Hello TTer's: I have a question on the smallest part of my tower. Now, be advised, this is my first tower in over 25 years and this may seem a trivial question. My tower, a UST HDX-572, came with a s
Richard: OK, now I understand why it seemed to screw on and then stop. I thought initially that it was stuck - but I can see now that was normal. I pumped several times with the grease gun on the mai
Do I understand correctly....that the thrust bearing (a) takes the weight off the rotor, and (b) allows removal of the rotor while leaving the mast and antennas in place? Any other purpose(s)? I have
Do I understand correctly....that the thrust bearing (a) takes the weight off the rotor, Not at my QTH, I personally do not but many hams DO use it in this manor. A typical ham rotor can more than ha
Jerry Keller wrote: Do I understand correctly....that the thrust bearing (a) takes the weight off the rotor, Not Really and (b) allows removal of the rotor while leaving the mast and antennas in plac
My thrust bearing has only two setscrews... at 90 deg to each other. That's what led me to think that the thrust bearing is a weight-carrying device, to take vertical load off the rotator. Many have
One of most common thrust bearings is the Rohn TB-3 http://www.texastowers.com/rohntb.htm You can see that it has three "set" screws. Without three (or four) the mast would, by definition, not be cen
What is wrong with using a bearing at the top of the tower and mounting the rotator inside the tower? The rotator has an internal bearing so the mast is supported by two points. I have built all of m
Author: Jon Pearl - W4ABC <jonpearl@tampabay.rr.com>
Date: Thu, 07 Feb 2013 09:07:20 -0500
Hi John. There's nothing wrong with the combination you cite. At present, my rotator *is* inside the tower where it's been for more than twenty years but with no thrust bearing at the top of the towe
John, I don't think USTower anticipates 16 feet of mast sticking out the top of the tower. If you have much in the way of antennas attached to that mast, it may to exceed sideload potential foreseen
2 points with the first beingm John is correct, a 16' mast putting the antenna 16' above the top of the tower substantially derates the tower below the 18 sq ft original rating. The other is, you alr
Author: Jon Pearl - W4ABC <jonpearl@tampabay.rr.com>
Date: Thu, 07 Feb 2013 12:10:05 -0500
Hi Roger and Mike. 2 points with the first beingm John is correct, a 16' mast putting the antenna 16' above the top of the tower substantially derates the tower below the 18 sq ft original rating. I'
A simple minded, approximate approach to this would be to look at it as a bending moment problem. Making an assumption that the manufacturer's 18 sq ft allowed load is 4 ft above the sleeve, which is
Sorry for the way that got formatted. I'll try for a narrower format for the table.- item sq ft lbs/sq ft ft to fulcrum moment -- -- -- -- -- mast(2"cyl surface) 2 x 6 12x HF tribander 8 x 1 8x 6 met
Correction to my previous re mast loading. I think my mind was on vacation. Clearly, 18 x 4 = 72, not 64. Therefore in the example shown there is room for another 8x worth of antenna. e.g. 1 more sq
Author: Jon Pearl - W4ABC <jonpearl@tampabay.rr.com>
Date: Thu, 07 Feb 2013 22:56:44 -0500
Hi Gene. I see you're not too far from Jeff, W2FU. I'll be turning the new OR2800 with one of his controllers. I'm pretty excited about that! Thanks for taking the time to do the initial work-up for
It been a while since my mechanics course, but I think the accurate way to calculate the loads is to translate the individual antenna wind loads to moments at the tower base. Then sum these and see i
Hi Grant - It's been a few decades since I took my ME courses also. There are obviously many refinements to my suggested quick look, such as conditions on the mfg's spec's, guying, column loading, ma
When it come to towers I am still very much in a learning process. I have never owned a tower and I joined this group to learn everything I can so that some day I could get one installed. Please keep