As a feasibility check, here is a potential design: I'd like at least a 2 x tribander stack (10 sq ft ea, e.g. TH7DX or SteppIR DB-18) and a 2 el 40m beam (various) on a crank up/tilt over tower, hei
Bosch and DeWalt make a driver bit specifically for ground rods, check with a contractor or electrical supply dealer. I bought one from ToolUp in Santa Clara, CA. Online at http://www.toolup.com/sear
Steve, Several alternatives as these are about 1+ tons. For smooth boulders the following have worked for me; If you can get a tractor/dozer nearby with a winch it is easiest to skid them along with
A full synthetic grease, particularly loaded with Teflon should work well, at least for my rebuilds I'm happy. My favorite is Super-Lube from Synco Chemical, available many places including MSC, McMa
I use a low stretch braided dacron that is made by New England ropes in a 7/16" size, which I find is the smallest line that has good hand, can be tied easily, and fits the rohn gin pole fittings. We
"near the house" How near? I reinforced the gable studs on one house to be strong enough for a block and tackle. It lifted 30' of Rohn 25 plus 15' of mast extension with a TH7DX to a house bracket mo
For some 425 Mhz high power amateur rocket telemetry (APRS packets) I've built a MOXON turnstile (Cebik, QST August 2001) from brass brazing rod 0.093" dia. Now the challenge is to try and measure wh
My suggestion was the rope over the roof as a sky hook, for a block and tackle rig that did the lifting. Otherwise, there will be damage to the rope, the roof, and a bad situation with a lifting crew
Agreed that constructive help is best. Here is a quick sanity check on the danger actually involved with the rigging as photographed. I've taken down worse (after some temporary guying). EHS and Phil
Jim, Quite a horror story. It seems you did a lot of smart things with the installation, but they weren't enough. I'm no lightning expert but here are some thoughts: An earlier post (which I can't fi
My top loaded 80m vertical on my galvanized barn roof is made from 2 x 20' 3" irrigation pipe with a 12' diameter capacity hat. Here are some suggestions: You need the side guys at all times when you
I had an 80m dipole that used 7/8" od bare aluminum CATV hardline. It had a real nice bandwidth (at least 2x 14 ga wire) and the copperweld center conductor is strong. To connect to the shield at the
A "trucker's hitch" is a lot cheaper, probably more secure, and likely stronger as the rope isn't point compressed. There are lots of versions to choose from, here are two I like Not a "real" trucker
6063 is cheaper than 6061 so is the alloy of choice for electrical conduit (sch 40) & irrigation pipe (sch 10 if it has gasketed couplers). Gas/water pipe uses NPT (national pipe thread) tapered thre
I'm a little confused by all the stress numbers being quoted. I think the number that matters is yield strength so the mast doesn't permanently bend. Tensile or ultimate has value only to insure it w
The torque tightening values for A325 or grade 5 galvanized bolts are sobering see http://www.portlandbolt.com/technicalinformation/bolt-torque-chart.html (note the cautions) some values that might b
You might consider Holobar thick wall aluminum tube, available from several sources on the web I usually find scrap ends at my local SIMS metal recycle yard or local Al remnant dealer. see http://met
For various reasons (some inherent in bearing manufacturing tolerances) three spaced bearings are almost never done in machinery - it's just too hard to get them/keep them aligned. Two bearings can h
Having the rotator take all the thrust load doesn't thrill me, but replacing a thrust bearing is a real pain. I guess I'm a convert to "no stock thrust bearings". However, my own design.... I just re
You are on the right track. The second rotator plate should have a plate with a hole just oversize for the mast. Then as the crane lowers the mast into the tower it will keep the mast near vertical.