to bolt the car jack to the top plate - align the boom over it and the mast will go vertical as I raise the jack....it is ready to boost - no slings/clamps/comealongs will be needed. Now is a good time to do this stuff...before you go vertical, and wish you had done it! Less than a month til the Florida QSO Party! 73, see you in the FQP Jim, K4OJ Florida Contest Group - visit our website at: http://www.4w.com/deemer/fcg.htm What's an FQP? The Florida Contest Group is pleased to announce the rebirth of the Florida QSO Party, check out the FQP website@: http://home1.gte.net/wd4ahz/fcg/ssqp.htm -- FAQ on WWW: http://www.contesting.com/towertalkfaq.html Submissions: towertalk@contesting.com Administrative requests: towertalk-REQUEST@contesting.com Problems: owner-towertalk@contesting.com Search: http://www.contesting.com/km9p/search ```
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