[TowerTalk] tower talk

[Donald Hofmann]

Thanks for the input. To answer some of your questions. The windload of the antennas (HF beam & 2M/440 beam), rotor and mast should be 8 sq. ft. I will use a 87,000 psi steel mast 10' long with 6' above the top of the tower. Standing on the top and tying on to the mast to install the 2M/440 beam shouldn't be a safety hazard (as far as the mast bending). Concerning guy wire spacing, from what I have read 60-80% is ok. Mine would be right at 70%. The ARRL Antenna book recommends the guys at the top of the tower instead of 5' down as Rohn says. The shifting soil problem is not fixable. Houses in this area crack and shift. A new house next to me has concrete piers 20' deep and their house still moves. We have clay which in the summer drys and shrinks and when wet, swells and expands.  Any more help is appreciated.> To: electroubleshooter at hotmail.com> Date: Fri, 12 Dec 2008 12:42:32 -0500> Subject: tower talk> From: k4za at juno.com> > hi Don:> > Well...since the tower has shifted over time, perhaps you should consider> having a soil analysis done--your county extension agent can probably> help you.> > Since it has shifted, climbing it w/o even temporary guys (use steel!!)> is probably not the smartest idea in the world. Don't do it!> > Since you do not say what antenna (load) you intend putting up there,> it's difficult to comment on your decision to use a flat top & bearing,> et cetera. The flat top is a good idea if you indeed use a thrust> bearing.> Having the guys right at the very top of the tower isn't such a swell> idea, however, as it makes tramming loads up more problematic....most> modern rotators are designed to hold/carry the load w/o trouble.> > Nor is standing up there (depending upon what you choose/use for mast> material) perhaps such an easy solution, either! > > Hams often stick lonnnnnngggg masts in their tower & affix lots of> antennas to them, when simply making the tower taller is a wiser choice,> hi...> > Regarding guys: I would suggest taller guy posts--or further in the> ground than 3 ft w/4 ft out. Depending on the post material, I'd> certainly make certain I belled out the bottoms of those holes,> especially considering the tower has already shifted! Indeed, I not use> a round post, but an I-beam or channel instead--to help prevent such> shifting. If you do use posts, consider putting some rebar inside along> w/concrete. Rohn specs call for 22-ft & 45-ft spacing on the tower, out> 80%. Since you're limited to closer spacing, using the elevated posts is> a good idea. I'd stick w/that recommendation. > > Regarding catenary: I'd use SS aircraft cable instead of EHS for the> catenary line. It's way more flexible (which is a good thing for this> application) & lighter & readily available. Cable ties should work fine> (use UV ones). You do not need to worry about the flexing vis-a-vis your> coax in my opinion. No need to tie things to it loosely--that'll create> more problems than it solves. Make the bundle as tight & small as> possible.> Anything from 213 to the LMRs will be fine. Again, w/o knowing the> frequencies in questions, it's impossible to comment on loss factors. > > Welcome to the hobby; it's the best there is!> > GL & vy 73 Don K4ZA> > Tower Works> Charlotte NC> > ____________________________________________________________> Save $15 on Flowers and Gifts from FTD!> Shop now at http://offers.juno.com/TGL1141/?u=http://www.ftd.com/17007
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